Blood Biochemical Reference Intervals of Black Caimans (Melanosuchus niger) and Spectacled Caimans (Caiman crocodilus) in the Brazilian Amazon Region.

Reference intervals for physiologic parameters, crucial for assessing the health status of animals, have been documented for various crocodilian species across the globe. Nonetheless, the establishment of plasma biochemical reference intervals specific to Amazonian crocodilians remains incomplete. In an effort to address this gap, we procured blood samples from 65 black caimans (Melanosuchus niger) and 58 spectacled caimans (Caiman crocodilus) during the period of September-December 2019 within the Anavilhanas National Park in the Brazilian Amazon region We aimed to define reference intervals for 11 key plasma variables measured, namely glucose, triglycerides, total cholesterol, calcium, magnesium, sodium, potassium, albumin, total protein, uric acid, and urea. In general, the determined blood reference intervals aligned closely with those established for other crocodilian species. Some specific measurements, such as total cholesterol, sodium, and magnesium, exhibited distinct variations based on the species. Furthermore, female black caimans showcased elevated cholesterol levels compared with their male counterparts. Within the spectacled caimans, disparities related to sex were evident solely in the case of electrolytes sodium and potassium, with males demonstrating higher levels compared with females. These reference intervals not only provide data for assessing potential fluctuations in the health of wild or captive Amazonian crocodilians but also hold value for veterinary management.

Sources of intraspecific variation in the isotopic niche of a semi-aquatic predator in a human-modified landscape.

Intraspecific variation modulates patterns of resource use by species, potentially affecting the structure and stability of food webs. In human-modified landscapes, habitat disturbance modifies trophic interactions and intraspecific niche variation, impacting population persistence. Here, we investigated the relationship of sex, ontogeny, and habitat factors with the trophic niche of Caiman crocodilus in an agricultural landscape. We evaluated temporal variation in the trophic niche parameters using carbon and nitrogen stable isotope analysis from different body tissues. We found that caimans exploit the same carbon and nitrogen pools through time, with low isotopic variability between seasons, partly due to the slow isotope turnover rates of tissues in crocodilians. Conversely, the trophic niche of caimans varied across habitats, but with no evidence of a difference between natural and anthropogenic habitats. It apparently results from the influence of habitat suitability, connectivity, and caiman movements during the foraging. Our findings highlight the broader niches of juvenile caimans relative to adults, possibly in response of territorialism and opportunistic foraging strategy. Although using similar resources, females had a larger niche than males, probably associated with foraging strategies during nesting. Considering the sex and body size categories, caimans occupied distinct isotopic regions in some habitats, indicating apparent niche segregation. Ontogenetic trophic shifts in the isotopes (δ13C and δ15N) depended on sex, leading to resource partitioning that can potentially reduce intraspecific competition. Decision-makers and stakeholders should consider the trophic dynamics of sex and body size groups for the sustainable management and conservation of caiman populations, which implies in the maintenance of wetland habitats and landscape heterogeneity in the Formoso River floodplain.

Physiological stress response in free-living Amazonian caimans following experimental capture.

When captured, free-living crocodilians respond by hyperstimulation of the hypothalamic-pituitary-adrenal (HPA) axis, which triggers a cascade of downstream events of physiological stress. We examined these responses in two unstressed, and stressed Amazonian caimans, Caiman crocodilus and Melanosuchus niger. Plasma corticosterone levels increased in both stressed caiman species. In M. niger, the levels of this hormone increased 5.2-fold compared with the basal range values, while in C. crocodilus this was only 1.7-fold. After stress, M. niger needed more than 6 h to return its corticosterone levels to basal range values, whereas in C. crocodilus just 0.5 h was enough. Downstream events were characterized by an increase in glucose levels, which is associated with corticosterone increments. Excessive muscle activity resulted in increased plasma lactate content in both species. Lactate levels were also related to plasma calcium concentration, possibly due to the buffering capacity for preventing lactic acidosis. Clearance of excessive lactate load was faster in M. niger (0.5 h) than in C. crocodilus (more than 6 h). Although both caiman species respond in the same way to capture, the amplitude and duration of activation of the HPA axis are different. M. niger may be potentially more sensitive to acute stress than C. crocodilus. On the other hand, C. crocodilus needs more time to recover from the lactic acid load. Our experiment provides a useful diagnostic tool for management and conservation programs, as well as evaluating the impacts of tourism and recreational capture on caimans in the Amazon.

Early life differences in behavioral predispositions in two Alligatoridae species.

