Fat necrosis with an associated lymphocytic infiltrate represents a histopathologic clue that distinguishes cellular dermatofibroma from dermatofibrosarcoma protuberans.

BACKGROUND: Cellular dermatofibromas (CDFs) and dermatofibrosarcoma protuberans (DFSP) can be challenging to differentiate from one another. Morphologically, both entities commonly extend into the subcutis, exhibit high cellularity with limited cytologic atypia and have a mixed fascicular-to-storiform growth pattern. We sought to evaluate the significance of fat necrosis with an associated lymphocytic infiltrate as a histopathologic clue for distinguishing CDFs from DFSP. METHODS: We identified cases in our pathology database with a primary diagnosis of CDF or DFSP. Punch or excisional biopsy specimens with extension into the subcutis were selected. Previously biopsied lesions and specimens that did not interact with the subcutis were excluded. Histopathologic features were evaluated in hematoxylin and eosin stained sections. RESULTS: Fat necrosis with lymphocytic infiltrate was present in 20/20 cases of CDF. None of the 20 DFSP cases had fat necrosis with lymphocytic infiltrate although 4/20 had fat necrosis alone. CONCLUSIONS: Fat necrosis with associated lymphocytic response can aid in the distinction between CDF and DFSP.

Morphometry and comparative histology of sinus and atrioventricular nodes in humans and pigs and their relevance in the prevention of nodal arrhythmias.

The cardiac conduction system is a network structure that allows the initiation and fast propagation of electrical impulses that trigger the electrical depolarization of the myocardial tissue. The purpose of this work is to study the histological and morphometric characteristics of the different components of the sinus and atrioventricular nodes in humans and pigs and their relationship with supraventricular arrhythmias. In this study, we describe the morphometry of the sinus and atrioventricular nodes of 10 adult humans and 10 pig hearts. A computerized morphometric study has been carried out, where we determined the number of cells that compose the nodes as well as different parameters related to their shape and size. The sinus node in human and pig is a compact structure, whose shape is oblong. Their cells (nodal and transitional cells) are pale and located in the center and the periphery, respectively. The atrioventricular node has also a shape oblong. P cells are pale in both species, but in humans, they are smaller than cardiomyocytes. The T cells are small and pale in both species, identified by hematoxylin-eosin and desmin stains. We have observed through a morphometric profile that the structure of sinus and atrioventricular nodes of pigs and humans show few differences. Pigs can be used as models for hemodynamic applications and experimental studies that include atrial electrical conduction and, in this way, prevent the presentation of arrhythmias that can generate sudden deaths in humans and pigs.

[Exploring the mysteries of megakaryocytopoiesis and thrombopoiesis through comparative hematology].

In modern hematology, research on hematopoiesis and blood cells in vertebrates, such as birds, reptiles, amphibians, and fish, is lagging. This is because there are many experimental constraints when selecting subjects other than humans and mice as research subjects. Currently, the availability of flow cytometry to count classified nucleated blood cells and utilization of whole genome information have led to novel findings. For example, in case of amphibian hematopoiesis studies, megakaryocytes have been found to be present in African clawed frogs (Xenopus laevis), which do not have platelets but have circulating nucleated thrombocytes. Moreover, we shed light on several mysteries, such as the C-terminal region in human TPO molecules not being found in birds, amphibians, and fish TPO molecules and the functional universalities of mutant CALR-MPL binding and EPO-EphB4 binding, in conjunction with comparative hematology.

Histopathological Analysis of 173 Consecutive Patients with Colorectal Carcinoma: A Pathologist's View.

