Comparative postcranial osteohistology and bone histovariability of aquatic and terrestrial turtles: the case of the South American Phrynops hilarii, Hydromedusa tectifera (Pleurodira, Chelidae), and Chelonoidis chilensis (Cryptodira, Testudinidae).

This article presents a detailed comparative analysis of the bone microstructure of three extant species of South American turtles. The main histological characteristics of postcranial bones are identified, as well as the intraskeletal, ontogenetic and interspecific variation between aquatic and terrestrial species. For this purpose, thin sections of postcranial bones (seventh cervical vertebra, coracoid, scapula, humerus, radius, ulna, ischium, ilium, pubis, femur, tibia, and fibula) of juvenile and adult specimens of aquatic (Phrynops hilarii and Hydromedusa tectifera) and terrestrial (Chelonoidis chilensis) turtles were analyzed. Bone histology revealed an intraskeletal variation of the microanatomical and microstructural organization in these turtles. The cortical bone is composed of poorly vascularized lamellar and parallel-fibered bone tissue interrupted with lines of arrested growth (LAGs), reflecting a cyclical slow growth rate throughout these turtles' life. Although in the adult specimens a growth rate decrease was observed, none of them have reached somatic maturity. The juvenile and the adult of Chelonoidis chilensis, unlike the aquatic species studied, presented a higher vascularization in their bones, which could imply a faster growth rate in this land specie. The number of LAGs was higher in the stylopodial and zeugopodial bones, which would make these elements suitable for approximate age estimations. Pectoral and pelvic girdle bones also exhibited a good record of LAGs. The information here obtained on extant species represents a powerful tool for the interpretation of paleobiological traits present in closely related fossil forms.

Avoiding vascular complications in insular glioma surgery - A microsurgical anatomy study and critical reflections regarding intraoperative findings.

Introduction: Vascular lesions in insular glioma surgery can severely impact patients' quality of life. This study aims to present the results of our dissections and authors' reflections on the insular vascular anatomy. Matherials and Methods: The insular vascularization was examined using ×3 to ×40 magnification in 20 cadaveric cerebral hemispheres in which the arteries and veins had been perfused with colored silicone. Results: In insular gliomas, this individualization of the anatomical structures is rarely possible, as the gyri are swollen by the tumor and lose their individuality. In the transsylvian approaches, the anatomical parameters for delimiting the insula in tumors are best provided by the superior and inferior circular sulci. The branches of the MCA are easily identified in the transcortical approach, but only at the end of the surgery after the tumor is resected.). One of the factors under-discussed in the literature is the involvement of the lenticulostriate arteries by the medial part of the tumor. In our experience of 52 patients (article submitted to publishing), LSTa were founded to be involved by the tumor in 13 cases. In 39 patients, there was no involvement of the LSTa, which allowed a more aggressive resection. Early preoperative identification of the anterior perforated substance on the MRI and its proximity to the tumor may help determine the route of the LSTa over the medial tumor boundaries. Discussion: Our reflections introduced our imaging and anatomical concept regarding LSTa in insular glioma surgery. Accurate identification of origin, route, and distribution of the LSTa is pivotal to surgical success, especially in the lateral group. The anatomical knowledge of their path directly impacts the extent of tumor resection and functional preservation. Conclusion: Knowledge of microsurgical anatomy, brain mapping, and surgical experience counts a lot in this type of surgery, creating a reasonable procedure flowchart to be taken intraoperatively.

Histological verification of atherosclerosis due to bends and bifurcations in carotid arteries predicted by hemodynamic model.

