摘要:

AbstractThe small intestines of adult rats were examined by light and scanning‐electron microscopy after sublethal doses of methotrexate were injected at 5, 3 and 1 mg, respectively, per rat per day, for three days. Methotrexate inhibited mitosis and thereby disrupted the steady state system of the epithelium. Villi and crypts progressively diminished up to about four and one‐half days after the initial injection. Thereafter, recovery began and, by day 7, relatively normal morphology was restored. In the degenerative phase, the loss of crypt‐villus continuum was frequently observed, the former crypts forming cyst‐like structures. The columnar cells became flat and pleomorphic but epithelial continuity was maintained. Goblet cells apparently decreased in number. Paneth cells, especially in the ileum, appreciably increased in size and number. During the recovery phase, the cystic crypts apparently re‐established continuity with the villus epithelium. Size and proportion of all epithelial cell types returned to normal. Scanning electron microscopy showed villus fusion and the cellular pleo‐morphism and loss of microvilli during the degenerative phase. During recovery of the villi some alteration in orientation and shape remained as shown by scanning electron

ISSN:0003-276X    

DOI:10.1002/ar.1091910102

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

年代:1978

数据来源: WILEY

摘要:

AbstractBrachymorphic(bm/bm)mice are disproportionately short in stature. Past biochemical studies on neonatal mice (Orkin et al., '76) demonstrated that epiphyseal cartilage from these mutants synthesizes glycosamino‐glycans (GAG) that are undersulfated. In this study, synthesis of GAG, as determined autoradiographically with Na235SO4and3H‐glucosamine was reduced in all areas ofbm/bmepiphyses both in vivo and in vitro as compared to normal C57BL/6J mice. Incorporation of both isotopic precursors into GAG of the brachymorphic proliferative zone was reduced to a greater extent than in the reserve zone. In addition, incorporation of these precursors into GAG of epiphyseal cartilages in vitro, as determined biochemically, was reduced by 40%. In contrast, the incorporation of3H‐leucine and3H‐proline into protein did not show differences between mutant and normal epiphyses. These results suggest that alterations in GAG synthesis inbm/bmepiphyseal growth plates are not exclusive to any one zone, but do appear to be most pronounced in the proliferati

ISSN:0003-276X    

DOI:10.1002/ar.1091910103

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

年代:1978

数据来源: WILEY

摘要:

AbstractProlactin is known to enhance the uptake and metabolism of testosterone in male accessory sex organs and to increase the weight of accessory sex organs from castrated rats over those from controls treated with testosterone alone. The present study was directed toward defining fine structural changes detectable with scanning and transmission electron microscopy which might accompany such responses. Accordingly, rat ventral prostrate gland was examined from castrated animals which had received testosterone propionate and ovine prolactin singly or together, or which had received vehicle only. Unoperated ani‐mals served as additional controls. Post‐castration glandular atrophy was not influenced by prolactin treatment alone. Testosterone restored epithelial height, secretory product, Golgi complexes and rough endoplasmic reticulum, such that cellular and tissue morphology was generally indistinguishable from that of unoperated controls. Prostatic tissue from animals given testosterone and prolactin simultaneously exhibited pleomorphic, cytoplasmic apical projections which extended into the acinar lumen. Transmission electron microscopy demonstrated that these blebs were devoid of organelles and microvilli; scanning electron microscopy revealed that the blebs were highly wrinkled and more numerous than were the projections observed in tissue from animals treated with testosterone alone, or in tissue from unoperated controls. It is suggested that such blebbing may reflect enhanced apocrine secretion in prolactin/testosterone stimulated restoration of the prostate gland in castrated r

ISSN:0003-276X    

DOI:10.1002/ar.1091910104

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

年代:1978

数据来源: WILEY

摘要:

AbstractBone marrow from adult rats fed a vitamin B6deficient diet for two weeks was found to have reduced numbers of neutrophils, erythroid cells and small lymphocytes. The numbers of transitional cells were not reduced. Since the small lymphocyte population in the bone marrow consists of B cells and null cells in approximately the same proportion, it was concluded that both cell types were reduced as a result of the deficiency. A complete recovery in the cellularity of the bone marrow was brought about by returning the vitamin B6deficient animals to a normal diet for four weeks. Other effects of the two‐week vitamin B6deficient diet included a failure to gain weight, a decrease in thymus weight and a reduction in the numbers of white blood cells in the peripheral blood. All of these defects were corrected after the animals had been fed a normal diet for four week

ISSN:0003-276X    

DOI:10.1002/ar.1091910105

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe intrahepatic distribution of nerves in the rat was studied using neurohistochemical and electron microscopic methods. Innervation was restricted primarily to vessels in the portal space and hilus. Both adrenergic and cholinergic fibers were observed in the adventitia of hepatic arteries, and to a lesser extent adjacent to portal veins. Some of the cholinergic fibers, however, were not contiguous with the vasculature. Near the hilus many of these fibers were associated with ganglia while peripherally some coursed into the immediately adjacent parenchyma where end bulbs abutted on hepatocytes. Ultrastructurally, scattered small nerves, devoid of neurolemma, were found contiguous with the portal lamina of hepatocytes. Nerve fibers deeper within the lobule were not seen but numerous gap junctions were observed between contiguous hepatocytes. Central and sublobular hepatic veins lacked innervation but adrenergic nerves were demonstrated in the walls of larger hepatic veins. Innervation of the biliary system was sparse. While nerves were interposed between vessels and bile ducts, such nerves tended to be associated more closely with the vasculature.

