摘要:

AbstractThe sino‐auricular nodal tissue of the heart of the loach (Misgurnus anguillicaudatus, Cantor) contains (1) myocardial cells receiving rich innervation, (2) isolated nerve cells, and (3) cardiac internuncial cells which are interposed between autonomic axon terminals and myocardial cells. Structural specializations are noted at the synapse between the autonomic axon and the myocardial cell, as well as at the axon‐internuncial cell synapse. Between the internuncial cell and the myocardial cell, attachment plaques are present with a patchy locus of a close junction, wherein the extracellular space appears to be almost obliterated. Estimations were made of the surface areas of an internuncial cell body and a nerve cell body as revealed by serial sampling of the tissue at about 0.5 μ intervals. The results show that for an internuncial cell body followed over a length of 15 μ, 52.5% of its total surface is covered by vesiculated axons, 3.8% by non‐vesiculated axons, 12.2% by myocardial cells, and 3.1% by Schwann cell processes; for a nerve cell body followed over a length of 16 μ, only 1.8% is covered by vesiculated axons, 0.5% by non‐vesiculated axons, nil by myocardial cells, and 96.4% by a satellite cell and its processes. It is considered that the internuncial cell represents a specialized cell type in the nodal tissue of the fish heart, playing a role in modulating the autonomic nerve impulses before they are transmitted to the effector myocar

ISSN:0002-9106    

DOI:10.1002/aja.1001380402

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

年代:1973

数据来源: WILEY

摘要:

AbstractChronic treatment with isoproterenol, a β‐adrenergic drug, accelerates the postnatal differentiation of the rat submandibular gland. This report compares the ultrastructure of submandibular glands of acute and chronically treated, 2, 11 and 17‐day‐old rats with that of controls. In all cases a greater number of acinar cells were found in the treated glands. The correlation noted between changes in the nature of the contents of the condensing vaculoes and Golgi apparatus of some proacinar cells and the formation of secretory granules intermediate in appearance between those of proacinar and acinar cells, support the hypothesis that proacinar cells are the precursors of acinar cells in the young rat. Differences in the morphology of secretory granules in acinar cells of treated and control animals are described. It is concluded that precocious differentiation of the submandibular gland may be induced by the administration of isoproterenol as early as the first day of postnatal life, that proacinar cells become recognized as acinar cells following a change in the nature of their secretory product, and that the secretory material produced by acinar cells in the treated animals is not identical to that of the co

ISSN:0002-9106    

DOI:10.1002/aja.1001380403

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe effects of phenobarbital on development of some microsomal enzymes and neutral lipid were studied in mouse liver during a period of rapid cell differentiation. Specific alterations attributable to phenobarbital were identified in developing liver and used as markers for the onset of certain aspects of cell maturation. This investigation was designed to determine (1) the earliest developmental age at which fetal liver can react to phenobarbital and (2) the nature of the alterations in developing and adult liver.Intraperitoneal injections of phenobarbital were given for three days to 14, 17 and 19 day pregnant mice. Histochemical techniques were used to localize neutral lipid and the activities of NADPH diaphorase, glucose‐6‐phosphatase, and glucose‐6‐phosphate dehydrogenase. Total cell lipid was measured in livers from 17‐ and 19‐day pregnant mice and livers from their fetuses.The density of reaction product for NADPH diaphorase and glucose‐6‐phosphate dehydrogenase increased while glucose‐6‐phosphatase decreased in adult liver. Similar changes were seen in livers from day‐19 fetal animals but not in fetuses of younger ages. Neutral lipid droplets increased in size and number after phenobarbital in fetal mice of day 19 of gestation but not in mice of day 17 of gestation.It was concluded that liver from day‐19 fetal mice had gained the competence, lacking in earlier ages, to respond to phenobarbital by increased production of some en

ISSN:0002-9106    

DOI:10.1002/aja.1001380404

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

年代:1973

数据来源: WILEY

摘要:

AbstractWith few exceptions, anatomical studies of amphibian lateral line systems have been limited to gross and light microscopic investigations. The lateral line of Xenopus laevis had been studied at the fine structural level, but electron microscopic data are available only for late larval and adult stages. A comparison of the ultrastructure of lateral line receptor cells at different stages in the life histories of urodele species indicates that four categories of large (to 3 μ diameter) organelles occur in these animals. Apical and synaptic dense bodies are morphologically similar but lie at opposite ends of the cell. Lysosomes and multivesicular bodies are concentrated in regions of the Golgi apparatus. Previously undescribed perinuclear crystalline inclusions seem to be associated with bundles of microfilaments. Inclusions of similar internal structure also occur within the nucleus. The location of a crystalline structure in the nucleus makes the definition of a more typical nucleolus mandatory

ISSN:0002-9106    

DOI:10.1002/aja.1001380405

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

年代:1973

数据来源: WILEY

摘要:

AbstractSplenic islets of Anolis carolinensis incubated in an in vitro perifusion system with media containing a non‐stimulatory concentration of glucose had the same ultrastructural appearance as islets removed from an intact animal. When horseradish peroxidase was included in this medium, no profiles suggestive of emiocytotic release of B granules were observed despite basal insulin secretion.With cytochalasin B and a high concentration of glucose, the B cells exhibited margination of their secretory granules and moderate degranulation, but rarely were profiles suggestive of emiocytosis seen. In the presence of cytochalasin B, glucose and the other insulin secretagogues used, the B cells were more degranulated than with only cytochalasin B and glucose present, but profiles indicative of emiocytosis were infrequently encountered. Emiocytosis of the B granules was demostrated convincingly with the inclusion of peroxidase and the above agents. Virtually all the B cells had at least one secretory granule fused with the limiting membrane and surrounded by the peroxidase, and some B cells exhibited multiple release of granules. From these observations it is concluded that emiocytosis plays a major role in the secretion of insulin from B cells of Anolis.The B cells from control perifusions, as well as from intact animals, did not contain a microfilamentous cell web. Granular or filamentous masses were not demonstrated in B cells from splenic islets perifused with cytochalasin B. The mechanism of emiocytotic release of insulin from the B cells of Anolis is discussed with reference to these observation

ISSN:0002-9106    

DOI:10.1002/aja.1001380406

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe immunological and cytological specificity of antiserum to adrenocorticotrophic hormone was established and the corticotroph defined at the light microscopic level by immunocytochemistry. Our observations substantiated recent reports by several investigators. By comparing thin methacrylate sections with adjacent 1 μ‐methacrylate sections immunochemically stained with anti‐ACTH, the ACTH cell was identified at the ultrastructural level and its morphology studied. Using the criteria established at light and electron microscopic levels, the corticotroph was readily found in tissue which had been fixed in paraformaldehyde‐osmium mixture and embedded in epoxy resin. Ultrastructural changes in this cell in response to experimentally designed alterations in the pituitary ACTH levels confirmed this identification. The ACTH cell was likewise identified in glutaraldehyde‐fixed material. Thyrotrophs were tentatively defined. Several ultrastructural studies responsible for conflicting reports in the literature were investigated. It was concluded that the corticotroph is a unique cell type and that granule size and morphology remain important criteria for adenohypophyseal cell identification regardless of the fixation used. The need for a definitive immunocytochemical study of thyrotrophs at the ultrastructural level was re

ISSN:0002-9106    

DOI:10.1002/aja.1001380407

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

年代:1973

数据来源: WILEY

摘要:

AbstractColloidal gold marker was present in the capillary lumen and at various stages of pinocytosis and passage through the endothelial cells. It was occasionally located in the peri‐endothelial space, close to the basement membrane. The uptake of marker by other cells was not observed. These results suggest the existence of two barriers, the biological (pinocytotic and hydrolytic capacities of the endothelial cells) and mechanical (permeability of the basement membrane

ISSN:0002-9106    

DOI:10.1002/aja.1001380408

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

年代:1973

数据来源: WILEY

摘要:

AbstractElectron micrographs of synapses stained with an ethanolic solution of phosphotungstic acid have been subjected to equidensitometric analysis by the recently developed Agfacontour Professional film. Subtle variations in the staining of presynaptic dense projections and postsynaptic structures have been detected. Morphometry of these micrographs has been facilitated by this technique which is rapid and obviates the need for expensive and complex electronic equipment.

ISSN:0002-9106    

DOI:10.1002/aja.1001380409

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

年代:1973

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001380401

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

年代:1973

数据来源: WILEY