Anatomical investigation of the measurements, shape and arterial irrigation of the adrenal gland in New Zealand rabbits / Investigação anatômica das medidas, forma e irrigação arterial da glândula adrenal em coelhos da raça Nova Zelândia

Rabbits have been used as an experimental model in many studies. These studies are important not only for veterinary clinicians, but also for researchers in different fields. The aim of this research was to describe gross morphological measurement, shape and arterial supply of the adrenal glands in healthy New Zealand rabbits. Dissections were performed in 30 adult rabbits, 15 males and 15 females, without macroscopic adrenal pathology. Adrenal measurements were made with a digital caliper: length, width, and thickness. The origin of the adrenal arteries was also determined. Both adrenal glands were localized cranially to the respective kidneys. The mean of the right adrenal gland was 0.88 cm length, 0.42 cm width and 0.16 cm thickness; the left gland measured 0.72 cm, 0.46 cm, and 0.17 cm, respectively. The right gland was significantly more elongated than the left (p = 0.0003) and the means of the measurements did not differ between sexes. Most of the right adrenal glands had a piriform shape (73.3%), whereas most of the left gland exhibited a "bean-shaped" aspect (60.0%). The arterial supply was found to arise from different arteries: lumbar, aorta, renal, caudal mesenteric, and testicular or ovarian. Comparatively, the descriptions of shape, position and arterial irrigation of the adrenal gland in rabbits are similar to those available in rodents. The data from the present investigation will assist in the interpretation of pathological and / or experimental findings in New Zealand rabbits.

Coelhos têm sido utilizados como modelo experimental em muitos estudos. Esses estudos são importantes não apenas para médicos veterinários, mas também para pesquisadores de diferentes campos. O objetivo desta pesquisa foi descrever as medidas morfológicas macroscópicas, forma e suprimento arterial das glândulas adrenais em coelhos saudáveis da raça Nova Zelândia. As dissecções foram realizadas em 30 coelhos adultos, 15 machos e 15 fêmeas, sem sinais macroscópicos de patologia adrenal. As medidas adrenais foram realizadas com paquímetro digital: comprimento, largura e espessura. A origem das artérias adrenais também foi determinada. Ambas as glândulas adrenais foram localizadas cranialmente nos respectivos rins. A média da glândula adrenal direita foi de 0,88 cm de comprimento, 0,42 cm de largura e 0,16 cm de espessura; a glândula esquerda mediu 0,72 cm, 0,46 cm e 0,17 cm, respectivamente. A glândula direita foi significativamente mais alongada que a esquerda (p = 0,0003) e as médias das medidas não diferiram entre os sexos. A maioria das glândulas adrenais direitas tinha uma forma piriforme (73,3%), enquanto a maioria da glândula esquerda exibia um aspecto em "forma de feijão" (60,0%). Verificou-se que o suprimento arterial provém de diferentes artérias: lombar, aorta, renal, mesentérica caudal e testicular ou ovariana. Comparativamente, as descrições de forma, posição e irrigação arterial da glândula adrenal em coelhos são semelhantes às disponíveis em roedores. Os dados da presente investigação ajudarão na interpretação de achados patológicos e / ou experimentais em coelhos da raça Nova Zelândia.

Apteryx spp (Kiwi) possess an uropygial gland: Anatomy and pathology

The uropygial gland is a prominent feature of the avian anatomy but there is limited information on its structure and function. The gland is of current interest because it provides a source for volatile chemicals that can be used by birds in communication. We examined the anatomy of uropygial glands in Apteryx for the first time. The gland was located immediately caudal to the cloaca and surrounding the coccygeal bone rather than rostral to the coccygeal bone and above the posterior free caudal vertebrae as in other birds. This may explain why it has not been recognised until relatively recently. Like most uropygial glands Apteryx’s were bilobar but possessed eight primary sinuses, each opening through its own orifice in the gland’s papilla. Primary ducts were compact and branches of connective tissue extending from the capsule internally formed interfollicular septae that were thicker in some areas, grouping follicles into discrete lobules. Striated muscle was present in the capsule, a characteristic so far unique to Apteryx that may be used in controlling the expulsion of secretion. There were significant differences in the architecture of the follicles between species and sexes that suggest differences in the production, storage and availability of uropygial gland secretion. This was supported by variations in live bird’s gland volume between two years of sampling. Atrophy of the uropygial gland was seen in two birds in poor condition suggesting that health impacts the functioning of the gland. This finding suggests an adaptive significance for the gland and offers a possible way for birds to communicate their health status through the production or composition of the secretion. More research is needed to fully understand the relationship between the anatomy of the gland in Apteryx and its function, but we propose that it plays roles in both feather maintenance and sociality

No disponible

Assimilating endocrine anatomy through simulation: a pre-emptive strike!