Behavioral predispositions are innate tendencies of animals to behave in a given way without the input of learning. They increase survival chances and, due to environmental and ecological challenges, may vary substantially even between closely related taxa. These differences are likely to be especially pronounced in long-lived species like crocodilians. This order is particularly relevant for comparative cognition due to its phylogenetic proximity to birds. Here we compared early life behavioral predispositions in two Alligatoridae species. We exposed American alligator and spectacled caiman hatchlings to three different novel situations: a novel object, a novel environment that was open and a novel environment with a shelter. This was then repeated a week later. During exposure to the novel environments, alligators moved around more and explored a larger range of the arena than the caimans. When exposed to the novel object, the alligators reduced the mean distance to the novel object in the second phase, while the caimans further increased it, indicating diametrically opposite ontogenetic development in behavioral predispositions. Although all crocodilian hatchlings face comparable challenges, e.g., high predation pressure, the effectiveness of parental protection might explain the observed pattern. American alligators are apex predators capable of protecting their offspring against most dangers, whereas adult spectacled caimans are frequently predated themselves. Their distancing behavior might be related to increased predator avoidance and also explain the success of invasive spectacled caimans in the natural habitats of other crocodilians.

Leucismo em jacaretinga: relato de caso / Leucism in jacaretinga: case report

Dentre os crocodilianos com ocorrência no Brasil, o Caiman crocodilus (Linnaeus, 1758) é a espécie de maior frequência, porém sua presença em estudos científicos restringe-se a levantamentos faunísticos, na maioria das vezes. O leucismo, também conhecido como albinismo parcial, é uma anomalia cromática ainda pouco conhecida. Indivíduos portadores dos genes que condicionam a doença apresentam ausência de pigmentação em uma parte ou em todo o corpo, porém os olhos não apresentam alteração. O objetivo deste trabalho foi realizar o primeiro registro de Caiman crocodilus com leucismo no mundo.(AU)

Among crocodilians in Brazil, Caiman crocodilus (Linnaeus, 1758) is the most frequent species, but its presence in scientific studies is mostly restricted to faunal surveys. Leukism, also known as partial albinism, is a still little known chromatic anomaly. Individuals with genes that condition the disease present no pigmentation in one part or in the whole body, but the eyes did not change. The objective of this work was to perform the first record of Caiman crocodilus with leucismo in the world.(AU)

Estado de la población del cocodrilo americano, Crocodylus acutus (Reptilia: Crocodilidae) y el caimán, Caiman crocodilus (Reptilia: Alligatoridae), en el Caribe central de Costa Rica

Dos especies de cocodrilianos han sido descritas en Costa Rica, el cocodrilo americano, Crocodylus acutus (Cuvier, 1807) y el caimán, Caiman crocodilus (Linnaeus, 1758). En Costa Rica se ha generado información de ambas especies, pero con énfasis en la vertiente del Pacífico, presumiblemente debido a su mayor desarrollo, lo cual ha acarreado mayor presión social hacia la atención de incidentes generados por el encuentro entre humanos y cocodrilos. El estudio se desarrolló durante el 2017 y en un área de aproximadamente 400 km2, caracterizada por tener una amplia densidad de cursos de agua que incluyen a los ríos: Matina, Pacuare, Reventazon y Parismina. En estos ríos se recorrió un promedio de 25 km desde la línea de costa hasta el interior del territorio, incluyendo los canales de Tortuguero, así como otros cuerpos de agua que conectan a estos ríos, lagunas importantes, y canales secundarios. Se realizaron tres repeticiones por segmento. Una población de 1 084 caimanes y 503 cocodrilos fue estimada, para una abundancia relativa de 8.64 y 2.80 ind/km respectivamente. Con respecto a caimanes poco más del 12 por ciento de los animales observados estaban en edad reproductiva, mientras que para cocodrilos sólo un 2 por ciento. La abundancia en los diferentes segmentos resultó ser significativamente diferente para ambas especies (Kruskal-Wallis, P 0.000). Mientras que la distribución por tallas de cocodrilos fue similar en todos los segmento (Kruskal-Wallis, P 0.15). Con 9 cocodrilos y 18 caimanes, reclutas o juveniles capturados, se calculó una proporción de sexos de 1.25 y 0.83 machos a hembras, para cocodrilos y caimanes respectivamente.

Two species of crocodilians have been described in Costa Rica, American crocodile, Crocodylus acutus (Cuvier, 1807), and caiman, Caiman crocodilus (Linnaeus 1758). In Costa Rica, data has been generated on both species, but populations in the Pacific have received more attention from researchers; presumably due to the fact that the Pacific slope has a greater development, which brings greater social pressure on the attention of the incidents generated by the encounter between humans and crocodiles. This study, performed during 2017, was done in an area of approximately 400 km2, characterized by having a wide and dense network of water courses, which includes the Matina, Pacuare, Reventazón and Parismina rivers. In these rivers, an average of 25 kilometers were traveled from the coastline up stream to the interior of the territory, including the Tortuguero canals, and other water bodies that connect these rivers, as well as in the most important lagoons and secondary channels. Three repetitions were made per segment. A population of 1 084 caimans and 503 crocodiles is estimated; for a sight count of 8.64 and 2.80 ind/Km respectively. Speaking of caimans, up to 12 por ciento of individuals of reproductive age were observed, while for crocodiles that number was only 2 por ciento. The abundance of both species in the different places studied, turned out to be significantly different for crocodiles and for caimans (Kruskal-Wallis, P 0.001). Likewise, the size distribution is similar for crocodiles reported in all environments (Kruskal-Wallis, p 0.15), while for caimans it indicates that there is a different distribution for sizes, according to the environment in which they are found (Kruskal -Wallis, P 0.001), with a bias against of the Pacuare and Matina rivers. It was possible to estimate a sex ratio of 1.25 and 0.83 males to females, in crocodiles and caimans respectively, with 9 and 11 captures in that same order, in recruit and juvenile sizes.