BACKGROUND Worldwide, colorectal carcinomas are the third most common carcinomas in men and the second most common carcinomas in women. Pathological examination of rectum specimens requires special attention for correctly evaluating many prognostically important factors. In this study, we present pathological results of 173 lower anterior resection (LAR) and abdominoperineal resection (APR) specimens retrospectively evaluated. MATERIAL AND METHODS We included 173 LAR and APR specimens in this study. Patients were evaluated in the Istanbul Ekin Private Pathology Laboratory and underwent surgery at Çanakkale State Hospital, General Surgery Clinic. RESULTS Of the 173 specimens, 15 (8.7%) were APR and 158 (91.3%) were LAR specimens. Ninety-four patients (54.3%) were males and 79 patients (45.7%) were females. The mean age of the patients was 63.5 years (range 26-90 years). In the histopathological examination, malignant neoplasm was detected in 172 of the cases (99.4%) and benign endometriosis was detected in 1 of the cases (0.6%). There were 151 (87.2%), 8 (4.6%), 5 (2.9%), 1 (0.6%), 1 (0.6%), 1 (0.6%), 1 (0.6%), 1 (0.6%), and 4 (2.3%) patients with adenocarcinoma, mucinous adenocarcinoma, intramucosal adenocarcinoma in the setting of a high-grade tubulovillous adenoma, synchronous colon/prostate adenocarcinoma, malignant melanoma, signet ring cell carcinoma, gastrointestinal stromal tumor, endometriosis, and adenocarcinoma diagnosed by the examination of colonoscopic biopsy specimens that showed complete regression with neoadjuvant therapy, respectively. CONCLUSIONS When evaluating specimens from patients with colorectal carcinoma, pathological evaluation, which is one of the most fundamental pillars in managing patients with cancer, must be performed carefully and meticulously. Each pathological parameter should be evaluated carefully and clinicians and pathologists should evaluate these cases together.

Comparative histology of some craniofacial sutures and skull-base synchondroses in non-avian dinosaurs and their extant phylogenetic bracket.

Sutures and synchondroses, the fibrous and cartilaginous articulations found in the skulls of vertebrates, have been studied for many biological applications at the morphological scale. However, little is known about these articulations at the microscopic scale in non-mammalian vertebrates, including extant archosaurs (birds and crocodilians). The major goals of this paper were to: (i) document the microstructure of some sutures and synchondroses through ontogeny in archosaurs; (ii) compare these microstructures with previously published sutural histology (i.e. that of mammals); and (iii) document how these articulations with different morphological degrees of closure (open or obliterated) appear histologically. This was performed with histological analyses of skulls of emus, American alligators, a fossil crocodilian and ornithischian dinosaurs (hadrosaurids, pachycephalosaurids and ceratopsids). Emus and mammals possess a sutural periosteum until sutural fusion, but it disappears rapidly during ontogeny in American alligators. This study identified seven types of sutural mineralized tissues in extant and extinct archosaurs and grouped them into four categories: periosteal tissues; acellular tissues; fibrous tissues; and intratendinous tissues. Due to the presence of a periosteum in their sutures, emus and mammals possess periosteal tissues at their sutural borders. The mineralized sutural tissues of crocodilians and ornithischian dinosaurs are more variable and can also develop via a form of necrosis for acellular tissues and metaplasia for fibrous and intratendinous tissues. It was hypothesized that non-avian dinosaurs, like the American alligator, lacked a sutural periosteum and that their primary mode of ossification involved the direct mineralization of craniofacial sutures (instead of intramembranous ossification found in mammals and birds). However, we keep in mind that a bird-like sutural microstructure might have arisen within non-avian saurichians. While synchondroseal histology is relatively similar in archosaurs and mammals, the microstructural differences between the sutures of these two clades are undeniable. Moreover, the current results suggest that the degree of sutural closure can only accurately be known via microstructural analyses. This study sheds light on the microstructure and growth of archosaurian sutures and synchondroses, and reveals a unique, undocumented histological diversity in non-avian dinosaur skulls.

Of mice and women: a comparative tissue biology perspective of breast stem cells and differentiation.

Tissue based research requires a background in human and veterinary pathology, developmental biology, anatomy, as well as molecular and cellular biology. This type of comparative tissue biology (CTB) expertise is necessary to tackle some of the conceptual challenges in human breast stem cell research. It is our opinion that the scarcity of CTB expertise contributed to some erroneous interpretations in tissue based research, some of which are reviewed here in the context of breast stem cells. In this article we examine the dissimilarities between mouse and human mammary tissue and suggest how these may impact stem cell studies. In addition, we consider the differences between breast ducts vs. lobules and clarify how these affect the interpretation of results in stem cell research. Lastly, we introduce a new elaboration of normal epithelial cell types in human breast and discuss how this provides a clinically useful basis for breast cancer classification.

Intramandibular glands in different castes of leaf-cutting ant, Atta laevigata (Fr. Smith, 1858) (Formicidae: Attini).

Intramandibular glands have been poorly studied in polymorphic ants, where the differences between castes were unsufficiently scrutinized. Leaf-cutting ants possess one of the most complex systems of communication and labor division, which is polymorphic well as age polyethism, and makes them an ideal model for the study of intramandibular glands. This study has investigated the occurrence of intramandibular glands in female castes and subcastes of Atta laevigata. The mandibles of the queen, medium, and minor workers, and soldiers were submitted to histological, histochemical, ultrastructural, and morphometric analyses. The class-3 gland cells and the epidermal gland with a reservoir were found in all the castes. The queens and soldiers showed a higher number of class-3 gland cells, distributed within the mandible as well as a greater gland size in comparison to the workers. The histochemical tests, periodic acid-Schiff (PAS), mercury-bromophenol, and Nile blue, were similar for the class-3 gland cells and epidermal glands with a reservoir. However, the tests evidenced differences between the castes, with carbohydrates strongly positive in all of them, whereas neutral lipids were found in the queen and soldiers. The protein was weakly positive in the queen, whereas in the soldier, medium, and minor workers these reactions were strongly positive in the intramandibular glands. Our findings in A. laevigata suggest that intramandibular glands are directly involved in labor division and consequently in chemical communication between the castes.

Study on comparative histology of retinas in Ctenopharyngodon idella, Cynops orientalis, Bufo bufo gargarizans, Gekko japonicus, and Columba livia / Estudio histológico comparado de la retina en Ctenopharyngodon idella, Cynops orientalis, Bufo bufo gargarizans, Gekko japonicus, y Columba livia

The objective of this study was to explore the relationship between the retinal structure and its life adaptation to the environment of Ctenopharyngodon idella, Cynops orientalis, Bufo bufo gargarizans, Gekko japonicus and Columba livia . Measuring retinal thickness of each layer, the nuclei layer, and the diameter of each nuclear layer of the five animals, the statistical data analysis shows that: the nuclei layers of five animals are all 4, and their structures can be divided to 10 layers when observing with optical microscope. The retinal thickness of Ctenopharyngodon idella was 190.49 mm, Cynops orientalis was 173.07 µm, and the Bufo bufo gargarizans was 195.06 µm, Gekko japonicus was 224.32 µm and Columba livia was 174.10 µm. The number of retinal inner nuclear layers of Bufo bufo gargarizans and Gekko japonicus and Columba livia are more than their outer nuclear layers, on the contrary, retinal inner nuclear layers of Ctenopharyngodon idella and Cynops orientalis are less than their outer nuclear layers. The rod and cone layer of retina of Cynops orientalis were more advanced, but their nerve fiber layer (NFL) degraded highly, revealing a strong photosensitivity but a low visual sensitivity; to Columba livia , their NFL of retina are highly developed, so as their vision. The different structures and functions of the retina of Ctenopharyngodon idella, Cynops orientalis, Bufo bufo gargarizans, Gekko japonicus and Columba livia correspond with their behavioral characteristics and the living environment's change from aquatic to amphibious to land.

El objetivo de este estudio fue explorar la relación entre las estructuras de la retina y su adaptación al medioambiente en Ctenopharyngodon idella, Cynops orientalis, Bufo bufo gargarizans,Gekko japonicus y Columba livia . La medición del espesor de cada capa de la retina, la capa nuclear y su diámetro en los cinco animales, mostró a través del análisis estadístico que las capas nucleares en todos ellos fueron 4, y sus estructuras se pueden dividir en 10 capas cuando se observan con el microscopio óptico. El espesor de la retina de Ctenopharyngodon idella fue 190,49 µm, de Cynops orientalis fue 173,07 µm, de Bufo bufo gargarizans fue 195,06 µm, de Gekko japonicus fue 224,32 µm y de Columba livia fue 174,10 µm. El número de capas nucleares internas de la retina de Bufo gargarizans, Gekko japonicus y Columba livia fue mayor que sus capas nucleares externas, mientras que las capas nucleares internas de Ctenopharyngodon idella y Cynops orientalis fueron menos que las capas nucleares externas. La capa de conos y bastones de la retina de Cynops orientalis fue más desarrollada, pero su capa de fibras nerviosas presentó una elevada degeneración, lo que muestra una gran fotosensibilidad, pero una sensibilidad visual baja. En Columba livia, la capa de fibras nerviosas de la retina estuvo muy desarrollada, y de esta manera, su visión. El grado de desarrollo de las diferentes estructuras y funciones de la retina de Ctenopharyngodon idella, Cynops orientalis, Bufo bufo gargarizans, Gekko japonicus y Columba livia está relacionada con sus características de comportamiento y el cambio de las condiciones de las vidas acuática y anfibia en la tierra.

