摘要:

AbstractRetinal connections were studied inEptesicus fuscusandArtibeus jamaicensisusing anterograde axonal degeneration and autoradiographic techniques following unilateral enucleations and uniocular injections of radioactive amino acids. Although each retina projected bilaterally to the brainstem, the number of silver grains in the emulsion of autoradiographs indicated that nearly all fibers in the optic nerve entered the contralateral optic tract. Ipsilaterally, a major portin of the projection ended in the suprachiasmatic nucleus; caudal to the suprachiasmatic nucleus, the amount of label was so small that individual silver grains were counted to determine the location and quantity of lebel in other ipsilateral nuclei. In both species the retinal projection terminated bilaterally in the suprachiasmatic, dorsal lateral geniculate, ventral lateral geniculate, and pretectal olivary nuclei and contralaterally in the posterior pretectal nucleus, superficial gray layers of the superior colliculus, and nuclei of the accessory optic system. InEptesicusthe projection to the nucleus of the optic tract ended contralaterally, and inArtibeusit ended in this nucleus bilaterally. The results of this study revealed a basic theme in the optic projection of the two ecologically different microchirop. terans. The results differed, however, in that the projection was larger and visually related nuclei were better developed inArtibeus. Such variations are presumed to relate to eye size and the relative use of vision by the two chiropterans.

ISSN:0002-9106    

DOI:10.1002/aja.1001720202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractIt seems established that under pathological conditions, microglia and blood monocytes (invading the cerebral parenchyma) behave as histiocytic cells in the central nervous system. However, it has not been clear whether or not phagocytic cells are present in normal cerebral tissue. Recently, we found a new type of cell having an uptake capacity for exogenous substance at the bifurcations of small cerebral vessels except for capillaries. According to Imamoto et al. (1982), ameboid microglia, a kind of precursor of microglia, appear at a perinatal stage and can incorporate exogenous material. In the present paper, the developmental sequences of ameboid microglia and the unique cells laden with fluorescent granules are compared at a light and electron‐microscopic level.From this study, it is clear that ameboid microglia are already present in the corpus callosum at 5 days after birth and are potent in their uptake capacity for horseradish peroxidase (HRP). However, at 2 weeks, they transform into star cells and the capacity for incorporation diminishes markedly. The finding is also supported by the quantiative analysis of transformation of ameboid microglia. At 3 months, glial cells do not take the administered HRP under the present conditions. On the other hand, fluorescent granular perithelial (FGP) cells arise from a leptomeningeal tissue (pia mater) and become situated in the perivascular spaces. They are not clearly defined at 5 days, and their uptake capacity for HRP has not yet developed. At 2 weeks, the FGP cells take definite forms with several inclusion bodies, and their uptake capacity for HRP attains a certain degree. Often, they are located at bifurcations of small blood vessels. At 3 months, the FGP cells differentiate completely in appearance, and their pinocytotic capacity reaches a high level. Consequently, the FGP cells belong to a different type of cell from that of ameboid microglia in their developmental sequences and assume a principle role of scavenging waste products in normal cerebral tissu

ISSN:0002-9106    

DOI:10.1002/aja.1001720203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractOsteopetrosis, a metabolic bone disease characterized by a generalized sclerosis of the skeleton, is inherited as an autosomal recessive in a number of mammalian species. The pathogenesis of congenital osteopetrosis is mediated by a reduction in bone resorption as a result of decreased osteoclast function. This hypothesis is based on both functional and structural evidence of reduced bone resorption in all mutations examined to date. The present study examined the histology of cartilage and bone, the ultrastructure of osteoclasts, and the morphology of mineralized bone surfaces in a lethal osteopetrotic mutation, the osteosclerotic (oc) mouse.Histologically, epiphyseal cartilage growth plates, especially the hypertrophic zone, are markedly thickened inocmice and metaphyses contain excessive osteoid, features characteristic of rickets. Transmission electron microscopy revealed that less than one‐quarter of osteoclasts inocmice demonstrated evidence of ruffled border formation compared with three‐quarters of the osteoclasts in normal littermates. In mutants, ruffled borders were less elaborate and cytoplasmic processes penetrated into bone surfaces, suggesting that bone may be removed by mechanical rather than by enzymatic means. There was little morphological evidence of cartilage degradation and broadlaminae limitantespersisted in mutants. Mineralized surfaces that undergo resorption in normal mice showed no evidence of bone resorption by scanning EM in mutants.The presence of a rachitic condition, the observations of reduced bone resorption, and the possible contribution of undermineralized matrices to decreased bone resorption are charcteristics of the osteosclerotic mutation which suggest that it is a unqiue csteopetrotic mutant in which to study both the development and regulation of skeletal metabol