Mercury levels and genotoxic effect in caimans from tropical ecosystems impacted by gold mining.

One of the most representative predator species in tropical ecosystems is caiman that can provide relevant information about the impact of mercury (Hg) associated with artisanal and small-scale gold mining. To evaluate the degree to which adverse effects are likely to occur in Caiman crocodilus, total Hg (THg) concentrations in different tissues and DNA damage in erythrocytes were determined. Samples of claws, scutes, and blood were taken from 65 specimens in sites impacted by upstream gold mining, and in a crocodile breeding center as control site, located in a floodplain in northern Colombia. In all the sites, the highest THg among tissues was in the following order: claws >> scutes > blood. High concentrations of THg were found in the different tissues of the specimens captured in areas impacted by mining activities, with mean values in claws (1100 ng/g ww), caudal scutes (490 ng/g ww), and blood (65 ng/g ww), and statistically significant differences compared to those of the control site (p < 0.05). THg in scutes from impacted sites are 15-fold higher than in control, whereas for claws and blood are 8 times higher, and a high significant correlation with THg was found in all the tissues. The comet assay reveals significant differences in the DNA damage in the exposed reptiles compared to the controls (p < 0.01). In sum, C. crocodilus from La Mojana floodplain presents a high ecological risk given its genotypic susceptibility to Hg levels present in its habitat, which could possibly influence vital functions such as reproduction of the species and the ecological niche that it represents within the ecosystem.

Caracterización Morfológica de los Órganos del Sistema Endocrino de la Baba (Caiman crocodilus crocodilus): Aspectos Histológicos / Morphological Characterization of the Organs of the Endocrine System of the Spectacled Cayman (Caiman crocodilus crocodilus): Histological Aspects

Se realizó la descripción histológica de los órganos endocrinos de nueve babas, cinco hembras y cuatro machos (Caiman crocodilus crocodilus), provenientes del Hato Santa Ana, estado Guárico y de la laguna de oxidación de la Facultad de Agronomía de la Universidad Central de Venezuela (UCV), estado Aragua. Las muestras se fijaron en formol neutro al 10% v/v y se incluyeron en parafina en el Laboratorio de Histoquímica de la Facultad de Ciencias Veterinarias de la UCV. Todos los órganos fueron sometidos a la coloración de rutina con hematoxilina y eosina. También, se utilizaron otras coloraciones especiales para la hipófisis como: ácido peryódico de Schiff, tricrómico de Shorr, tricrómico de Gallego y el método de Wilder. Los hallazgos del presente estudio permitieron evidenciar la presencia de la hipófisis, tiroides, paratiroides, glándulas adrenales y la porción endocrina del páncreas, con estructuras bien definidas, como se presentan en otros reptiles, aves y mamíferos; a diferencia de la epífisis, que no se ubicó macroscópicamente. Los hallazgos revelaron que la hipófisis se encontraba organizada de manera similar a otras especies, con una adenohipófisis y una neurohipófisis. La epífisis o glándula pineal no se presentó como un órgano independiente; histológicamente, estuvo representada por células con citoplasma difícil de distinguir y un núcleo redondeado, con nucléolo prominente, a nivel del encéfalo. La tiroides presentó folículos tiroideos y células parafoliculares características. En la glándula paratiroides se evidenciaron las células principales, oxífilas y células similares a las parafoliculares. Las glándulas adrenales mostraron tejido cortical y tejido medular entremezclados. El páncreas mostró tejido linfático asociado, destacándose la porción endocrina, por su agrupación en islotes de Langerhans, constituidos por células con citoplasma pálido, en comparación con las de los acinos.

A histological description of the endocrine organs of nine spectacled caimans (Caiman crocodilus crocodilus) of both sexes, from the Santa Ana farm, in the State of Guárico and the manure lagoon of the Agronomy School of the Universidad Central de Venezuela (UCV), in the State of Aragua, Venezuela, was performed. Samples were fixed in 10% v/v neutral formalin and embedded in paraffin at the Histochemistry Laboratory of the School of Veterinary Medicine of the UCV. All organs were subjected to routine histological staining techniques with hematoxylin and eosin; also, special techniques for the hypophysis such as the periodic acid-Schiff, the Shorr’s trichrome, the Gallego’s trichrome, and the Wilder method were used. The results of the present study showed the presence of the hypophysis, thyroid, parathyroid, adrenal glands, and the endocrine portion of the pancreas, with well defined structures as seen in other reptiles, birds and mammals; unlike the epiphysis, which was not macroscopically identified. The pituitary was organized in a manner similar to other species, with an adenohypophysis and a neurohypophysis. The pineal gland was not seen as an independent body. From the histological stand point, this gland was represented by cells with a difficult to distinguish cytoplasm, with a rounded nucleus, and prominent nucleoli at the brain level. The thyroid showed typical follicles and characteristic parafollicular cells. In the parathyroid gland the main cells, oxyphyl, and parafollicular-like cells were evidenced. The adrenal glands had intermingled cortical and medullary tissues. The pancreas exhibited associated lymphatic tissue, standing out the endocrine portion, due to the clustering of Langerhans islets, made up of cells with pale cytoplasms, compared to those of the acini.

