摘要:

AbstractAnterior pituitary cells exhibiting growth hormone (GH) immunoreactivity and forebrain neurons containing growth hormonereleasing hormone (GHRH) immunoreactivity were identified in little brown bats (Myotis lucifugus) using light microscopic immunocytochemistry. Pituitary somatotropes appeared as ovoid or polyhedral cells that were distributed throughout most of the pars distalis, with the exception of its most rostral region where this cell type was scarce. GH‐immunoreactive cells occupied approximately one‐third of the total volume of the pars distalis; this proportion did not differ significantly between males and females or in bats collected at different times of year. Neuronal perikarya containing immunoreactive GHRH were observed in the hypothalamic arcuate and suprachiasmatic nuclei, as well as in the cortical and subcortical telencephalon. Fibers were most evident in the median eminence, paraventricular and periventricular nuclei, and molecular layer of the cerebral cortex. Fine fibers were also accumulated in the bed nucleus of the stria terminalis and in the amygd

ISSN:0002-9106    

DOI:10.1002/aja.1001900102

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe structure and function of colonic mucosal lymphoid organs remain largely unexplored, especially in the rectum hidden within the pelvic vault. Two‐month‐old female BALB/c mice were anesthetized, and the entire colon was removed from cecum to anus. Distal colonic patches were then prepared for electron microscopy or were quick‐frozen and sectioned for immunoperoxidase localization of B cells and T cell subsets. Aggregated lymphoid follicles were distributed irregularly along the entire colon with an average of 1.4 patches per centimeter of colon length. There were large collections of follicles opposite the ileocecal valve (cecal patches), variable numbers of patches throughout the colon, and at least one patch within 10 mm of the anus (rectal patch). Follicles were adjacent to branching crypts lined by epithelium infiltrated by lymphoid cells and containing few goblet cells. In electron micrographs, M cells were identified by their short, irregular microvilli; intraepithelial lymphoid cells; reduced lysosomal dense bodies; and an expanded tubulovesicular network. Small germinal centers were seen. Cytoarchitectural components of colonic lymphoid follicles and Peyer's patch follicles were remarkably similar, despite differences in surrounding mucosa and luminal microbial exposure. The presence of organized lymphoid tissue with M cells and germinal centers suggests that transepithelial particle transport and antigen recognition can take place in the rectum. Whether such tissue has the capacity for uptake of luminal microorganisms is of particular interest, not only because colonic follicles may be sites for local initiation of immune responses but also because they may be important entry points for systemic infe

ISSN:0002-9106    

DOI:10.1002/aja.1001900103

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe present view is that glucocorticoid hormones bind to their cytoplasmic receptors before reaching their nuclear target sites, which include specific DNA sequences. Although it is believed that cytoplasmic sequestration of steroid receptors and other transcription factors (such as NFKB) may regulate the overall activity of these factors, there is little information on the exact subcellular sites of steroid receptors or even of any other transcription factors. Tritiated (3H)‐dexamethasone 21‐mesylate (DM) is an affinity label that binds covalently to the glucocorticoid receptor (GR), thereby allowing morphological localization of the receptor at the light and electron microscope levels as well as for quantitative radioautographic (RAG) analysis. After injection of3H‐DM into the testis, a specific radioautographic signal was observed in Leydig cells, which correlated with a high level of immunocytochemically demonstrable GR in these cells at the light‐microscope level. To localize the3H‐DM binding sites at the electron microscope (EM) level, the testes of 5 experimental and 3 control adrenalectomized rats were injected directly with 20 μCi3H‐DM; control rats received simultaneously a 25‐fold excess of unlabeled dexamethasone; 15 min later, rats were fixed with glutaraldehyde and the tissue was processed for EM RAG analysis combined with quantitative morphometry. The radioautographs showed that the cytosol, nucleus, smooth endoplasmic reticulum (sER), and mitochondria were labeled. Since the cytosol was always adjacent to tubules of the sER, the term sER‐rich cytosol was used to represent label over sER networks, which may also represent cytosol labeling due to the limited resolution of the radioautographic technique. Labeling was highest in sER‐rich cytosol and mitochondria, at 53% and 31% of the total, respectively. Cytosol (exclusively of all organelles) and nucleus showed comparatively weak labeling, at 9% and 7%, respectively. This study thus clearly establishes with the electron microscope, the localization of glucocorticoid binding sites using DM. It remains to be determined whether or not these DM binding sites represent bona fide glucocorticoid receptors or nonreceptor proteins that bind DM. Whereas the functional significance of the subcellular distribution of DM is not known, the labeling of the cytosol may represent localization of the steroid and GR in their traditional compartment. The steroid antagonistic properties of DM may have prevented the DM‐GR complexes from translocating to the nucleus. However, the significant labeling of the sER‐rich cytosol and mitochondria was unexpected and raises intriguing questions that are being addres

