Design for assessment of dissection in anatomy laboratory based on group identification of structures and peer evaluation.

Dissection is a unique multisensory educational experience and is essential to learning the anatomical construction of the human and animal bodies. This study aims to introduce a specialized design for the assessment of dissection and to discuss the assessment's attributes. The design was a product of the "assessment drives learning" concept and was developed to motivate students to dissect. Students were awarded "dissection points" based on prior group dissection and identification of structures. Students' perception of the design was examined, and content analysis was performed. The assessment consisted of two parts: the first assigning each student group structures to "pin" on their previously dissected cadavers; the second was a group peer evaluation. The most critical factor for the assessment's success was careful selection of structures assigned to students to pin. The assessment was fit for the purpose, valid, reliable, and had a significant educational impact. Eighty-three percent of students (n = 116) recommended maintaining the assessment design, as they felt it promoted a deep approach to learning as well as teamwork while reducing stress to a minimum. A strong correlation (Spearman's rho = 0.46, P < 0.0001) was present between the high rating of the design and the number of structures learned, as well as, high rating and lower stress level (Spearman's rho = 0.40, P < 0.0001). There was no apparent influence of grades on student perception of the effectiveness of the assessment. This specific design of evaluation could be used as part of anatomy education in veterinary and medical schools.

Comparison of luteolysis and timed artificial insemination pregnancy rates after administration of PGF2α in the muscle or the ischiorectal fossa in cattle.

Prostaglandin F2α (PGF2α) is commonly injected intramuscularly (IM) in female cattle in synchronization protocols. A novel site for administration of PGF2α that improves beef quality assurance is the ischiorectal fossa (IRF). The objective of this study was to determine whether administration of PGF2α in the IRF results in a similar physiological response to an intramuscular injection. Yearling angus-cross heifers (n = 112) were blocked by weight and randomly assigned within blocks to be injected with 5 mL PGF2α either IM in the neck or in the IRF. Blood samples taken at 0, 8, 16, 24, 36, and 48 h post-injection were analyzed for serum progesterone concentration using a radioimmunoassay. Progesterone concentration curves for each heifer were plotted to determine luteolysis. The median times to luteolysis for neck and IRF injections were 18.1 h and 20.0 h, respectively (p = 0.06). Angus cross commercial beef cows (n = 1471) at least 30 days post-partum were blocked by age and randomly assigned within blocks to be injected with 5 mL PGF2α either IM in the neck muscle or in IRF as part of a 7-Day CO-Synch + CIDR synchronization protocol. Pregnancy diagnosis was performed via ultrasound at 60 days post insemination. Results were analyzed with Proc Glimmix (SAS). Pregnancy rates for neck and IRF injections were 52.6% and 57.2%, respectively (p = 0.06). In summary, injection of PGF2α in the IRF for synchronization of estrus and luteolysis did not differ from IM injection. Utilizing the ischiorectal fossa as an injection site for PGF2α may serve as an alternative that more closely aligns with beef quality assurance.

Light and electron microscopy of the pancreas of the Egyptian one-humped camel(Camelus dromedarius)

The exocrine portion of the pancreas consists of the pancreatic acini and their ducts. Hormones are synthesized by the cells of islets of Langerhans; they include insulin- (β- cells), glucagon- (α-cells), somatostatin- (∆-cells), and pancreatic polypeptide- (F- or PP-cells) immunoreactive cells. This study discusses the light and electron microscopic architecture of both the exocrine and endocrine pancreas of the dromedary camel. The cells of the pancreatic acini were pyramidal in shape with large spherical and centrally located heterochromatic nuclei. The basophilic basal and eosinophilic apical regions seen under the light microscope showed concentrated rough endoplasmic reticulum and homogenous electron-dense zymogen granules, respectively, on ultramicroscopy. Abundant elongated numerous mitochondria and Golgi complexes were found in the cytoplasm. The islets were scattered randomly among the acini and appeared as irregular spherical or oval masses of cells in light microscopy. The islet cells could be identified based on their location, cytological features, density of granules, and the degree to which the granule matrix was separated from its limiting membrane by an electron-dense area. The peripherally located α-cells had an irregular outline and possessed numerous relatively small membrane-bound granules with a moderate to high density core. Beta cells were larger in size and had fewer granules than of α-cells. Halo areas surrounded the moderate electron-dense granules. The polygonal ∆-cells were found in clumps throughout the islet and in between β-cells. Their granules were of moderate electron density and were tightly enclosed by a limiting membrane. Pancreatic polypeptide cells were seen associated with α and β cells. They were irregular small cells with small granules and dark cytoplasm. The juxtaposition of the endocrine and exocrine elements of the pancreas can be traced back to their embryological origin and can be also of functional significance. It facilitates the mutual functional interaction of both portions of the pancreas