Commercial cuts of Pantanal caiman meat according to sex / Caracterização dos cortes comerciais da carne de jacaré-do-Pantanal em função do sexo

ABSTRACT: This study evaluated the yield, color, and chemical composition of commercial cuts (tail, sirloin cut, back fillet, and thigh) of Pantanal caiman meat in both sexes. The yield of tail was higher than other cuts, and the yield of females (17.0%) was higher than males (15.9%). The thigh of males had lower protein content (20.8%) compared with other cuts. Females showed a higher lipid content in the tail (2.4%) and thigh (0.8%) compared with males (1.7% and 0.4%, respectively). The tail presented the greatest content of monounsaturated fatty acids (45.2%) and higher n6/n3 ratio (4.6). Although lightness was not different among cuts or between sexes, there were differences in color. Males have more yellowish meat compared with females. Thigh and back fillet were more reddish when compared to sirloin cut and tail, regardless of sex. In conclusion, female tail meat provided greater yield and lipid content than males, and this result was statistically significant. These findings can help producers and consumers alike, better understand yield, quality, and nutritional quality of Pantanal caiman meat.

RESUMO: Objetivando avaliar rendimento, cor e composição química dos cortes comerciais (cauda, filé de lombo, filé de dorso e coxa) da carne do jacaré-do-Pantanal nos diferentes sexos, foram processados 20 animais, sendo estes, dez fêmeas (3677g) e dez machos (3510g). Não houve interação significativa (P>0,05) entre cortes comerciais e sexo para peso dos cortes, teor de umidade e cor. O rendimento da cauda foi superior aos demais cortes, sendo o rendimento das fêmeas (17.0%) superior ao dos machos (15,9%). A coxa dos machos apresentou menor teor de proteína (20,8%), em relação aos demais cortes. As fêmeas apresentaram maior teor de lipídeos na cauda (2,4%) e na coxa (0,8%), em relação aos machos (1,7% e 0,4%, respectivamente). A cauda apresentou maior quantidade de ácidos graxos monoinsaturados (45,2%) e maior razão n6/n3 (4,6). A luminosidade não foi diferente entre cortes e sexos. Os machos apresentaram carne com coloração mais amarelada em relação às fêmeas, e a coxa e o filé de dorso tiveram cor mais avermelhada, comparadas ao filé de lombo e cauda, independente do sexo. Concluiu-se que houve influência do sexo no corte de cauda, para o teor de lipídios e rendimento, sendo que a fêmea apresentou rendimento e lipídeos maiores que o macho.

Genetic Evidence for Polygamy as a Mating Strategy in Caiman crocodilus.

The mating system of the spectacled caiman (Caiman crocodilus) was investigated in the Piagaçu-Purus Sustainable Development Reserve, Amazonas, Brazil. We used 6 polymorphic microsatellite loci to genotype 13 females and 174 hatchlings representing 20 nests sampled over 4 consecutive reproductive seasons (2007-2010). Paternity was determined by 2 methods: simple counts, and statistical analysis using Gerud 2.0. Results were congruent between the 2 approaches, and the null hypothesis of single paternity was rejected in 19 of the 20 nests analyzed, thereby demonstrating that C. crocodilus females are polyandrous and that the breeding system of the species can be characterized as polygamous. The data suggest that 1-4 fathers were responsible for the paternity of the offspring, and that the males contributed differently (9-100%) to each of the 20 nests. A total of 53 males copulated with the 20 females mothering the nests. This is the first study on the mating system of C. crocodilus and the frequency of multiple paternity is among the highest values (95%) reported thus far for crocodilians.

Physico-chemical and sensory attributes of low-sodium restructured caiman steaks containing microbial transglutaminase and salt replacers.

Our objective was to examine the physico-chemical and sensory attributes of low-sodium restructured caiman steaks containing microbial transglutaminase (MTG) and salt replacers (KCl and MgCl2). Trimmings from caiman carcasses were processed into restructured steaks with or without MTG and salt replacers; the five treatments were CON (1.5% NaCl), T-1 (1.5% NaCl+1% MTG), T-2 (0.75% NaCl+1% MTG+0.75% KCl), T-3 (0.75% NaCl+1% MTG+0.75% MgCl2), and T-4 (0.75% NaCl+1% MTG+0.375% KCl+0.375% MgCl2). T-4 demonstrated the greatest (P<0.05) succulence and the lowest (P<0.05) values for cooked hardness, springiness, and cohesiveness. The greatest (P<0.05) purchase intention was for T-3. Furthermore, T-3 and T-4 were similar (P>0.05) to controls in salty flavor. Our findings suggest that the combination of MTG, KCl, and MgCl2 can be employed as a suitable salt reduction strategy in restructured caiman steaks without compromising sensory attributes and consumer acceptance.

Evaluación del desarrollo de babas (Caiman crocodilus crocodilus) alimentadas con una dieta medicada con antibiótico / Evaluation of development of the spectacle caiman (Caiman crocodilus crocodilus) fed with an antibiotic medicated diet

La baba, Caiman crocodilus crocodilus, criada en cautiverio puede sufrir estrés, que unido a otros factores, promueve el retraso y mortalidad en la época crítica de crecimiento, por lo que algunos algunos autores reportan el uso de antibióticos para contrarrestar estos efectos. Se evaluó el crecimiento de babas en cautiverio alimentadas con una dieta medicada con antibiótico (virginiamicina) y poblaciones con dieta no medicada, tomando como indicadores: medidas del largo total, grosor del cuello y grosor de la base de la cola y el peso de los animales. Se utilizaron 600 babas nacidas por incubación en el zoocriadero Kiubo (La Suareña, estado Aragua). Estos animales fueron medidos, pesados y evaluados clínicamente antes del inicio del ensayo y distribuidos al azar en un tanque tipo australiano (4 secciones). Las dietas fueron: Tratamiento 1: alimento comercial + proteína animal fresca, y Tratamiento 2: alimento comercial + antibiótico + proteína animal fresca. El análisis estadístico fue un diseño completamente aleatorizado, con evaluaciones en tres etapas o fases: Inicial, Intermedia y Final. En la fase inicial se encontraron diferencias significativas (P≤ 0,05) para todas las variables, siendo el tratamiento 1 el que resultó con mayores promedios. En la fase intermedia se observaron diferencias significativas (P≤0,05) para grosor de la base de la cola, largo total y peso; el grosor del cuello no presentó diferencia significativa. En la fase final se, detectaron diferencias significativas (P≤0,05) entre los tratamientos para la base de la cola y largo total; para el grosor del cuello y peso no hubo diferencias significativas. Se observó que el tratamiento 1 fue mejor que el tratamiento 2, para algunas variables, pero ambas dietas contribuyeron al incremento de la tasa de crecimiento, concluyéndose que no se recomienda el uso de antibióticos adicionados a la dieta, ya que incrementa los costos de producción y puede contribuir con la resistencia bacteriana en el hombre, mientras la cría en cautiverio de esta especie, depende principalmente del buen manejo de los mismos.

The spectacled caiman (Caiman crocodilus crocodilus) is a species raised in captivity that can suffer from stress, which, along with other factors, promotes growth delay and mortality during the critical time of growth. Some investigators report the use of antibiotics to counteract those effects. The growth of a population of spectacle caimans raised in captivity and fed with a diet supplemented with antibiotic (virginiamycin) was compared with the growth of the spectacle caiman population fed with a control diet was assessed. A total of 600 animals born through incubation at the Kiubo farm were used. Before the onset of the experiment, the animals were measured, weighed, clinically evaluated, and randomly distributed in four sections in an Australian tank. The following variables were measured using a metric tape: total length (TL), neck thickness (NT), base of the tail thickness (BTT). The weight was recorded with an electronic balance. The animals were submitted to the following treatments (T): Treatment 1 (T1): commercial diet + fresh animal protein; Treatment 2 (T2): commercial diet + fresh animal protein + antibiotic. The evaluations were carried out in three phases: Initial phase, Intermediate phase, and Final Phase. A totally randomized design with a covariance analysis was performed to analyze the data. The results show that during the initial phase, all variables showed statistically significant (P≤0.05) differences, reaching T1 the highest averages. During the intermediate phase, significant differences (P≤0.05) were found for BTT, TL, and weight. The NT was not significant. During the final stage, statistical differences (P≤0.05) were recorded among T for BTT and TL, but no differences were found for NT and weight. For some variables, T1 was better than T2, but both diets contributed to the increment of growth rate. It is concluded that the use of antibiotics supplemented in the diet, increases production costs and that breeding in captivity depends more on good handling.

Caracterización morfológica e histoquímica del hígado de la baba (Caiman Crocodilus Crocodilus) / Morphological and Histochemical Characterization of the Liver of the Spectacled Cayman (Caiman crocodilus crocodilus)

La morfología, organización y los componentes intracitoplasmáticos del hepatocito de la baba (Caiman crocodilus crocodilus) son aspectos que se han estudiado parcialmente hasta el momento. Con el fin de generar información sobre la morfología microscópica del hígado de esta subespecie, se realizó un estudio descriptivo de las características morfológicas e histoquímicas del hígado de la baba, lo que permitirá la comprensión de algunas funciones hepáticas en estos ejemplares. De esta manera, se podrán realizar en el futuro, investigaciones utilizando a dicho órgano como modelo experimental para el estudio de las rutas metabólicas de los metabolitos procesados a este nivel. Se tomaron ocho muestras de hígado, se fijaron en formol al 10%  y se procesaron por los métodos histológicos de coloraciones de rutina (Hematoxilina y Eosina). Asimismo, se utilizaron las coloraciones especiales de Tricrómico de Gallegos, el método de Wilder y el aceite rojo “O”. Los hallazgos del presente trabajo revelaron la presencia de un hígado bilobulado, ubicado en la cavidad celómica caudal, con los  lóbulos derecho e izquierdo unidos por un istmo. El órgano se encuentra rodeado por una delgada cápsula de tejido conectivo, su parénquima se dispone en cordones tortuosos con un patrón acinar, con presencia de células pigmentadas compatibles con melanóforos, dispersas en el tejido hepático, y con gotas lipídicas intracitoplasmáticas de diversos tamaños, que en algunos casos ocupaban casi la totalidad del citoplasma de los hepatocitos.

The morphology, organization and intracytoplasmic components of the liver of the spectacled cayman (Caiman crocodilus crocodilus) are aspects that have been partially studied so far. A descriptive study of the morphological and histochemical characteristics of the liver of this subspecies was performed. This investigation would enable researchers to understand the liver functions in these animals, thus allowing future research using this organ as an experimental model. Eight liver samples were fixed in 10% v/v formalin and processed by conventional histology using routine hematoxylin and eosin staining. Additionaly, special stains, such as the Trichrome of Gallegos method and the red oil “O” and Wilder, were also used. The findings revealed the presence of a bilobed liver located in the midline of the caudal coelomic cavity, surrounded by a thin capsule of connective tissue; the parenchyma showed the layout of the classic hepatic lobule, the hepatocytes were arranged in tortuous cords and an acinar pattern. The presence of pigment-laden cells compatible with melanophores scattered in liver tissue was evidenced. Intracytoplasmic lipid droplets of various sizes occupying almost the entire cytoplasm of the hepatocytes were observed.

Características histológicas del epidídimo de Baba (Caiman crocodilus crocodilus) sexualmente maduro / Histological characteristics of the epididymis of the sexually mature spectacled Caiman (Caiman crocodilus crocodilus)

El epidídimo es un órgano que forma parte del aparato reproductivo masculino en todas las especies vertebradas, y que posee características histológicas que permiten lograr su identificación. Se realizó el estudio histológico del órgano reproductor de las babas Caiman crocodilus crocodilus en diferentes meses del año, incluyendo las épocas de gran actividad sexual o apareamiento y la época de no apareamiento, para conocer si las características histológicas de este órgano son similares durante todo el año. Se extrajeron 11 ejemplares sexualmente maduros de su medio ambiente natural, obteniéndose por necropsia, las muestras del epidídimo. Las muestras se fijaron con formol buferado al 10%, y se incluyeron en parafina. Posteriormente, se realizaron cortes de 5µm de grosor y fueron teñidos con Hematoxilina - Eosina. Como característica histológica común durante todo el año, se observó la presencia de unos conductillos epididimarios que confluyen en un conducto principal o conducto del epidídimo con un epitelio que varió de cúbico simple en la porción anterior a cilíndrico simple en los segmentos medio y posterior. De igual manera, se apreció un aumento de la capa muscular a medida que se avanzaba hacia las porciones media y posterior. En época de apareamiento resalta la característica del epitelio visiblemente festoneado, el aumento en la altura del mismo, la presencia de un gran número de células claras sin estereocilios y el aumento del diámetro de los conductos, así como gránulos de secreción eosinofílicos y un gran número de espermatozoides en el lumen, detalle que no es observado en la época de no apareamiento, durante la cual no se observa el epitelio de forma festoneado y su diámetro es mucho menor.

The epididymis is an organ which forms part of the male reproductive tract in all vertebrate species, and it possesses histological characteristics which allow its identification. A study was conducted to verify if the histological characteristics of the epididymis of the spectacled caiman (Caiman crocodilus crocodilus) are similar during different seasons of the year, including seasons of high and low mating activity. A total of 11 mature animals were selected from their natural environment. Samples of the epididymis were obtained from necropsy, fixed with 10% buffered formaldehyde and embedded in paraffin. Subsequently, they were stained with hematoxilin-eosin. The results show a common histological characteristic: the presence of some epididymis tiny ducts that converge into a main duct or the epididymis duct, with an epithelium which varies from a simple cubic in the anterior portion to a cylindrical one in the medial and posterior segments. In a similar way, as one moves forward to the medial and posterior portions, an increase in the muscular layer is observed. During mating time, the visibly festooning of the epithelium, the increase in height, the presence of a large amount of clear cells without stereocilium, an increase in the diameter of the ducts, as well as eosinophillic secretion granules and a great quantity of sperms in the lumen, stand out, a detail which is not seen during non-mating season, where the presence of a festooned epithelium is not observed, and its diameter is much smaller.