BACKGROUND: We sought to determine if endocrine anatomy could be learned with the aid of a hands-on, low-cost, low-fidelity surgical simulation curriculum and pre-emptive 60-second YouTube video clip. METHODS: A 3-hour endocrine surgery simulation session was held on back-to-back Fridays. A video clip was made available to the 2nd group of learners. A comprehensive 40-point test was administered before (pre-test) and after (post-test) the sessions. RESULTS: General surgery interns (n = 26) participated. The video was viewed 19 times by 80% (12 of 15) of interns with access. Viewers outperformed nonviewers on subsequent post-testing (mean [SD], 29.7 [1.3] vs 24.4 [1.6]; P = .015). Mean scores on the anatomy section of the post-test were higher among viewers than nonviewers (mean [SD] 14.2 [.9] vs 10.3 [1.0]; P = .012). CONCLUSIONS: Low-cost simulation models can be used to teach endocrine anatomy. Pre-emptive viewing of a 60-second video may have been a key factor resulting in higher post-test scores compared with controls, suggesting that the video intervention improved the educational effectiveness of the session.

Endocrine regulation and sexual differentiation of avian copulatory sexually selected characters.

Reproductive specializations in birds have provided intriguing model systems to better understand the role of endocrine mechanisms that regulate phenotype expression and the action of sexual selection. A comparative approach can elucidate how endocrine systems associated with control of sexual differentiation, sexual maturation, and reproductive physiology and behavior have diversified. Here we compare the copulatory sexually selected traits of two members of the galloanseriform superfamily: quail and ducks. Japanese quail have a non-intromittent penis, and they have evolved a unique foam gland that is known to be involved in post-copulatory sexual selection. In contrast, ducks have maintained a large intromittent penis that has evolved via copulatory male-male competition and has been elaborated in a sexually antagonistic race due to sexual conflict with females over mating. These adaptations function in concert with sex-specific and, in part, species-specific behaviors. Although the approaches to study these traits have been different, exploring the differences in neuroendocrine regulation of sexual behavior, development and seasonality of the foam gland and the penis side by side, allow us to suggest some areas where future research would be productive to better understand the evolution of novelty in sexually selected traits.

Alterations in physiology and anatomy during pregnancy.

Pregnant women undergo profound anatomical and physiological changes so that they can cope with the increased physical and metabolic demands of their pregnancies. The cardiovascular, respiratory, haematological, renal, gastrointestinal and endocrine systems all undergo important physiological alterations and adaptations needed to allow development of the fetus and to allow the mother and fetus to survive the demands of childbirth. Such alterations in anatomy and physiology may cause difficulties in interpreting signs, symptoms, and biochemical investigations, making the clinical assessment of a pregnant woman inevitably confusing but challenging. Understanding these changes is important for every practicing obstetrician, as the pathological deviations from the normal physiological alterations may not be clear-cut until an adverse outcome has resulted. Only with a sound knowledge of the physiology and anatomy changes can the care of an obstetric parturient be safely optimized for a better maternal and fetal outcome.

Ovarian and placental morphology and endocrine functions in the pregnant giraffe (Giraffa camelopardalis).

Gross, histological and immunocytochemical examinations carried out on maternal and fetal reproductive tissues from two pregnant giraffes at an estimated 8 and 13.5 months of gestation (term=15 months) revealed a typically ruminant macrocotyledonary placenta with binucleate trophoblast cells scattered sparsely in the placentome where they stained intensely with a prolactin antiserum. Binucleate cells were present in greater numbers in the intercotyledonary allantochorion where they did not stain for prolactin whereas the uninucleate trophoblast still did. A single large corpus luteum of pregnancy and several small luteinised follicles were present in the maternal ovaries while the fetal ovaries at 13.5 months gestation showed an assortment of enlarging antral follicles and partially and completely lutenised follicles, the granulosa and luteal cells of which stained positively for 3ß-hydroxysteroid dehydrogenase (3ß-HSD), 17,20 lyase, prolactin, progesterone receptor and androgen receptor, but negatively for aromatase. The uninucleate trophoblast of the placentome and intercotyledonary allantochorion, the epithelium of the maternal endometrial glands, the seminiferous epithelium in the fetal testis at 8 months of gestation and the zonae fasciculata and reticularis of the fetal adrenal at 13.5 months also stained positively for 3ß-HSD and negatively for aromatase. Endocrinologically, it appears that the giraffe placenta is more similar to that of the sheep than the cow with a placental lactogen as the likely driver of the considerable degree of luteinisation seen in both the maternal and the fetal ovaries.

Exendin-4 increases the expression of hypoxia-inducible factor-1α in rat islets and preserves the endocrine cell volume of both free and macroencapsulated islet grafts.