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Immunohistochemical identification of the endocrine cells in the pancreatic islets of the camel, horse and cattle

This study considers the distribution of various endocrine cells in islets of Langerhans in the pancreas of several species of domestic animal, including the dromedary camel (Camelus dromedarius) using immunohistochemistry, and relates our observations with reference to the well-documented general histology of the mammalian pancreas. The pancreatic islets were observed as compact areas of pale cells surrounded by darker presumably exocrine tissue. The most distinct delineation of the islets from the surrounding acini was in the horse and the least was in cattle. Insulin-immunoreactive cells (β-cells) were most abundant followed by glucagon- (α-), somatostatin- (∆-), and pancreatic polypeptide-immunoreactive (F- or PP-) cells in decreasing order, in all species except cattle where PP-cells were second to β-cells in their distribution. The most prominent special pattern was observed in the distribution of α- and β- cells in the pancreatic islet of the horse where α-cells were located in the center of the islet surrounded by β-cells. In the camel, β-cells were distributed throughout the islet in the center and the periphery. Alpha cells were mostly observed as clumps in the periphery area. Clumps of small number of ∆-cells and a few PP cells were found throughout the islet. In cattle, β-cells were distributed throughout the islets. Other cells occupied a more peripheral location. The physical differences in distribution of endocrine cells might result in differences in the need and interaction of hormones to each other in different species

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Microscopic anatomy and ultrastructure of the ureter of the Camelus Dromedarius ureter

The histology and ultrastructure of the ureter of Camelus dromedarius were investigated. The ureteric wall included a tunica mucosa of transitional epithelium (urothelium); an underlying loose connective tissue layer (propriasubmucosa); a tunica muscularis of smooth muscle forming inner longitudinal, middle circular, and outer longitudinal layers; and a tunica adventitia or a tunica serosa. The smooth muscle layer of the renal pelvis was scarce or lacking. The urothelium consisted of basal cuboidal to columnar cells, intermediate cells, and larger, pale superficial cells with small nuclei. The epithelium of the renal pelvis was only a few cells deep. The transitional epithelium appeared to be adapted for extensibility and water impermeability. The cytoplasm of the superficial and intermediate cells contained many membrane-bound vesicles. Junctional complexes were seen between the lateral membranes of the superficial cells providing a barrier to the passage of substances and urine into the ureteric wall. The junctional complexes and the membrane-bound vesicles may play an important role in membrane turnover and in regulating the expansion and contraction of the urothelium. In this study, we report the presence of submucosal glands in the renal pelvis of Camelus dromedarius. The serous nature of the submucosal glands, seen under the light microscope, was confirmed with the electron microscope. These glands had nearly pyramidalshaped cells lying on a basement membrane and a lumen. The cells of the epithelial lining were mainly dark with a central spherical nucleus. A connective tissue capsule could be seen around the gland (AU)

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Maternal and fetal microvasculature in sheep placenta at several stages of gestation.