Descripción morfológica de las células sanguíneas de la Baba / Morphologycal Description of Blood Cells of the Baba

La “baba”, Caiman crocodilus crocodilus, es una especie que ha existido desde hace mas de 200 millones de años y manteniéndose sin variaciones durante el tiempo. El estudio de la morfología y las dimensiones celulares es de gran utilidad al comparar e interpretar los hemogramas desde el punto de vista clínico patológico. Con el objetivo de estudiar las dimensiones y morfología de las células sanguíneas, se tomaron 100 animales del medio ambiente en la zona de Guaritico, estado Apure, con edades comprendidas entre 2 a 5 años, de los cuales se obtuvieron muestras de sangre completa en tubos con EDTA, para ser procesadas en el laboratorio. Se realizaron frotis de las muestras que fueron teñidos con Giemsa, para analizar las características morfológicas de cada grupo celular. Se utilizaron para la medición, plantillas de acetato con agujeros al azar y se tomaron fotos de los campos para ser sometidas al programa morfométrico Sigma Scan Pro 5, el cual discrimina el tamaño celular de la siguiente manera: eritrocitos: 12,5-19,5 µm; heterófilos: 11,3-18,5mm; eosinófilos: 11,5-14,9mm; basófilos: 12,7-16,0 mm; linfocitos: 6,5- 8,9mm; monocitos: 9,4-14,6 mm, respectivamente. En el caso de los trombocitos, el tamaño fue 9,3-12,0 mm. La morfología de las diferentes células coincide con la descrita para el Alligator mississippiensis, Caiman crocodilus yacare, Caiman crocodilus lacostris, la Agrionemys horsfieldi y en otros reptiles.

The Caiman crocodilus crocodiles is a species that has existed in nature for over 200 million years and has practically remained unchanged during this time. From the clinical pathological point of view, the morphological studies as well as the cellular dimensions are of great usefulness when describing and comparing hemograms. The aim of this investigation was to study the dimensions and morphology of blood cells. A sample of 100 animals from a wildlife reserve in Guaritico region, in the State of Apure, aged 2 to 5 years, was taken. Samples of whole blood using EDTA tubes were obtained and processed in the laboratory. Blood smears were stained with Giemsa and the morphological characteristics of each cellular group were analyzed. For measuring cell dimensions, randomly distributed holes were punched to acetate templates. Subsequently, photographs of the fields were taken and analysed using the Sigma Scan Pro 5 morphometric program. Results show the size of the different cells: erythrocytes: 12,5-19,5 µm; heterophils: 11,3-18,5 mm; eosinophils: 11,5-14,9mm; basophils: 12,7-16,0 mm; lymphocyte: 6,5- 8,9 mm; monocytes: 9,4-14,6 mm, respectively and thrombocytes 9,3-12,0 mm. The morphology of these different blood cells coincides with that described for the Alligator mississippiensis, Caiman crocodilus yacare, Caiman crocodilus lacostris, the Agrionemys horsfieldi and other reptile species.

Morfología de las vías urinarias de la baba macho (Caiman crocodilus crocodilus) / Morphology of the urinary pathway’s of the male spectacled cayman (Caiman crocodilus crocodilus)

Con el fin de establecer las características morfológicas de las vías urinarias del Caiman crocodilus crocodilus, se realizó el estudio morfológico de las vías urinarias de nueve babas macho adultas, usando las coloraciones Hematoxilina-Eosina y Tricrómica de Mallory. Se concluye que la presencia de túnica muscular a partir de los túbulos colectores puede relacionarse con la necesidad de movilizar pequeñas cantidades de orina cargada de uratos precipitados mediante movimientos peristálticos, lo cual se asociaría con la necesidad de este reptil de producir volúmenes reducidos de orina isosmótica, por lo cual se reduce la pérdida de líquido a nivel renal. Posiblemente, esto implica la secreción de mucinas lubricantes a lo largo de vías urinarias, como un mecanismo facilitador del transporte de los uratos precipitados.

A study was conducted with the purpose of establishing the morphologic characteristics of the urinary pathway of the male spectacled caiman (Caiman crocodilus crocodilus). A total of nine adult caimans were used. Samples of the urinary tract were collected and stained with Hematoxilyn-Eosin and Mallory’s trichromic stains. The results of the present study reveal that the presence of a muscular layer, departing from the collecting tubules, could be associated to the need of mobilizing small amounts of urine loaded with precipitated urates, by means of peristaltic movements, which may be associated with the need of this reptile of producing reduced volumes of isosmotic urine. This would lead to a reduction of fluid loss at a renal level. This possibly implies the secretion of mucines along the urinary tract, as a facilitator mechanism for the transport of precipitated urates.