DICOM-based intravascular ultrasound signal intensity analysis: an Echoplaque Medical Imaging Bench study.

BACKGROUND: Most intravascular ultrasound (IVUS) data are stored digitally using the Digital Imaging and Communications in Medicine (DICOM) standard. This allows random access to studies and improves on the major limitation of conventional grayscale IVUS. METHODS: We harvested 129 coronary arteries from 43 autopsied cases. Grayscale IVUS and virtual histology-IVUS imaging were performed beginning 30 mm distal to the ostium of each coronary artery. Grayscale IVUS was processed; and the signal intensity was determined from DICOM-stored images using a new Medical Imaging Bench system (Echoplaque-MIB). We compared 436 regions of interest. The accuracy rate was expressed using the interpolation method and 95% confidence interval (CI). RESULTS: Patients' mean age was 49±9 years and 82% were men. Four patients succumbed to sudden cardiac death and 39 to noncardiac death. Grayscale IVUS signal intensity of dense calcium was 215±21.1 (95% CI: 207-223), that of fibrotic plaque was 75±17.8 (95% CI: 72-79), and that of fibrofatty plaque was 55±11.3 (95% CI: 52-59); however, the signal intensity of the necrotic core was between fibrotic plaque and dense calcium of 161±27.4 (95% CI: 153-168). Using the interpolation method, the cutoff values were as follows: fibrofatty plaque 0-65, fibrotic plaque 66-105, necrotic core 106-187, and dense calcium of at least 188. Overall, MIB grayscale had a 78.1% sensitivity and a 91.9% specificity versus histopathology. CONCLUSION: Plaque characterization using DICOM-based grayscale IVUS signal intensity analysis may improve on the major limitation of conventional grayscale IVUS: its inability to assess plaque composition.

An official American thoracic society workshop report: comparative pathobiology of fibrosing lung disorders in humans and domestic animals.

BACKGROUND: The clinical outcome of idiopathic pulmonary fibrosis (IPF) is poor, with a 50% survival rate at 3 years. Furthermore, current treatments provide little amelioration of symptoms. Despite significant advances in understanding the clinical features and pathobiology of IPF, further advances have been hampered by a lack of suitable animal models of the disease. Interestingly, spontaneously occurring disorders with a similarity to IPF have been recognized in the dog, cat, horse, and donkey. These disorders share clinical and pathologic features with human IPF and are emerging diseases of veterinary importance. PURPOSE: To improve awareness about these disorders in domestic animals and stimulate interactions between disciplines, and to facilitate the elucidation of mechanisms of fibrosing lung disorders using a comparative natural-occurrence disease model approach. METHODS: A 1-day meeting joined physicians, veterinarians, pathologists, researchers, and advocacy experts to discuss information available in this area. A review of the literature was conducted, and an executive committee discussed the findings and prepared a summary statement during subsequent meetings. RESULTS: Clinical, diagnostic, and treatment opportunities were identified, and common areas of interest where collaborative efforts could accelerate discovery regarding etiological factors, methods for early detection, determinants of disease progression, and novel therapies were defined. CONCLUSIONS: Comparing fibrosing lung disorders in humans and domestic animals will allow for a better understanding of the similarities and differences among species and may offer novel insights into the underlying mechanisms of spontaneously occurring fibrotic lung diseases.

[Comparative histology of mushroom bodies in carnivorous beetles of the suborder polyphaga (Insecta, Coleoptera)].

Mushroom bodies in beetles of the families Histeridae, Staphylinidae, Cantharidae, Trogossitidae, Peltidae, Cleridae, Malachiidae, and Coccinellidae are shown to be rather poorly developed. The calyx region of the mushroom bodies in these beetles never forms two separate cups, and the peduncular apparatus includes a unified shaft almost over its entire length. Only the pedunculus contains two separate shafts in a few cases. Two proliferative centers consisting of one to three neuroblasts are often found in each Kenyon cell group. The shift from carnivorous to feeding on pollen or leaves, which has taken place in some taxa, does not visibly affect the degree of mushroom body development.

Age-related changes in the central nervous system in selected domestic mammals and primates.

Aging is a process which operates at many levels of physiological, genetic and molecular organization and leads inevitably to death. Brain macroscopic changes by MRI investigation during aging were observed in humans and dogs but chimpanzees did not display significant changes. This suggestion led to the statement that brain aging is different in various species. Although human brain changes, e.g. ß-amyloid storage, neurofibrillary tangle formation, lipofuscin, are relatively well known, we are still looking for a suitable animal model to study the mechanisms of aging and neurodegenerative diseases. Therefore, this paper presents a comparative analysis of the changes described in the brains of senile dog, horse and gorilla. In addition we present the latest, non-invasive methods that can be applied in the diagnosis of old age in mammals. Our considerations have shown that the best animal model for further studies and observations on aging is the dog.

O gel de plasma rico em plaquetas propicia a regeneração da cartilagem articular do joelho de ovelhas / Platelet-rich plasma gel promotes regeneration of articular cartilage in knees of sheeps

Objetivo: Avaliar a regeneração da cartilagem articular em defeitos osteocondrais do joelho induzidos pelo plasma rico em plaquetas (PRP) autógeno. Métodos: Defeitos osteocondrais produzidos no sulco troclear de ambos os joelhos de dez ovelhas foram preenchidos com PRP autógeno à direita e deixados vazios à esquerda. Avaliação macroscópica e histológica foram efetuadas 12 semanas mais tarde. Os resultados foram avaliados por um escore geral de ambas as avaliações macroscópica e histológica comparativamente entre os lados por meio do teste pareado de Wilcoxon. Resultados: o aspecto macroscópico não foi uniforme entre os animais, nem diferiu entre os joelhos direitos e esquerdos (p=0,03125); em nenhum caso o tecido regenerado se nivelou com a cartilagem normal circundante. Ao exame histológico, cartilagem aparentemente normal não foi detectada em nenhum joelho, mas uma cartilagem pouco diferenciada estava presente em sete joelhos direitos e em três joelhos esquerdos. Tecido fibrocartilaginoso estava presente nos joelhos restantes, com diferença significante no escore geral entre os joelhos direitos e esquerdos (p=0,0313). Conclusão: o PRP como usado neste estudo tem propriedades reparativas da cartilagem articular no joelho de ovelhas, principalmente por estimular a formação de tecido fibrocartilaginoso. Trabalho Experimental.

Objective: To assess the regeneration of osteochondral defects in the joint cartilage of the knee induced by autologous platelet-rich plasma (PRP). methods: osteochondral defects produced in the trochlear groove of both knees of ten sheep; defects of the right knees were filled with autologous PRP and the left knees were left unfilled. macroscopic and microscopic evaluation was carried out 12 week later. the results were evaluated by the total score of both macroscopic and microscopic evaluations comparing the two sides through the wilcoxon paired test. Results: macroscopic appearance was not uniform among animals, nor was it different between the right and left knees (p=0.3125), and in no case the regenerated tissue was equal to the normal surrounding cartilage. At histological examination, apparently normal cartilage was not detected in any knee, but a poorly differentiated cartilage was present in 7 right knees, compared to 3 left knees. Fibrocartilaginous tissue was present in most of the remaining knees, with a significant difference in the overall score between right and left knees (p=0.0313). conclusion: the pRp as used in this study has reparative properties of the joint cartilage of sheep knees, mostly by stimulating the formation of a fibrocartilaginous tissue. Laboratory Investigation.

Carcinogênese mamária experimental induzida pelo 7, 12, dimetilbenz (A) antraceno (DMBA): caracterização histopatológica comparada e identificação imunoistoquímica de células-tronco neoplásicas (CTNs) / Breast cancer neoplastic stem cells histology compared Sprague Dawley rats 7, 12 dimetilbenz (A) antracene

O câncer de mama é a neoplasia maligna mais prevalente e a principal causa de óbito entre mulheres, no mundo. A despeito de avanços substanciais no entendimento da biologia da doença, nos métodos de detecção precoce, e em sua farmacoterapia, a sobrevida geral não se modificou significantemente nas últimas décadas. Portanto, pode se dizer que um dos deveres primordiais das Universidades Públicas engajadas com pesquisa básica e aplicadas consiste em contribuir para o desenvolvimento de novas estratégias de tratamento sistêmico desta neoplasia. Nesse contexto, um dos alvos estratégicos mais promissores no desenvolvimento de novos fármacos antineoplásicos é representado pela célula-tronco neoplásica (CTN). As CTNs têm sido associadas em inúmeros estudos à capacidade de algumas neoplasias malignas de resistir às principais modalidades terapêuticas antineoplásicas, especialmente à: radio-, quimio-, hormônio- e imunoterapias. Em resumo, na atualidade, a detecção de CTNs constitui uma ferramenta clínica bastante promissora enquanto alvo terapêutico, fator prognóstico e preditivo de resposta terapêutica. O objetivo deste trabalho foi descrever e discutir as potencialidades e limitações do modelo de carcinogênese mamária pelo DMBA, após reclassificação das neoplasias mamárias segundo os critérios diagnósticos da OMS (2003, 2012), subtipagem molecular e quantificação de imunomarcadores prognósticos, preditivos e de CTN. Após a aplicação do protocolo experimental de indução química pelo DMBA e a eutanásia dos animais controle e experimental, suas linhas mamárias (contendo ou não tumores) foram ressecadas e avaliadas quanto à morfologia e a imunoexpressão para marcadores de CTNs. Após 13 semanas, 100% dos animais desenvolveram neoplasias macroscópicas e histologicamente compatíveis com os critérios de avaliação indicados pela OMS.

Breast cancer is the most common malignancy and the leading cause of death from cancer among females worldwide. Despite all the research and all the progress, methods of early detection, and its pharmacotherapy, overall survival has not changed significantly in recent decades. Therefore, the Public University has been engaged in basic and applied research is too contributed to the development of new strategies for systemic treatment of this malignancy. In this context, one of the most promising strategic targets in the development of the anticancer drugs is represented by neoplastic stem cell (NSC). Neoplastic stem cell has been linked in various studies to the capacity of some malignancies to resist major antineoplastic therapeutic modalities, especially: radio-, chemo-, hormone- and immunotherapies. In summary, the detection of NSCs is a clinical tool very promising while therapeutic target and prognostic factor predictive of therapeutic response. The aim of this study was to describe and discuss the strengths and limitations of the model of mammary carcinogenesis by DMBA, after reclassification of breast cancer according to the diagnostic criteria of the WHO (2003, 2012), and quantification of molecular subtyping prognostic immunomarkers, predictive and NSC. After application of the experimental protocol of chemical induction by DMBA and euthanasia of experimental and control animals, the mammary lines (with or without tumors) were resected and evaluated the morphology and immunostaining for markers of NSCs. After 13 weeks, 100% of the animals developed macroscopic neoplasms and histologically consistent with the evaluation criteria of evaluation indicated by WHO. Tumors were classified as ductal carcinoma, papillary carcinoma, lobular carcinoma, myoepithelial carcinoma and phyllodes tumor, being the most common type, the ductal. Few immunohistochemical markers correlated with variable behavior biological.

Placenta: Anatomía e Histología Comparada / Placenta: Compared Anatomy and Histology

La placenta, anexo embrionario propio de los mamíferos placentados, imprescindible para la supervivencia embriofetal, está formada por la zona más superficial del endometrio y el corion, asociado con el saco vitelino o el alantoides, dependiendo de la especie. La placenta provee el intercambio gaseoso y nutricio entre la madre y el feto, secreta hormonas y posee propiedades inmunosupresoras. Existen diferentes criterios para clasificar la placenta; de acuerdo a la distribución de las vellosidades coriales de la placenta: difusa, cotiledonaria, zonaria y discoidal; de acuerdo a las características histológicas de la placenta: epiteliocorial, sindesmocorial, endoteliocorial y hemocorial.