ISSN:0002-9106    

DOI:10.1002/aja.1001900104

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

年代:1991

数据来源: WILEY

摘要:

AbstractCryostat‐ and vibratome‐cut rat kidney secretions were singly or doubly labeled to visualize immunoreactive calcitonin‐gene‐related peptide (CGRPI) and substance P (SPI). Rats were perfused with 2–4% paraformaldehyde + 0.15% picric acid then rinsed with buffer. Horseradish peroxidase (HRP) was used to visualize CGRP in vibratome sections, and combined HRP and fluorophore were used to visualize the two peptides simultaneously in cryostat sections. There is a complex, multilayered plexus of CGRP nerves on the renal pelvis and a less dense, single‐layered plexus on the major branches of the renal artery and on interlobar arteries and veins. A few axons innervate finer branches of the arterial tree and other intrarenal structures. Results of double immunolabeling suggest that SPI axons comprise a subpopulation of the CGRP axon population in the rat kidney. There was no evidence for a separate population o

ISSN:0002-9106    

DOI:10.1002/aja.1001900105

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe mandibular condyle from 20‐day‐old rats was examined in the electron microscope with particular attention to intracellular secretory granules and extracellular matrix. Moreover, type II collagen was localized by an immunoperoxidase method.The condyle has been divided into five layers: (1) the most superficial, articular layer, (2) polymorphic cell layer, (3) flattened cell layer, (4) upper hypertrophic, and (5) lower hypertrophic cell layers. In the articular layer, the cells seldom divide, but in the polymorphic layer and upper part of the flattened cell layer, mitosis gives rise to new cells. In these layers, cells produce two types of secretory granules, usually in distinct stacks of the Golgi apparatus: typea, cylindrical granules, in which 300‐nm‐long threads are packed in bundles which appear “lucent” after formaldehyde fixation; and typeb, spherical granules loaded with short, dotted filaments. The matrix is composed of thick banded “lucent” fibrils in a loose feltwork of short, dotted filaments.The cells arising from mitosis undergo endochondral differentiation, which begins in the lower part of the flattened cell layer and is completed in the upper hypertrophic cell layer; it is followed by gradual cell degeneration in the lower hypertrophic cell layer. The cells produce two main types of secretory granules: typebas above; and typec, ovoid granules containing 300‐nm‐long threads associated with short, dotted filaments. A possibly different secretory granule, typed, dense and cigar‐shaped, is also produced. The matrix is composed of thin banded fibrils in a dense feltwork.In the matrix of the superficial layers, the “lucency” of the fibrils indicated that they were composed of collagen I, whereas the “lucency” of the cylindrical secretory granules suggested that they transported collagen I precursors to the matrix. Moreover, the use of ruthenium red indicated that the feltwork was composed of proteoglycan; the dotted filaments packed in spherical granules were similar to, and presumably the source of, the matrix feltwork. The superficial layers did not contain collagen II and were collectively referred to asperichondrium. In the deep layers, the ovoid secretory granules displayed collagen II antigenicity and were likely to transport precursors of this collagen to the matrix, where it appeared in the thin banded fibrils. That these granules also carried proteoglycan to the matrix was suggested by their content of short dotted filaments. Thus the deep layers contained collagen II and proteoglycan as in cartilage; they were collectively referred to a