Histoquímica de mucinas y lípidos del aparato urinario de la baba (Caiman crocodilus crocodilus) / Mucins and Lipids Histochemistry of the Urinary System in the Spectacled Cayman (Caiman crocodilus crocodilus)

Se realizó un estudio histoquímico de mucinas y lípidos del aparato urinario de nueve babas adultas de sexo masculino y de un ejemplar adulto de sexo femenino, utilizando las coloraciones PAS, PAS-Azul alciano a pH 2,5 y 1,0; Aceite Rojo “O” y el Método de Schulz para esteroides. Los hallazgos más relevantes fueron la presencia de mucinas neutras en el borde en cepillo y  gotas citoplasmáticas de todos los túbulos de la nefrona y en la superficie apical del urotelio, así como presencia de sialomucinas desde el túbulo distal hasta el uréter. Se detectaron gotas lipídicas compuestas por ácidos grasos libres en el citoplasma de las células del segmento intermedio de la nefrona. Se discute la importancia de estas mucinas como protectores de las mucosas y como lubricantes de las vías urinarias. Estos estudios parecen demostrar la ausencia de porciones de la nefrona del Caiman crocodilus crocodilus que intervengan en la secreción de líquido seminal o que sean análogos del segmento sexual de los lagartos y serpientes.

A histochemical study of mucins and lipids of the urinary tract of the spectacled caiman was conducted, using PAS stain, PAS-Alcian blue stain (at pH values of 2.5 and 1.0, respectively), “O” red oil stain, and Shultz method for steroids. Nine mature males and one mature female were used. The results of the present study show that the most relevant findings were the presence of neutral mucins in the brush border and of cytoplasmic droplets in all tubular nephrons and in the apical surface of the urothelium, as well as the presence of sialomucins from the distal tubule to the ureter. Lipid droplets composed of free fatty acids were observed in the cytoplasm of the cells of the intermediate segment of the nephron. The importance of mucins as mucosal protectors and urinary tract lubricants is discussed. The results of the study in the Caiman crocodilus crocodilus, appear to demonstrate the absence of portions of the nephron that either participate in the secretion of seminal fluid or are similar to the sexual segment of lizards and snakes.

Histología del Riñón de la Baba (Caiman crocodilus crocodilus) / Histology of the Spectacled Caiman Kidney (Caiman crocodilus crocodilus)

Tras haberse reportado similitudes estructurales entre las nefronas de dos especies de crocodílidos poco relacionadas taxonómicamente, pero con hábitat similar, Caiman crocodilus crocodilus y Crocodilus acutus, y con el fin de determinar si estas estructuras ofrecen a C. c. crocodilus cierta ventaja en su capacidad de adaptación al hábitat, se llevó a cabo el estudio histológico del riñón de nueve babas macho adultas y de una hembra adulta, usando las coloraciones Hematoxilina-Eosina y tricrómica de Mallory. Entre otros hallazgos, se demostró la existencia de estructuras histológicas que permiten sugerir la presencia del aparato yuxtaglomerular en esta especie.

Structural similarities have been reported between the nephrons of two crocodrilian species (Caiman crocrodilus crocrodilus and Crocodilus acutus) not taxonomically related, but with a similar habitat. A histological study of the kidney was conducted to determine if these structures give the C. c crocodiles certain advantages in its capacity for adaptation to the habitat. Nine adult male and one adult female caimans were used in the study. Samples were stained with hematoxilin-eosin and Mallory’s tricromic stains. The results of the present study reveal the presence of microscopic structures that suggest the existence of a juxtaglomerular apparatus in this species.

Características histológicas del aparato genital masculino de la baba (caiman crocodilus crocodilus). / Histological Characteristic of the Masculine Genital System of the Spectacled Cayman (Caiman crocodilus crocodilus).

Se realizó la descripción histológica del aparato genital masculino de 9 babas adultas salvajes (Caiman crocodilus crocodilus), provenientes de los Llanos de Apure, Venezuela; las muestras obtenidas mediante necropsia, fijadas en formol al 10% amortiguado a pH 7,0 y procesadas mediante la técnica de inclusión en parafina, fueron teñidas con la coloración de rutina Hematoxilina-Eosina y con la coloración Tricrómica de Mallory. Los hallazgos más importantes fueron: gran actividad espermatogénica; evidencia de gránulos de secreción acidófilos en algunos casos, y sin afinidad tintorial en otros, en diferentes segmentos del epidídimo, presencia de glándulas de secreción mucosa en el surco eyaculador y gran cantidad de tejido eréctil a nivel de este surco y a lo largo del pene.

An histological description of the male genital apparatus of 9 mature wild spectacled caimans (Caiman crocodilus crocodilus) from Apure Plains, Venezuela, was carried out; the samples obtained by necropsy were fixed in formalin to 10% buffered to pH 7.0 processed by means of the paraffin inclusion technique and stained with the routine Haematoxylin-Eosin and Mallory’s Tricromic stains. The most important discoveries were: great spermatogenic activity, evidence of granules of secretion whit acid-stain affinity in some cases, and without stain affinity in others, in different segments of the epididymis, presence of glands of mucous secretion in the ejaculatory groove, and great quantity of erectile tissue at level of this groove and along the penis.