Maternal and fetal microvasculature was studied in ewes at days 50, 90 and 130 of gestation using microvascular corrosion casting and scanning electron microscopy. Microvascular corrosion casts of caruncles at day 50 were cup-shaped with a centrally located cavity. Branches of radial arteries entered the caruncle from its base and ramified on the maternal surface of the caruncle. Stem arteries broke into an extensive mesh of capillaries forming crypts on the fetal surface. The architecture of the caruncle at day 90 was similar to what was found at day 50 but the vascularity and the depth of the crypts increased in correspondence to increased branching of fetal villi. The substance of the caruncle was thicker at day 130 compared with day 50, with no remarkable difference compared with day 90. Capillary sinusoids of irregular form and diameter were observed on the fetal surface of the caruncle at all stages. These sinusoids may reduce blood flow resistance and subsequently increase transplacental exchange capacity. A microvascular corrosion cast of the cotyledon was cup-shaped with wide and narrow sides. Cotyledonary vessels entered and left the cotyledon from the narrow side. A cotyledonary artery gave proximal collateral branches immediately after entering the cotyledon and then further branched to supply the remaining portion of the cotyledon. Vessel branches broke into a mesh of capillaries forming the fetal vascular villi. Fetal villi that were nearest to the center of the cotyledon were the longest. Capillaries forming villi were in the form of a web-like mesh, were irregular in size and had sinusoidal dilations. The architecture of the cotyledon at day 90 was similar to day 50, but the vascularity increased. Branching of the fetal villi became more abundant. This extensive branching presumably allows a higher degree of invasion and surface contact to maternal tissues. At day 130, the distal portions of the fetal villi showed low ridges and troughs to increase the surface area for diffusion. Branching of fetal villi appears to influence the elaboration of maternal crypts in all stages of gestation. However, correspondence between crypts and villi is restricted to distal portions of fetal villi.

Uteroplacental vascular development and placental function: an update.

The importance of the placenta and its vascular development to fetal growth and development has been appreciated since ancient times. Based on numerous studies in humans and animal model organisms in the last 2-3 decades, normal placental angiogenesis is critically important to ensure adequate blood flow to the placenta and therefore to provide the substrates that support normal fetal growth. Placental angiogenesis is abnormal at term in compromised pregnancies (those in which fetal growth is altered), including those resulting from maternal nutritional or environmental stress, maternal age, increased numbers of fetuses, maternal or fetal genotype, or the use of assisted reproductive technologies (e.g., cloning by somatic cell nuclear transfer). We and others have recently shown that these defects in placental vascular development occur quite early in pregnancy and may therefore presage compromised fetal growth and development. The challenges will be to find biomarkers of abnormal placental angiogenesis and to develop therapeutic strategies to "rescue" placental vascular development and thus fetal growth in compromised pregnancies. Animal models will be essential in meeting these challenges.

Chapter 10. Methods for evaluating uteroplacental angiogenesis and their application using animal models.

In this chapter, we present some of the compelling evidence confirming the importance of placental angiogenesis to fetal growth and development in normal and compromised pregnancies. We then describe the methodology that has been used to evaluate placental angiogenesis throughout pregnancy, including both the practical methods used to obtain reliable samples of the placental microcirculation as well as computerized methods used to analyze and reconstruct it. We then briefly describe the changes in placental angiogenesis and function in the models of normal and compromised pregnancy that we have used, and conclude with what we have learned from these studies and what we believe are the larger questions remaining.

Study of the vasculature of the caprine reproductive organs using the tissue-clearing technique, with special reference to the angioarchitecture of the utero-ovarian vessels and the adaptation of the ovarian and/or vaginal arteries to multiple pregnancies.

Arteries of the reproductive tracts of nonpregnant does and does at 4, 7, 10, 13, 16, and 18 weeks of gestation were injected in situ with Microfil. The tracts were fixed, dehydrated, and rendered transparent to reveal the paths of arteries. The tortuous ovarian artery lay in close apposition to the uterine tributary of the ovarian vein, an arrangement that may serve as a local utero-ovarian pathway for the corpus luteum (CL) luteolysis at the end of nonfertile estrous cycle. During pregnancy, this arteriovenous arrangement might transfer luteotropic substances from uterus to ovary, which might serve in maternal recognition of pregnancy and fit the fact that the goat is CL-dependent throughout gestation. In some cases of triplets, the size of the uterine branch of the ovarian artery was equal to or even larger than that of its parent artery and/or the ipsilateral uterine artery, and the vaginal artery contributed a connecting branch to the uterine artery. These physiological adaptations of the ovarian and/or vaginal arteries, which have not previously been described, correlate well with the increasing nutrient demands of the growing multiple fetuses.