Functional morphology and fiber types of the masseter muscles of two caviomorph rodents with contrasting lifestyles, Ctenomys talarum (Ctenomyidae) and Cavia aperea (Caviidae).

The aim of this work is the analysis of histochemical and morphometric properties of the masseter muscles of Ctenomys talarum and Cavia aperea. The former belongs to a subterranean rodent clade, Ctenomyidae, which has evolved a robust masticatory apparatus adapted to chisel-tooth digging and processing of abrasive grasses; C. aperea belongs to the family Caviidae, with relatively graceful jaws and mandibular musculatures, consistent with less mechanically challenging diets. Adult males were captured, immediately transported to the laboratory, and euthanized in a CO2 chamber. The musculus masseter superficialis and musculus masseter profundus on the left side of the animals were used to analyze the histochemical composition of the fiber types treated with myosin adenosine triphosphatase, succinate dehydrogenase and periodic acid Schiff. The mean fiber diameters, relative areas, and frequencies of each muscle fiber type were calculated. The mm. masseter superficialis and masseter profundus on the right side were used to measure the physiological cross-sectional area (PCSA). Based on this measurement, the internal force (F) was estimated. In the m. masseter profundus of both species and in the m. masseter superficialis of C. aperea intermediate fast oxidative-glycolytic fibers (FOGi) predominated. In the mm. masseter superficialis and masseter profundus of C. talarum the relative area of fast glycolytic (FG) fibers was greater than that of the muscles of C. aperea, whose main muscle fiber component is FOGi fibers. When corrected for body mass differences, PCSA was higher for the mm. masseter superficialis of C. talarum. This and the larger relative area of FG fibers, probably contributes to the exertion of large bite forces in C. talarum, as measured in previous studies.

Effect of anodized zirconium implants on early osseointegration process in adult rats: a histological and histomorphometric study.

Since surface plays a key role in bioactivity, the response of the host to the biomaterial will determine the success or failure of the prosthesis. The purpose of this study is to make an exhaustive analysis of the histological and histochemical characteristics of new bone tissue around Zr implants anodized at 60 V (Zr60) supported by histomorphometric methods in a rat model. Fibrous tissue was observed around the control implants (Zr0) and osteoblasts were identified on the trabeculae close to the implantation site that showed typical cytological characteristics of active secretory cells, regardless of the surface condition. The histomorphometrical analysis revealed a significant increase in cancellous bone volume, trabecular thickness and in trabecular number together with a decrease in trabecular separation facing Zr60. TRAP staining showed that there was a relative increase in the number of osteoclasts for Zr60. In addition, a larger number of osteoclast with a greater number of nuclei were detected in the tibiae for Zr60. This research demonstrated that the new bone microarchitecture in contact with Zr60 is able to improve the early stages of the osseointegration process and consequently the primary stability of implants which is a crucial factor to reduce recovery time for patients.

Analysis of glycoconjugates and morphological characterization of the descending colon and rectum of the plains viscacha, Lagostomus maximus.

Herbivores exhibit specializations at the intestinal level that facilitate the bacterial fermentation. The available information on the digestive physiology of Lagostomus maximus makes this rodent an interesting model to evaluate morpho-functional adaptations to herbivory. The general objective of this work was centered on the study of the morphology and histochemistry of the descending colon and rectum of L. maximus. To do so, a comparative analysis of the morphology, ultrastructure and glycosylation pattern of both anatomical regions was carried out. Histochemical results revealed that in both sectors of the large intestine, there are goblet cells with different glycosylation pattern within a morphologically homogeneous cell population. The main difference between both intestinal segments lay in the fact that the most distal region of the large intestine showed a greater proportion of sialomucins, characterized by being slightly O-acetylated. Further specific differences were revealed by lectin histochemistry. These data allowed to perform a functional interpretation of the cell types and secreted substances, thus contributing to a better understanding of the role of mucins in the intestinal tract functioning.

Histological development of the long-snouted seahorse Hippocampus guttulatus during ontogeny.