BACKGROUND: Tortuosity and bifurcations in carotid arteries alter the blood flow, causing atherosclerosis. OBJECTIVES: The aim of the present study is to analyze the effect of variant vascular anatomy in the cervical region on development of atherosclerosis by microanatomical examination. METHODS: The effect of blood flow at anomalous bends and bifurcations was observed in right carotid arteries of a seventy year old female cadaver. Fifteen histological slides were prepared from the carotid arteries and interpreted to verify predictions of atherosclerosis. RESULTS: The model predicts atherosclerosis at bends, bifurcations and large aperture arteries. Microanatomical examination revealed presence of atherosclerosis of varying thickness at the bends and bifurcation in the right carotid arteries, as predicted. Atherosclerosis was also detected in the straight part of the wider common carotid artery. No atherosclerosis was observed in the contralateral carotid arteries. The variant carotid vascular anatomy consisting of bends, bifurcations and wider arteries revealed that the shear stress and velocity of blood flow are reduced at these anomalous sites. CONCLUSIONS: Anatomical anomalies such as bends and branching in the carotid arteries alter the irrigation pattern and generate biomechanical forces that cause turbulent flow and reduce shear stress/blood flow velocity. Decreased shear stress and velocity causes development of atherosclerosis. Histological slides established the presence of atherosclerosis at bends and bifurcations and in wider arteries.

CONTEXTO: Tortuosidade e bifurcações das artérias carótidas alteram o fluxo sanguíneo, causando aterosclerose. OBJETIVOS: O objetivo do presente estudo foi analisar o efeito de anatomia vascular variante na região cervical sobre o desenvolvimento de aterosclerose via exame microanatômico. MÉTODOS: O efeito do fluxo sanguíneo em dobras e bifurcações anômalas foi observado nas artérias carótidas do lado direito em um cadáver do sexo feminino de 70 anos de idade. Quinze lâminas histológicas foram preparadas a partir das artérias carótidas e interpretadas para confirmar as previsões de aterosclerose. RESULTADOS: O modelo prevê aterosclerose em dobras, bifurcações e artérias de grande calibre. O exame microanatômico revelou a presença de aterosclerose de densidades variáveis nas dobras e bifurcação das artérias carótidas do lado direito, conforme previsto. Aterosclerose também foi detectada na parte reta da artéria carótida comum mais larga. Não foi observada aterosclerose nas artérias carótidas contralaterais. A anatomia vascular carotídea variante consistindo de dobras, bifurcações e artérias mais largas revelou que a tensão de cisalhamento (shear stress) e a velocidade do fluxo sanguíneo são reduzidos nesses pontos anômalos. CONCLUSÕES: Anomalias anatômicas tais como dobras e ramificações das artérias carótidas alteram o padrão de irrigação e geram forças biomecânicas que causam fluxo turbulento e reduzem a tensão de cisalhamento e a velocidade do fluxo. Tensão e velocidade menores causam o desenvolvimento de aterosclerose. As lâminas histológicas estabeleceram a presença de aterosclerose nas dobras e bifurcações nas artérias mais largas.

Shell bone histology of the long-necked chelid Yaminuechelys (Testudines: Pleurodira) from the late Cretaceous-early Palaeocene of Patagonia with comments on the histogenesis of bone ornamentation.

Yaminuechelys is a long-necked chelid turtle whose remains have been recovered from outcrops of the Santonian-Maastrichtian and Danian of South America. With the purpose of providing data about shell sculpturing origin and palaeoecology, the bone histology of several shell elements (including neural, costal, peripheral and plastral plates) of Yaminuechelys is described herein. Histological analysis reveals that Yaminuechelys shares with Chelidae the presence of interwoven structural fibre bundles in the external cortex, and parallel-fibred bone of the internal cortex. The presence of resorption lines in several samples indicates that the particular ornamentation of the external surfaces originated, at least in part, by focalized resorption and new bone deposition. This mechanism for ornamentation origin and maintenance is here described for the first time in a turtle. Compactness of the shell bones is consistent with an aquatic habitat, which supports previous hypothesis based on palaeoenvironmental and morphological data.

A dendritic organization of lateral amygdala neurons in fear susceptible and resistant mice.

Subtle differences in neuronal microanatomy may be coded in individuals with genetic susceptibility for neuropsychiatric disorders. Genetic susceptibility is a significant risk factor in the development of anxiety disorders, including post-traumatic stress disorder (PTSD). Pavlovian fear conditioning has been proposed to model key aspects of PTSD. According to this theory, PTSD begins with the formation of a traumatic memory which connects relevant environmental stimuli to significant threats to life. The lateral amygdala (LA) is considered to be a key network hub for the establishment of Pavlovian fear conditioning. Substantial research has also linked the LA to PTSD. Here we used a genetic mouse model of fear susceptibility (F-S) and resistance (F-R) to investigate the dendritic and spine structure of principal neurons located in the LA. F-S and F-R lines were bi-directionally selected based on divergent levels of contextual and cued conditioned freezing in response to fear-evoking footshocks. We examined LA principal neuron dendritic and spine morphology in the offspring of experimentally naive F-S and F-R mice. We found differences in the spatial distribution of dendritic branch points across the length of the dendrite tree, with a significant increase in branch points at more distal locations in the F-S compared with F-R line. These results suggest a genetic predisposition toward differences in fear memory strength associated with a dendritic branch point organization of principal neurons in the LA. These micro-anatomical differences in neuron structure in a genetic mouse model of fear susceptibility and resistance provide important insights into the cellular mechanisms of pathophysiology underlying genetic predispositions to anxiety and PTSD.

Osteoderm histology of Proterochampsia and Doswelliidae (Reptilia: Archosauriformes) and their evolutionary and paleobiological implications.

Postcranial osteoderms are commonly developed in the major lineages of Archosauriformes, including forms such as proterochampsids and doswelliids. Here, we survey the histology of osteoderms of the doswelliids Archeopelta arborensis and Tarjadia ruthae, and the proterochampsids Chanaresuchus bonapartei and Pseudochampsa ischigualastensis to understand better the morphogenesis of these skeletal elements. Whereas, the Doswelliid osteoderms possess a trilaminar organization, in which two cortices (external and basal) can be differentiated from an internal core of cancellous bone, these elements are compact structures in proterochampsids. The osteoderms of P. ischigualastensis are avascular and they consist entirely of parallel-fibered bone. Conversely, the osteoderms of C. bonapartei are well vascularized structures composed of zones of woven-fibered bone and annuli of parallel-fibered bone. The rather simple microstructure observed in P. ischigualastensis osteoderms suggests that these elements grew at a constant, low rate. Compared with proterochampsids, doswelliid osteoderms possess a more complex histology, which appears to be linked to variations in the growth rate during the osteoderm formation and also to the development of the external ornamentation. A comparison of our findings with the results of earlier studies on other archosauriforms (phytosaurs and pseudosuchians) reveals that the general osteoderm histology of doswelliids bears a closer resemblance to that of phytosaurs and pseudosuchians than the proterochampsid osteoderm microstructure. If all archosauriform osteoderms are homologous structures, the closer resemblance of doswellid osteoderm microstructures to that of phytosaurs and pseudosuchians is in agreement with the hypothesis that doswellids are more closely related to archosaurs than proterochampsids. J. Morphol. 276:385-402, 2015. © 2015 Wiley Periodicals, Inc.

A new segment of the trochlear nerve: cadaveric study with application to skull base surgery.

Objectives The trochlear nerve is important to preserve during approaches to the skull base. Traditionally, this nerve has been divided into cisternal, cavernous, and orbital segments. However, the authors anecdotally observed an additional segment during routine cadaveric dissections. Therefore, they performed this study to better elucidate this anatomy. Design Twenty latex-injected cadaveric sides (10 adult cadavers) were dissected with the aid of an operating microscope. Standard microdissection techniques were used to examine the course of the distal cisternal and precavernous segments of the trochlear nerve. Setting Cadaver laboratory. Main Outcome Measures Measurements were made using a microcaliper. Digital images were made of the dissections. Results The authors identified a previously undescribed segment of the trochlear nerve in all specimens. This part of the nerve coursed between the entrance of the trochlear nerve into the posterior corner of the oculomotor trigone to the posterior wall of the cavernous sinus. This segment of trochlear nerve was, on average, 4 mm in length. Conclusions The authors have identified a new segment of the trochlear nerve not previously described. They propose that this be referred to as the trigonal segment. Knowledge of the microanatomy of the trochlear nerve is useful to skull base surgeons.

Morphologic evaluation of the fetal recurrent laryngeal nerve and motor units in the thyroarytenoid muscle.

This study is a morphologic description of the recurrent laryngeal nerve (RLN) and of the number and size of motor units (MUs) in the thyroarytenoid (TA) muscle bilaterally of a human fetus aged 25 weeks. A quantitative analysis of RLN and MUs is presented to investigate similarities with equivalent structures in adults. In the fetus used in our study, the morphologic organization of the RLN was similar to that commonly described in the adult RLN. Moreover, as is observed in adult TA, the TA of the analyzed fetus, particularly the right TA, showed MUs typical of muscles with great motor accuracy. These results may be used to increase our knowledge of the features of the voice in adults and newborns.

Morphology: histology and histochemistry of the venom apparatus of the centipede, Scolopendra valida (Chilopoda, Scolopendridae) / Morfología, histología e histoquímica del aparato venenoso del ciempiés: Scolopendra valida (Chilopoda, Scolopendridae)

Morphological, histological and histochemical characterizations of the venom apparatus of the centapede, S. valida have been investigated. The venom apparatus of Scolopendra valida consists of a pair of maxillipedes and venom glands situated anteriorly in the prosoma on either side of the first segment of the body. Each venom gland is continuous with a hollow tubular claw possessing a sharp tip and subterminal pore located on the outer curvature. The glandular epithelium is folded and consists of a mass of secretory epithelium, covered by a sheath of striated muscles. The secretory epithelium consists of high columnar venom-producing cells having dense cytoplasmic venom granules. The glandular canal lacks musculature and is lined with chitinous internal layer and simple cuboidal epithelium. The histochemical results indicate that the venom-producing cells of both glands elaborate glycosaminoglycan, acid mucosubstances, certain amino acids and proteins, but are devoid of glycogen. The structure and secretions of centipede venom glands are discussed within the context of the present results.

Fueron investigadas las características morfológicas, histológicas e histoquímicas del aparato venenoso del ciempiés, S. valida. El aparato venenoso de Scolopendra valida consta de un par de maxilopodos y glándulas de veneno situadas anteriormente en el prosoma, a cada lado del primer segmento del cuerpo. Cada glándula de veneno se continúa en una garra con una cavidad tubular que posee una punta afilada y un poro subterminal situado sobre la curvatura externa. El epitelio glandular es plegado y se compone de una masa de epitelio secretor, cubierto por una vaina de los músculos estriados. El epitelio secretor consiste en células columnares altas productoras de veneno con gránulos citoplasmáticos de veneno densos. El conducto glandular carece de musculatura y está revestido por capa interna quitinosa y epitelio cuboidal simple. Los resultados histoquímicos indican que las células productoras de veneno de ambas glándulas elaboran glucosaminoglucanos mucosustancias ácidas, ciertos aminoácidos y proteínas, pero carecen de glucógeno. La estructura y las secreciones de las glándulas de veneno del ciempiés son examinadas en el contexto de los presentes resultados.

A comparative histological study of the tongue of rat (Rattus norvegicus), bat (Eidolon helvum) and pangolin (Manis tricuspis) / Estudio histológico comparativo de la lengua de rata (Rattus norvegicus), murciélago (Eidolon helvum) y pangolín (Manis tricuspis)

This study assessed the micro anatomical differences in the tongue of rat, bat and pangolin with a view to establishing the functional anatomical differences of these mammalian tongues on their dietary pattern. Ten rats, ten bats and ten pangolins were used for this study. The animals were sacrificed and the tongue excised and processed for light microscopical study adopting the following stains: Haematoxylin Eosin, Verhoeff Gieson and Masson trichrome. The results showed non papillation of the keratinized stratified epithelium of pangolin tongue unlike the papillation seen in the tongue of the rat and bat. While the filiform papillation seen in the rat was bristle like, the filiform papillae in the bat were crown-like. There was also an unusual dense collagenous ring in the proximal portion of the pangolin tongue which was absent in other mammals. There were taste buds along the lateral walls of the vallate papillae in the distal portion of the tongue of rats and bats but none was found in the pangolins. In conclusion, the morphology of the tongues of these mammals showed a relationship between their feeding pattern and the adaptive changes in the microanatomy of their tongue.