ISSN:0002-9106    

DOI:10.1002/aja.1001900106

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe neuroanatomical organization of the dynamic (bag1) and static (bag2and chain) intrafusal systems was compared by light and electron microscopy of serial sections among 71 poles of muscle spindle in soleus (SOL), extensor digitorum longus (EDL), and lumbrical (LUM) muscles in the rat. Eighty‐four percent of 195 fusi‐motor (γ) axons to the spindles innervated either the dynamic bag1fiber or the static bag2and/or chain fibers. Sixteen percent of the γ axons coin‐nervated the dynamic and static intrafusal fibers. Some of these nonselective axons were branches of efferents that also gave rise to axons selective to either the dynamic or static types of intrafusal fibers in one or more spindles. Thus activation of individual stem γ efferents might not have a purely dynamic or purely static effect on the integrated afferent outflow from spindles of a hind‐limb muscle in the rat. In addition, primary afferents in all muscles had terminations that cross‐innervated the dynamic bag1and static bag2and/or chain intrafusal fibers in individual spindles, an arrangement that may enhance the mixed dynamic/static behavior of afferents when different intrafusal fibers are activated concurrently. Spindles of the slow SOL and fast EDL muscles had similar features, whereas differences were observed in the organization of the proximal (SOL and EDL) and distal (LUM) muscles. Spindles in LUM muscles had fewer static intrafusal fibers, a higher ratio of dynamic to static γ axons, and a higher incidence of skeletofusimotor (β) innervation to intrafusal fibers than spindles in the SOL or EDL muscles. Thus, the relative contribution of dynamic and static systems to muscle afferent outflow may differ among spindles located in different segments of the rat hindlimb. However, the dynamic and static intrafusal systems of spindle were less sharply demarcated in each of the three hindlimb rat muscles than in the cat tenu

ISSN:0002-9106    

DOI:10.1002/aja.1001900107

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

年代:1991

数据来源: WILEY

摘要:

AbstractWe have studied the subcellular distribution of ferritin in inflammatory macrophages present in regional lymph nodes from dogs subjected to a pulmonary inflammatory reaction. The inflammatory reaction was induced by intrabronchial instillation of calcium tungstate (CaWO4), a water‐insoluble powder. Ferritin was identified by electron microscopy, and its electron density was enhanced by the use of a modified Perls method. From day 14 on after the CaWO4deposition, tungsten‐positive lymph node macrophages showed a massive accumulation of ferritin. Most of the ferritin was stored in membrane‐bounded vesicles that showed heterogeneous concentrations of the protein. A significant complement of ferritin was also detected in the cytoplasmic ground substance of phagocytes. The cell surface of the ferritin‐rich, tungsten‐positive macrophages showed deep infoldings that encompassed small pockets of connective tissue fibers. These features were not observed in control samples or in lymph nodes from dogs subjected to CaWO4‐induced inflammation for periods shorter than 1 week. Our data indicate that inflammatory macrophages greatly increase their content of ferritin and that ferritin is stored predominantly by a membrane‐bounded vesicular compartment. This is in contrast with suggestions that the inflammation‐induced increase in macrophage iron is restricted to the labile pool of iron and it does not involve the iron bound to ferritin molecules. Our observation of nodules of connective‐tissue fibers in intimate topographical association with ferritin‐rich macrophages may indicate that the increase in intracellular ferritin in the macrophage is in some way related to the secretion of factors by the phagocyte that will stimulate fibrillogenesis by neig

ISSN:0002-9106    

DOI:10.1002/aja.1001900108

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

年代:1991

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001900101

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

年代:1991

数据来源: WILEY