The objective of the present study was to describe histological development of the European long-snouted seahorse Hippocampus guttulatus, to increase understanding of the biology and physiology of the species. Most vital organs were present in juveniles by the time of their release from the male's pouch. Digestive tract specialization occurred at 89 effective day-degrees (D°eff ), corresponding to 15 days post partum (dpp), with development of the first intestinal loop and mucosal folding. At 118 D°eff (20 dpp), lipids were being mobilized from the liver and oocytes attained the perinuclear stage. The fovea emerged at 177 D°eff (30 dpp), contemporaneous with the shift from pelagic to benthic behaviour in juveniles. At this stage, the most interesting feature was the formation of the second intestinal loop. Male gonads were never observed during the study (from 0 to 354 D°eff ; 0-60 dpp), but the first oogonia were present at 30 D°eff (5 dpp). In 354 D°eff (60 dpp) juveniles, oocytes were observed in a cortical alveoli stage, indicating maturity. Low digestive efficiency was observed at early stages, which was due to a poorly developed gastrointestinal tract and an immature digestive tract prior to 89 D°eff . The present study demonstrates that approximately 89 and 177 D°eff represent two important transitional stages in the early development of H. guttulatus. At a temperature of approximately 19 ± 1°C and an age of 1 month (177 D°eff ), main organs were fully functional, suggesting that the adult phenotype was largely established by that age, with females becoming mature at the age of 2 months (354 D°eff ).

The colonic groove of the plains viscacha (Lagostomus maximus): Histochemical evidence of an abrupt change in the glycosylation pattern of goblet cells.

The ascending colon of most rodent species shows a longitudinal colonic groove that works as a retrograde transport pathway for a mixture of bacteria and mucus toward the cecum. We describe the morphology and glycosylation pattern of the colonic groove of Lagostomus maximus to analyze the role of mucins in this anatomical feature. We also studied the distribution pattern of the interstitial cells of Cajal (ICC) to evaluate their regulatory influence on gut motility. The groove originated near the cecocolic junction and extended along the mesenteric side of the ascending colon, limited at both ends by nonpapillated ridges. These ridges divided the lumen of the ascending colon into two compartments: a narrow channel and a large channel, called the groove lumen and the main lumen, respectively. The histochemical analysis showed differences in the glycosylation pattern of the goblet cells inside and outside the groove. Unlike the mucosa lining the main lumen of the colon, the groove was rich in goblet cells that secrete sulfomucins. The PA/Bh/KOH/PAS technique evidenced an abrupt change in the histochemical profile of goblet cells, which presented a negative reaction in the groove and a strongly positive one in the rest of the colonic mucosa. The anti-c-kit immunohistochemical analysis showed different ICC subpopulations in the ascending colon of L. maximus. Of all types identified, the ICC-SM were the only cells located solely within the colonic groove.

Influence of reduced salinity on the histochemical fiber type composition of the claw closer muscle of two estuarine crab species, Cyrtograpsus angulatus and Neohelice granulata (Decapoda: Varunidae) / Influencia de la salinidad reducida sobre la composición histoquímica de tipos de fibras del músculo de cierre de las quelas de dos especies de cangrejos estuariales, Cyrtograpsus angulatus y Neohelice granulata (Decapoda: Varunidae)

The estuarine crustaceans are exposed to frequent and abrupt environmental salinity changes that involve adjustments at different levels in muscle tissue. The histochemical composition of fiber types of the claw closer muscle of Cyrtograpsus angulatus and Neohelice granulata (Dana, 1851) under hyper regulatory conditions was analyzed. Cryosections of the muscle were treated with myosin-adenosine triphosphatase (m-ATPase), succinic dehydrogenase (SDH), periodic acid Schiff (PAS) and Sudan Black B. The mean diameters, the relative area and the proportion of each muscle fiber type were calculated. Types I and IV would belong to 'extreme' groups, whereas types II and III would be considered 'intermediate'. Type I fibers were large and exhibited a weak reaction to all techniques; type IV fibers were small and reacted strongly to histochemical tests. Types II and III prevailed in C. angulatus whereas type II predominated in N. granulata. Type IV fibers were absent in C. angulatus and scarce in N. granulata. The claw closer muscle of N. granulata and C. angulatus exhibited differential responses under reduced salinity at a histochemical level. Therefore, the existence of different adjustment mechanisms facing salinity stress is suggested.

Los crustáceos estuariales están expuestos a cambios frecuentes y abruptos en la salinidad ambiental que requieren ajustes a diferentes niveles en el tejido muscular. Se analizó la composición histoquímica de tipos de fibras del músculo de cierre de las quelas de Cyrtograpsus angulatus y Neohelice granulata (Dana, 1851) en condiciones de hiperregulación. Secciones de crióstato fueron tratadas con miosín-adenosín trifosfatasa (m-ATPasa), succinato deshidrogenasa (SDH), ácido periódico Schiff (PAS) y Sudan Black B. Se calcularon el diámetro promedio, el área y la proporción relativa de cada tipo de fibra. Los tipos I y IV serían grupos "extremos", mientras que los tipos II y III "intermedios". Las fibras del tipo I, de gran tamaño, exhibieron una reacción débil con todas las técnicas; las fibras del tipo IV, pequeñas, reaccionaron intensamente frente a los tests histoquímicos. Los tipos II y III predominaron en C. angulatus, mientras que el tipo II fue el más abundante en N. granulata. Las fibras del tipo IV fueron escasas en N. granulata y no se observaron en C. angulatus. El músculo de cierre de las quelas de N. granulata y C. angulatus exhibió respuestas diferenciales a nivel histoquímico en condiciones de salinidad reducida. De este modo, se sugiere la existencia de diferentes mecanismos de ajuste frente al estrés salino.

Comparative Analysis of the Morphology, Ultrastructure, and Glycosylation Pattern of the Jejunum and Ileum of the Wild Rodent Lagostomus maximus.

Morphological and histochemical analyses were performed to characterize the histology, ultrastructure, and glycosylation pattern of the jejunum and ileum of the wild rodent Lagostomus maximus. Enterocytes, goblet cells, Paneth cells, and enteroendocrine cells were identified in both intestinal epithelia. Two morphological types of enterocytes were identified only in the ileum based on their cytoplasm electron density. Although the histological and ultrastructural examination showed that the epithelia of both anatomical regions were morphologically similar, a certain specialization in their secretory products was evident. The glycosylation pattern of the jejunum and ileum was characterized in situ by histochemical and lectin histochemical methods. Histochemical results revealed the presence of carboxylated and sulfated gycoconjugates in both regions, although sulfomucins were clearly prevalent in the ileum. Sialic acid was highly O-acetylated and particularly abundant in the jejunum. The KOH/PA*/Bh/PAS technique evidenced a more intense histochemical reaction in the jejunal than in the ileum goblet cells, demonstrating a reduction of neutral mucin secretion in the distal small intestine. Further specific differences were revealed by lectin histochemistry. These data evidenced that the nature of mucus varies at different anatomical regions, probably adapted to physiological requirements.

Comparative analysis of the morphology and histochemistry of the duodenum of the coypu (Myocastor coypus bonariensis) during its prenatal and postnatal development.

The objective of this study focused on the comparative morphological and histochemical analysis of the duodenum of fetuses, juveniles and adult coypu (Myocastor coypus bonariensis), the major socioeconomic wildlife resource of Argentina. Histological and histochemical procedures for in situ characterization of glycoconjugates (GCs) were used. This study evidenced that fetal mucins differ histochemically in many respects from their adult counterparts. Only in fetuses from 90 days-post coitus (dpc) glycogen-rich sites were observed throughout the duodenal epithelium. The goblet cells appeared from 105 dpc and their secretory content varied considerably after birth. Duodenal glands presented scanty neutral and sulphated GCs in the 30-day juveniles; in adults the proportion of these GCs increased, and carboxylated and sialylated GCs were also observed. The results obtained in this work may be used in future studies to evaluate the effects of diet and intestinal pathologies in the glycosylation pattern of GCs. Also, knowledge of the normal glycoprofile of the duodenum of M. coypus bonariensis during its ontogenetic development may constitute a basis for the study of this organ in other Hystricognathi rodents.

Histological and Histochemical Study of the Hepatopancreas of Two Estuarine Crab Species, Cyrtograpsus angulatus and Neohelice granulata (Grapsoidea, Varunidae): Influence of Environmental Salinity.