Se evaluó los aspectos micro-anatómicos de la lengua de la rata, murciélago y pangolín, con miras a establecer las diferencias funcionales anatómicas de las lenguas de estos mamíferos en su patrón alimentario. Diez ejemplares de cada animal se utilizaron para este estudio. Los animales fueron sacrificados y las lenguas fueron extirpadas y procesadas para el estudio microscópico de luz, usándose las tinciones: Hematoxilina Eosina, Verhoeff Gieson y tricrómico de Masson. Los resultados mostraron la no papilación del epitelio estratificado queratinizado de la lengua de pangolines a diferencia de la papilación vista en la lengua de la rata y del murciélago. Por otro lado, las papilas filiformes vistas en la rata se presentaban como puntas, siendo como coronas en el murciélago. También hubo un inusual anillo de colágeno denso en la porción proximal de la lengua de pangolines, estando ausente en los otros mamíferos. Se observaron botones gustativos a lo largo de las paredes laterales de las papilas caliciformes en la porción distal de la lengua de las ratas y los murciélagos, pero ninguno fue encontrado en la de los pangolines. En conclusión, la morfología de las lenguas de estos mamíferos mostró una relación entre su patrón de alimentación y los cambios de adaptación en la anatomía microscópica de la lengua.

A comparative study of the ileum in rat (Rattus norvegicus), Bat (Eidolon helvum) and Pangolin (Manis tricuspis) as investigated using histological method / Estudio comparativo del íleon en rata (Rattus norvegicus), murciélago (Eidolon helvum) y pangolín (Manis tricuspis) utilizando como investigación el método histológico

The histological and morphometric differences in some parts of the gastrointestinal tracts of rat, bat and pangolin have been well established. This investigation aims at comparatively elucidating any adaptational changes the ileum of the three mammals must have adopted to meet its dietary requirements and also cope with their morphological differences. The investigation was carried out using ten rats, ten bats and ten pangolins of both sexes. The animals were slightly anaesthetized under chloroform inhalation. The intestines were harvested and the ileum excised and fixed in 10 percent formol saline. The tissues were processed for light microscopic study. The following stains were employed: Haematoxylin and eosin (H & E), Van Gieson and Verhoeff's haematoxylin elastic tissue stain. Stained slides were also analysed morphometrically. The results revealed microstructural modifications which characterized the mucosa as well as the pattern of distribution of the conjuntive tissue fibers in the ileum of the three mammals. These modifications are means of successfully coping with their respective diets and morphological differences.

Las diferencias histológicas y morfométricas en algunas partes del tubo digestivo de ratas, murciélagos y pangolines han sido bien establecidos. Esta investigación tiene por objeto aclarar comparativamente cualquier cambio de adaptación del íleon de los tres mamíferos que hayan adoptado para satisfacer sus necesidades dietéticas y también hacer frente a sus diferencias morfológicas. La investigación se llevó a cabo usando 10 ratas, 10 murciélagos y 10 pangolines, de ambos sexos. Los animales fueron ligeramente anestesiados bajo inhalación de cloroformo. Los intestinos fueron expuestos, el íleon extirpado y fijado en formol salino al 10 por ciento. Los tejidos fueron procesados para su estudio por microscopía de luz. Los siguientes tinciones fueron empleadas: Hematoxilina y eosina (H & E), Van Gieson y tinción de hematoxilina para tejidos elásticos de Verhoeff. Los cortes teñidos también se analizaron morfométricamente. Los resultados revelaron modificaciones microestructurales características de la mucosa, así como el patrón de distribución de las fibras de tejido conjuntivo en el íleon de los tres mamíferos. Estas modificaciones son el medio para entender sus diferencias en la dieta y morfología respectivamente.