In this study, we evaluated the effects of exendin-4 on free and encapsulated islet grafts in a rodent model. We also investigated the role of a transcription factor, hypoxia-inducible factor-1 (HIF-1), in mediating the beneficial effects of exendin-4. Diabetic athymic mice were transplanted with free rat islets under the kidney capsule or with macroencapsulated rat islets SC with or without exendin-4, islet preculture (exendin-4 0.1 nM for 20 h), and/or recipient treatment (IP 100 ng/day, day 0-7). The mice were followed for 4 weeks and the graft function and ß-cell volume were evaluated. The effects of exendin-4 on islet HIF-1α mRNA and protein expression and on ATP content in a rat insulinoma cell line (INS-1E) were also examined. Preculture with exendin-4 followed by recipient treatment improved the outcome of both free (73% graft function vs. 26% in controls, p = 0.03) and macroencapsulated islet grafts (100% vs. 25% in controls, p = 0.02). In macroencapsulated grafts, the exendin-4-treated group had significantly larger endocrine volume, less graft necrosis, and more blood vessels around the capsule. In rat islets cultured with exendin-4, HIF-1α mRNA and protein expression were significantly enhanced. ATP content was increased in exendin-4-treated INS-1E cells under hypoxic conditions. The improved functional outcome after transplantation of a marginal islet mass with a brief initial treatment with exendin-4 is related to a larger surviving endocrine cell volume. Exendin-4 may improve islet graft resistance to hypoxia during the peritransplant period by increasing the expression of HIF-1α.

Hooked on zebrafish: insights into development and cancer of endocrine tissues.

Zebrafish is emerging as a unique model organism for studying cancer genetics and biology. For several decades zebrafish have been used to study vertebrate development, where they have made important contributions to understanding the specification and differentiation programs in many tissues. Recently, zebrafish studies have led to important insights into thyroid development, and have been used to model endocrine cancer. Zebrafish possess a unique set of attributes that make them amenable to forward and reverse genetic approaches. Zebrafish embryos develop rapidly and can be used to study specific cell lineages or the effects of chemicals on pathways or tissue development. In this review, we highlight the structure and function of endocrine organs in zebrafish and outline the major achievements in modeling cancer. Our goal is to familiarize readers with the zebrafish as a genetic model system and propose opportunities for endocrine cancer research in zebrafish.

The anatomy and physiology of the avian endocrine system.

The endocrine system of birds is comparable to that of mammals, although there are many unique aspects to consider when studying the anatomy, physiology, and biochemistry. Avian endocrinology is a field of veterinary medicine that is unfamiliar to many practitioners; however, it is important to have a comprehensive understanding when evaluating companion birds in clinical practice. This article covers the anatomy and physiology of the normal avian, and readers are referred to other articles for a more detailed explanation of altered physiology and pathology.

Effects of the androgenic growth promoter 17-beta-trenbolone on fecundity and reproductive endocrinology of the fathead minnow.

Trenbolone acetate is a synthetic steroid that is extensively used in the United States as a growth promoter in beef cattle. The acetate is administered to livestock via slow-release implants; some is converted by the animal to 17-beta-trenbolone, a relatively potent androgen receptor agonist in mammalian systems. Recent studies indicate that excreted 17-beta-trenbolone is comparatively stable in animal waste, suggesting the potential for exposure to aquatic animals via direct discharge, runoff, or both. However, little is known concerning the toxicity of trenbolone to fish. Our goal was to assess the effects of 17-beta-trenbolone on reproductive endocrinology of the fathead minnow (Pimephales promelas). An in vitro competitive binding study with the fathead minnow androgen receptor demonstrated that 17-beta-trenbolone had a higher affinity for the receptor than that of the endogenous ligand, testosterone. Male and female fish were exposed for 21 d to nominal (target) concentrations of 17-beta-trenbolone ranging from 0.005 to 50 microg/L. Fecundity of the fish was significantly reduced by exposure to measured test concentrations > or = 0.027 microg/ L. The 17-beta-trenbolone was clearly androgenic in vivo at these concentrations, as evidenced by the de novo production in females of dorsal (nuptial) tubercles, structures normally present only on the heads of mature males. Plasma steroid (testosterone and beta-estradiol) and vitellogenin concentrations in the females all were significantly reduced by exposure to 17-beta-trenbolone. The 17-beta-trenbolone also altered reproductive physiology of male fathead minnows, albeit at concentrations much higher than those producing effects in females. Males exposed to 17-beta-trenbolone at 41 microg/L (measured) exhibited decreased plasma concentrations of 11-ketotestosterone and increased concentrations of beta-estradiol and vitellogenin. Overall, our studies indicate that 17-beta-trenbolone is a potent androgen and reproductive toxicant in fish. Given the widespread use of trenbolone acetate as a growth promoter, and relative stability of its metabolites in animal wastes, further studies are warranted to assess potential ecological risk.