The aim of this study was to analyze the histology and the histochemical distribution of glycoproteins (GPs) and lipids of the hepatopancreas of Cyrtograpsus angulatus and Neohelice granulata acclimated to salinities of 10 psu (hyperregulation) and 35 psu (osmoconformation). Sections of the hepatopancreas of adult male crabs were treated with hematoxylin-eosin; Masson trichrome; Alcian Blue (pHs 2.8, 1.0, 0.5); Toluidine Blue (pHs 5.6, 4.2); periodic acid Schiff; Sudan Black and Red. At salinity 35 psu, the hepatopancreas of both species exhibited typical histological features, whereas at salinity 10 psu, detachment of the basal lamina, desquamated epithelium, disrupted brush border, loss of intercellular cohesion, hypertrophied tubular lumen, and hemolymph infiltration between cells were observed in some zones. Resorptive cells (R-cells) and vacuoles of blister-like cells (B-cells) of both species show a higher glycogen content at 35 psu than at 10 psu. At lower salinities, the cytoplasm of the different cell types evidence higher contents of carboxylated GPs in N. granulata and of su If at ed GPs in C. angulatus. At both salinities, and at the two pHs in N. granulata and at pH 5.6 in C. angulatus, the brush border, the vacuoles of B-cells and the peritrophic membrane show metachromasia. R-cell vacuoles and the cytoplasm of all cell types--except for the E-cells--at all salinities in both species show abundant lipid droplets. The results of the present study contribute significant data to the histophysiology of crustacean decapods, favoring the comprehension of the complex adjustment mechanisms facing saline stress in euryhaline crabs.

Surface ultrastructure of the gills of Odontesthes bonariensis (Valenciennes, 1835)(Teleostei: Atheriniformes) from a temperate shallow lake / Estudio ultraestructural de las branquias de Odontesthes bonariensis (Valenciennes, 1835) (Teleostei: Atheriniformes) de un lago somero templado

We studied the gill epithelium of juveniles of Odontesthes bonariensis using scanning electron microscopy with a particular interest in the relationship between cell morphology and the different functional aspects of gills. The specimens used were collected in Laguna de los Padres, Buenos Aires Province, Argentina. The gill filaments or primary lamellae are arranged in two rows along the convex outer face of the gill arch forming the anterior and posterior hemibranchiae. On its concave inner face, each arch supports two rows of gill rakers forming the pharyngeal region wall. The primary lamellae are lined by a stratified epithelium made up of polygonal cells with well-defined outlines and cell membrane microfolds. Several mucous and chloride cells were observed in the primary lamellae. The epithelial cells of the secondary lamellae have ill-defined outlines and few microfolds. Both the arches and gill rakers are covered by a stratified epithelium of polygonal cells, among which mucous cells and taste corpuscles are abundant. The ultrastructural analysis of gills of O. bonariensis contributes to the advancement of knowledge of the organ histophysiology and of future histopathological studies.

Se estudió el epitelio branquial de juveniles de Odontesthes bonariensis utilizando microscopía electrónica de barrido con un interés particular en la relación entre la morfología celular y los distintos aspectos funcionales de las branquias. Los ejemplares utilizados fueron colectados en la Laguna de los Padres, Provincia de Buenos Aires, Argentina. Los filamentos branquiales o laminillas primarias están dispuestos en dos filas a lo largo de la cara exterior convexa del arco branquial formando las hemibranquias anterior y posterior. En su cara interior cóncava, cada arco sostiene dos hileras de branquiespinas que forman la pared de la región faríngea. Las laminillas primarias están revestidas por un epitelio estratificado constituido por células poligonales con contornos bien definidos y micropliegues de la membrana celular. Se observaron numerosas células clorhídricas y mucosas en las laminillas primarias. Las células epiteliales de las laminillas secundarias tienen contornos poco definidos y escasos micropliegues. Tanto los arcos como las branquiespinas están cubiertos por un epitelio estratificado de células poligonales, entre las cuales hay abundantes células mucosas y corpúsculos gustativos. El análisis ultraestructural de las branquias de O. bonariensis proporciona información para avanzar en el conocimiento de la histofisiología del órgano y para realizar futuros estudios histopatológicos.

Morphology of the claw closer muscle in two estuarine crab species (Crustacea, Varunidae): an ultrastructural study.

We analyzed the ultrastructural features of the claw closer muscles in two estuarine crabs, Cyrtograpsus angulatus and Neohelice granulata, by transmission electron microscopy. Adult male crabs at intermolt stage were collected in the Mar Chiquita Coastal Lagoon (Buenos Aires, Argentina). The muscle fibers of both species showed evident striations, peripheral and intermyofibrillar nuclei, clefts in continuity with T and Z tubules, sarcoplasmic reticulum and T tubules forming dyads and triads usually located between the A and I bands, and mitochondria located mainly beneath the sarcolemma. Glycogen was observed as diffuse, small particles among myofilaments. The claw closer muscle of C. angulatus exhibited two fiber types: one with relatively fast-contracting fibers (shorter sarcomeres, myofilaments with an ordered arrangement, lineal Z discs, a well-developed sarcotubular system) and fatigue-resistant (numerous large mitochondria); and the other type, with slower-contracting fibers (longer sarcomeres, less orderly arranged myofilaments, wavy Z discs, a less developed sarcotubular system) and less resistant to fatigue (lower mitochondrial density). N. granulata showed only the slow, less resistant to fatigue type. The fibers less resistant to fatigue and more slowly contracting would presumably be used primarily for displays and agonistic interactions, whereas fast fibers with abundant mitochondria would be associated with continuous movements during feeding and grooming.