ISSN:0002-9106    

DOI:10.1002/aja.1001720204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe epididymis of the bull was divided into six regions, and morphological differences between regions were studied. The epithelium of all regions contained four cell types: principal and basal epithelial cells, and intraepithelial lymphocytes and macrophages. The epithelium of regions II–V also contained a few apical cells. Principal cells of all regions possessed an endocytotic apparatus including stereocilia underlain by canaliculi, coated vesicles, and subapical vacuoles (up to 1 μm in diameter); however, large vacuoles with a flocculent content and multivesicular bodies (up to 5 μm in diameter) were most numerous in regions II, III, and IV. The unique features of principal cells of region I were the presence of well‐developed Golgi bodies, few lipid droplets, and whorls of smooth endoplasmic reticulum in the supranuclear cytoplasm. Numerous mitochondria, distended cisternae of rough endoplasmic reticulum, and dense granules characterized the infranuclear cytoplasm of the principal cells of regions II–VI; however, these features were more developed in region V. Apical cells were characterized by the apical location of the nucleus, many mitochondria in the apical cytoplasm, and few microvilli at the luminal border. Basal cells with few cytoplasmic lipid droplets were present throughout the length of the epididymis but appeared more numerous in region V. Intraepithelial lymphocytes were present at all levels of the epithelium but were never seen in the lumen. Intraepithelial macrophages containing heterogenous granules, eccentric nuclei, and pseudopods were invariably seen near the basal area of the epithelium in all regions. These observations are discussed in an effort to define the role of each cell type in the epididymal epi

ISSN:0002-9106    

DOI:10.1002/aja.1001720205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe initial stages of neovascularization of the corpus luteum were studied in cycling adult rats using light‐microscopic autoradiography. The aim of this analysis was to determine whether endothelial mitosis is a factor in this vascular growth and whether there are differences in the amount of mitotic activity in various regions of the ovary. Ovaries were examined at two time intervals: 1–2 hr and 7–8 hr following ovulation. Animals received an intraperitoneal injection of tritiated‐thymidine 20 min prior to perfusion fixation of the ovaries. Autoradiographic demonstration of tritiated‐thymidine labeling in endothelial nuclei was considered an indication of DNA synthesis preceding mitosis. The percentage of labeled endothelial cells in the ovaries at both time intervals varied according to the region of tissue examined and the stage of differentiation of that region. Stromal vessels were less heavily labeled than thecal vessels. Thecal vessels surrounding growing follicles were more heavily labeled than those surrounding atretic follicles. The heaviest labeling was seen in the developing corpora lutea 7–8 hr following ovulation. Minimal labeling was evident in the corpora lutea which were formed in previous cycles. A regional difference was also detected in the ovarian mesothelium. The portion of the mesothelium overlying ovulated follicles and developing corporalutea had the greatest percentage of labeled cells. The major findings of this study were: (1) endothelial mitosis was elevated in the initial stages of luteal neovascularization; (2) the heightened endothelial labeling was confined to specific regions of the ovary; and (3) mesothelium in close proximity to the developing corpora lutea also displayed heightened DN

ISSN:0002-9106    

DOI:10.1002/aja.1001720206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001720201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY