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Ultrahistochemical studies on the plasma membrane of stratum corneum cells in the proventricular epithelium of the goat Using ultrahistochemical methods carbohydrate-rich substances and SH-groups could be localized on the plasma membrane of stratum corneum cells in the proventricular epithelium of the goat. SH-groups were present only on the inner lamella of the plasma membrane while mucosubstances were present on both sides. The functional significance of both these substances is still not understood, especially whether they take part in the specific transport mechanism present in the proventricular epithelium. 相似文献
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The canalis alimentarius of the Burunduk (Eutamias sibiricus), a rodent belonging to the family Sciuridae, were examined macroscopically (12 animals) and light microscopically (three animals). The esophagus is lined with a stratified non-keratinized squamous epithelium. The one-chambered stomach is of a simple type covered with a glandular mucous membrane. When empty and moderately filled, the stomach looks like a curved sack and lies intrathoracally. The filled stomach extends to the left and ventrally into the regio abdominis media. The greater omentum covers incompletely ventrally and in a part laterally the intestinal mass. The intestinal canal averages about 780 mm in length, that is 6.5 as long as the whole body. The relative length of the small intestine compared with the large intestine is 36-64%. The U-shaped Duodenum is composed of a Pars cranialis, descendens and ascendens and possesses a Plica duodenocolica as well as a Plica duodenocolica accessoria. The Jejunum averages about 420 mm length and is mainly located in the right and ventral part of the regio abdominis media. As in other rodents, the cecum is well developed. The length of the ascending colon averages about the body length and forms an Ansa proximalis and two parallel loops, Ansa media and Ansa distalis coli, both lying in the right Cavum abdominis. Peculiar for the colon are Noduli lymphatici solitarii surrounding cavities lined by a surface epithelium. According to the anatomical structure of the gut and based on physiological diet facts the Burunduk is not a mere herbivore but has to be classified as an omnivore depending upon uptake of animal food protein. 相似文献
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Arterioles, precapillary sphincters, capillary endothelium, and pericytes probably regulate the blood flow in the intestinal microvascular bed similar to other regions of the body because of their equipment with contractile filaments. Only throttle veins with their arrangement of pools and their characteristics probably exert influence on the hemodynamic qualities of the blood flow in the intestinal mucosa. 相似文献
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Angelika Brandt Bertram Schnorr Dietrich Weyrauch 《Anatomia, histologia, embryologia》1983,12(1):7-24
The ultrastructure of the adipose tissue connective tissue, mesothelium and milky spots forming the greater cmentum of sheep and goats was studied.
The mixture of connective tissue fibers and adipose tissue is arranged in submesothelial, marginal, and central layers. – The mesothelial cells are covered by a surface coat and are characterized by numerous microvilli and vesicles. The number of milky spots varies greatly. They are commonly found on the surface of the omentum and are covered by modified mesothelial cells; their interior contains macrophages and lymphoid cells. 相似文献
The mixture of connective tissue fibers and adipose tissue is arranged in submesothelial, marginal, and central layers. – The mesothelial cells are covered by a surface coat and are characterized by numerous microvilli and vesicles. The number of milky spots varies greatly. They are commonly found on the surface of the omentum and are covered by modified mesothelial cells; their interior contains macrophages and lymphoid cells. 相似文献
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The prenatal development of the bovine ruminal epithelium was studied with light- and electronmicroscopical techniques. During the period of the nonstratified epithelium a pseudostratified epithelium is found in the dorso-cranial part, whereas the other areas possess a one-layered epithelium, which is, like the pseudostratified epithelium, transformed to a multilayered epithelium from the 7th week onwards. From the 9th week the period of the stratified epithelium starts with the formation of the stratum profundum and stratum superficiale. First signs of keratinization are seen in the superficial cells from 2.3 months onwards. With 4 months fetal cornified cells can be identified, with 5.5 months a single-layered stratum basale is seen on the differentiating papillar connective tissue, and the superficial cells are transformed to balloon-cells. In suprapapillar areas, a stratum spinosum is formed at the prenatal age of 7.5 months. During epitheliogenesis a horizontal and vertical differentiation of the cells can be observed. The first one includes the differentiation of undifferentiated, embryonal cells to the basal cells of the stratum profundum, the latter the development of the basal cells to spinous cells and then to fetal cornified and balloon-cells. The ultrastructural changes during the process of keratinization were especially considered. 相似文献
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Chlamydial vaccines 总被引：1，自引：0，他引：1
K L Schnorr 《Journal of the American Veterinary Medical Association》1989,195(11):1548-1561