Preliminary Study of the Sonic Muscle of Micropogonias furnieri (Actinopterygii, Sciaenidae): Morfología e Histoquímica / Morphology and Histochemistry / Estudio Preliminar del Músculo del Sonido de Micropogonias furnieri (Actinopterygii, Sciaenidae)

The present study highlights the morphology of the Micropogonias furnieri sonic muscle by means of histochemical techniques, relating it to previous histochemical studies of the pectoral fin and myotomal muscles. In order to classify the muscle fibres, succinic dehydrogenase (SDH) for mitochondria, periodic acid Schiff (PAS) for glycogen, Sudan Black and Red for lipids and myosin adenosine triphosphatase (m-ATPase) pre-incubated at alkaline and acid pHs to visualize the contraction velocity, were used. The sonic fibres were smaller than the white myotomal and pectoral fibres, showed homogenous size and distribution and had features common to white fibres: negative to SDH and lipids, weakly positive to PAS and m-ATPase following acid pre-incubation, and positive to m-ATPase at alkaline pre-incubation. The morphology of the sonic muscle of M. furnieri showed no differences between sexes, probably due to the fact that the individuals were at the post spawning maturity stage. This similarity would indicate a similar sound production in both sexes, related to the "disturbance calls" of this species.

El presente trabajo estudia la morfología del músculo del sonido de Micropogonias furnieri por medio de técnicas histoquímicas y lo compara con trabajos previos de la histoquímica del músculo pectoral y miotomal. Con el fin de clasificar las fibras musculares se utilizaron distintas técnicas: succinato deshidrogenasa (SDH) para mitocondrias, ácido periódico Schiff (PAS) para evidenciar glucógeno, Sudan Black y Red para lípidos y miosin adenosina trifosfatasa (m-ATPasa) preincubada a pH alcalinos y ácidos para determinar la velocidad de contracción muscular. Las fibras del músculo del sonido son más pequeñas que las fibras blancas del músculo miotomal y pectoral, presentan un tamaño y distribución homogéneos, y tienen características histoquímicas de fibras blancas: son negativas para SDH y lípidos, débilmente positivas al PAS y a la técnica de m-ATPasa luego de preincubación ácida, y positivas a esta última técnica luego de preincubaciones alcalinas. La morfología del músculo del sonido de M. furnieri no mostró diferencias entre sexos, probablemente debido a que los individuos utilizados se encontraban en el estadio de post-desove. Esta similitud estaría relacionada con el tipo de sonido de "disturbio" que es emitido tanto por machos como por hembras durante todo el año.

Glycoconjugates in the mucosa of the digestive tract of Cynoscion guatucupa: a histochemical study.

This study addresses the histomorphology, the histochemistry and the distribution of glycoconjugates (GCs) in the mucosa of the digestive tract of the weakfish Cynoscion guatucupa. The histological characterization of the buccopharyngeal cavity and the esophagus revealed that they are lined by a stratified epithelium where the mucosa is thrown into longitudinal folds. The stomach is lined with a simple columnar secretory epithelium with tubular glands. GCs were analyzed using a range of histochemical methods. They were identified as oxidizable vicinal diols; sialic acids and some of their chain variants, C7, C8 or C9; sialic acid residues with O-acyl substitution at C8 or C9; carboxyl groups and sulfate groups. Sugar residues in the oligosaccharide side chains of the GCs were investigated using seven biotinylated lectins. Mucous cells from the contents of the buccopharyngeal cavity, esophagus and stomach evidenced neutral, sulphated and sialylated GCs. The latter were substituted mainly in C8. A moderately strong lectin labeling was observed in mucous cells of the three organs studied. Nonetheless, the apical edge of the gastric gland cells showed a strong positive labeling. The presence of different classes of GCs has been associated with different functions, such as lubrication, protection, inhibition of microorganisms proliferation and ionic regulation.