The placenta is an extraembryonic membrane of placental mammals, essential for embryo survival. It is formed by the most superficial zone of the endometrium and the chorion, associated with the yolk sac or allantois, depending on the species. The placenta provides gas and nutrient exchange between mother and fetus, secretes hormones and has immunosuppressive properties. There are different criteria to classify the placenta; i. e. according to the distribution of the chorionic villi of the placenta: diffuse, cotyledonary, zonaria and discoidal; according to the histological characteristics of the placenta: epitheliochorial, syndesmochorial, endotheliochorial and hemocorial.

Franz von Leydig (1821-1908), pioneer of comparative histology.

Franz von Leydig, a German histologist and zoologist, is known to every student of human or animal anatomy because of the testicular testosterone-producing cells carrying his name. However, he made many contributions to our knowledge of the fine structure of animal tissues, including more than 200 scientific articles and several books. His most important work, the book Lehrbuch der Histologie des Menschen und der Thiere, established him as a pioneer if not the founder of comparative histology. Leydig taught at three different universities (Würzburg, Tübingen and Bonn) and received many honours from scientific organizations worldwide, including the Royal Society. He died in Rothenburg ob der Tauber, the town of his birth, aged 86 years.

The utility of osteon shape and circularity for differentiating human and non-human Haversian bone.

Distinguishing human from non-human bone fragments is usually accomplished by observation of gross morphology. When macroscopic analysis is insufficient, histological approaches can be applied. Microscopic features, like plexiform bone or osteon banding, are characteristic of non-humans. In the absence of such features, distinguishing Haversian bone as either human or non-human proves problematic. This study proposes a histomorphometric approach for classifying species from Haversian bone. Two variables, osteon area (On.Ar.) and circularity (On.Cr.), are examined. Measurements were collected from three species (deer, dog, human) represented by various skeletal elements; only ribs were available for humans (ribs: deer n = 6, dog n = 6, human n = 26; humeri: deer n = 6, dog n = 6; femora: deer n = 6, dog n = 6). Qualitative analysis comparing human to non-human On.Ar. demonstrated that human ribs have larger mean On.Ar. (0.036 mm(2)) than non-human ribs (deer = 0.017 mm(2) , dog = 0.013 mm(2)). On.Cr. in the ribs showed minor differences between species (deer = 0.877; dog = 0.885; human = 0.898). Results demonstrated no significant difference across long bone quadrants in long bones. Discriminant analyses run on the means for each sample demonstrated overlap in deer and dog samples, clustering the non-human and human groups apart from each other. Mean On.Cr. proved a poor criterion (ribs only: 76.3%, pooled elements: 66.1%), while mean On.Ar. proved useful in identifying human from non-human samples (ribs only: 92.1%, pooled elements: 93.5%). When variables were combined, accuracy increased to 100% correct classification for rib data and 98.4% when considering data from all elements. These results indicate that On.Ar. and On.Cr. are valuable histomorphometric tools for distinguishing human from non-human Haversian bone.

Evaluation of the rabbit nasal cavity in inhalation studies and a comparison with other common laboratory species and man.

The rabbit is occasionally used for inhalation and intranasal safety assessment studies, but there are no detailed descriptions of the anatomy or histology of the rabbit nose. To address this deficit, the nasal cavities of thirty-two control adult rabbits were sectioned and examined to provide mapping of the main epithelial types and histological structures present within the cavity and turbinates. Four levels of the nasal cavity were prepared and examined using anatomic landmarks. Level I was sectioned immediately posterior to the incisors, Level II at the first palatal ridge, Level III immediately anterior to the first upper premolar teeth, and Level IV immediately anterior to the first upper molar. Level I was lined predominantly by squamous epithelium with small amounts of thick transitional epithelium, and examination is recommended only for studies involving test article administration via instillation. Level II was lined primarily with transitional and respiratory epithelia, whereas Levels III and IV were lined with respiratory and olfactory epithelia and often contained nasal-associated lymphoid tissue. The vomeronasal organs were evident only in Level II. The similarities and differences of these features are compared with those of other common laboratory species (rat, mouse, dog, and cynomolgus monkey) and man.