With few exceptions, immunity from chlamydiosis availed by current vaccines is limited and can even be detrimental. Possible reasons for failure include immunotype or strain differences, ill-defined virulence variation, presentation of deleterious antigens, and incorrect presentation of critical antigens to the body. Antigens that stimulate neutralizing antibodies active at 2 steps of infection have been identified. A third step, prevention of phagolysosomal fusion, needs to be further studied, and causal antigens need to be identified. A fourth possible stage for antibody participation is in antibody-dependent cell-mediated cytotoxicity. If chlamydial antigens are expressed on the surface of infected cells, this mechanism of destruction of infected cells and the antigens that elicit it will need to be more fully examined. Cell-mediated immune responses participating in eliminating chlamydial infections need to be further clarified. Activated macrophages are the best characterized effector mechanism of cell-mediated immunity thus far, regardless of the stimulatory cytokines involved. It is important to determine how sensitized lymphocytes recognize antigen(s) that cause them to release macrophage-activating cytokines. It must be determined whether chlamydial antigens are expressed on the surface of infected cells and then recognized by potential cytokine-releasing lymphocytes in context with major histocompatibility antigens (surface expression) or whether they are recognized on antigen-presenting cells functioning in more of a scavenging capacity. Membrane expression of antigen is also important in that it also defines whether cytotoxic T cells and antibody-dependent cell-mediated cytotoxicity have roles in resistance to chlamydial infection. Also, it is important to realize the possible limitation of these mechanisms to systemic sites of the body. If membrane expression does occur, it must be determined how it functions at mucosal sites, whether it occurs at the luminal surface of mucosal epithelial cells only, or whether there is expression of antigens at abluminal membrane surfaces perhaps more accessible to such immune effector mechanisms. Delivery of critical antigens to the individual is the final component in establishing effective vaccines. Carrier systems capable of stimulating long-lasting mucosal and systemic immunity are available and need to be further studied as protective immunogens become available. 相似文献
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Introduction and Aim: The corpus luteum is one of the most intensely vascularized tissues. Luteal angiogenesis is strictly controlled and blood vessels regress completely within a short period of time. The aim of this study was to investigate vascular dynamics in relation to cellular and molecular mechanisms of luteal angiogenesis and anti-angiogenesis.
Material and Methods: Endothelial cells of blood vessels in paraffin sections of bovine corpora lutea from different stages were examined by labelling with the lectin Bandeiraea simplicifolia agglutinin I. Angiogenesis was studied by morphometry of the capillaries, and immunolocalization of the angiogenic factor VEGF and VEGF-receptor 2. Presence of apoptotic luteal and endothelial cells was investigated using the TUNEL test and transmission electron microscopy.
Results: During development of the corpus luteum (day 3–8 of the oestrous cycle) a dense capillary network (8–12% area ratio) is established and maintained until day 17. Early regression (day 18–24) is characterized by a remarkable decrease of capillaries (1% area ratio). In the regressing corpus luteum the number of apoptotic luteal cells is closely correlated ( r = 0.9) to the number of apoptotic endothelial cells. VEGF is immunolocalized in luteal cells (day 3–17), smooth muscle cells and endothelial cells of arterioles of the regressing corpus luteum. During late luteal regression, a moderate increase of capillaries (2.5% area ratio) is obvious.
Conclusions: The dynamic changes of the capillarity during development and regression of the cyclic corpus luteum correlate with VEGF and VEGF-R2 activities. In contrary to expectations the late stage of luteal regression is accompanied by angiogenesis. One reason for this phenomenon may be an increase in metabolic activity resulting in re-organization of blood vessels already regressed. 相似文献
Material and Methods: Endothelial cells of blood vessels in paraffin sections of bovine corpora lutea from different stages were examined by labelling with the lectin Bandeiraea simplicifolia agglutinin I. Angiogenesis was studied by morphometry of the capillaries, and immunolocalization of the angiogenic factor VEGF and VEGF-receptor 2. Presence of apoptotic luteal and endothelial cells was investigated using the TUNEL test and transmission electron microscopy.
Results: During development of the corpus luteum (day 3–8 of the oestrous cycle) a dense capillary network (8–12% area ratio) is established and maintained until day 17. Early regression (day 18–24) is characterized by a remarkable decrease of capillaries (1% area ratio). In the regressing corpus luteum the number of apoptotic luteal cells is closely correlated ( r = 0.9) to the number of apoptotic endothelial cells. VEGF is immunolocalized in luteal cells (day 3–17), smooth muscle cells and endothelial cells of arterioles of the regressing corpus luteum. During late luteal regression, a moderate increase of capillaries (2.5% area ratio) is obvious.
Conclusions: The dynamic changes of the capillarity during development and regression of the cyclic corpus luteum correlate with VEGF and VEGF-R2 activities. In contrary to expectations the late stage of luteal regression is accompanied by angiogenesis. One reason for this phenomenon may be an increase in metabolic activity resulting in re-organization of blood vessels already regressed. 相似文献
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