ISSN:0003-276X    

DOI:10.1002/ar.1091910106

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

年代:1978

数据来源: WILEY

摘要:

AbstractScanning and transmission electron microscopy have been used to investigate the structure of the papilla neglecta in the lizard,Anolis carolinensis.Situated in the posterior part of the utricle, the receptor is innervated by a branch of the posterior ampullary nerve and is covered by an extracellular membrane that exhibits a tapering extension into the orifice of the utriculo‐saccular duct. The neuroepithelium contains two populations of sensory cells within a matrix of sustentacular cells; one population (non‐calyceal hair cells) is supplied primarily by boutons and clublike terminals, while the other (calyceal hair cells) is served by calycine terminals that invest from one to five sensory cells. The apices of calyceal hair cells bulge into the utricular lumen and have larger diameters and ciliary counts than non‐calyceal cells, but other differences are not marked. Although the bases of calyceal hair cells are deeply indented by calyceal processes, both types show similar afferent synaptic structures confined to the nuclear and infranuclear regions. Efferent terminals synapse on afferent endings and hair cells in both cases; synapses directly on calyceal hair cells lie above the calyx, just beneath the apicolateral junctional complexes. Those complexes are basically similar throughout the receptor, except that a hemispheroidal gap junction between a supporting cell and adjacent hair cell was noted in several instances. Arrays of endoplasmic reticulum and specialized mitochondria occur adjacent to aggregations of afferent synaptic vesicles in both types of sensory cell; it is suggreted that such arrays may participate in the production of the vesicles in a process involving membrane recycling similar to that at the neuromuscular junction. Differences between calycine units and the type I hair cell of mammals are discussed, and evidence that suggests an equilibratory function for the lacertilian papilla neglecta is pres

ISSN:0003-276X    

DOI:10.1002/ar.1091910107

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

年代:1978

数据来源: WILEY

摘要:

AbstractDense crystalline deposits appeared within vacuoles in rat maturative ameloblasts as a result of repeated injections of sodium fluoride. The crystals assumed varied arrangements but were always observed within intracellular vacuoles. The crystals resemble those of normal enamel and resist microincineration. They are readily dissolved by decalcification and leave behind an organic framework which matches the outline of the crystals. An experimental model is presented which may be useful in further studies of calcium transport, enamel matrix absorption or digestion of cellular debris.

ISSN:0003-276X    

DOI:10.1002/ar.1091910108

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe rough endoplasmic reticulum (RER) ofXenopus laevishepatocytes was examined by freeze‐fracture and by conventional thin section electron microscopy. Much of the RER was present as stacks of cisternae at the cell periphery but, in addition, large whorls of cisternae were seen in the cytoplasm in most sections. Freeze‐fracture replicas revealed fenestrae in both stacked and whorled cisternae, although the fenestrae were more numerous in the whorls. The role of these fenestrae is unknown, but such structures would facilitate access of precursors to the protein synthetic machinery in this highly metabolically active cell type. This would be particularly important in RER whorls, where the innermost cisternae would otherwise be isolated from the rest of the cytopl

ISSN:0003-276X    

DOI:10.1002/ar.1091910109

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe thyroid gland of the C3H mouse is composed largely of the usual follicle but it also contains a second kind of follicle. To ascertain the embryologic origin of the cell types in each of these follicles, ventral pharyngeal outpocketings and ultimobranchial outpocketings were isolated (before they fused to form the thyroid gland) from the 12‐day‐old fetus of the C3H mouse. The outpocketings were implanted into different kidney capsules of adult C3H mice and were allowed to grow for several months. Transplants were then excised and examined by electron microscopy.The ventral contribution formed large aggregates of follicles and was recognized as a distinct bump on the surface of the kidney. It formed only typical thyroid epithelium arranged in follicles containing colloid. On the other hand, the ultimobranchial contribution usually formed only a small number of follicles, generally of small size. It was readily located because the follicles occurred next to a white plaque of bone or cartilage at the site of implantation. The ulti‐mobranchial contribution formed follicles containing four cell types: a ciliated cell, a cell with abundant agranular reticulum, a cell with many free ribosomes and fiber and occasional hemidesmosomes, and the C cell which was the most frequent cell type. No typical thyroid epithelium was observed in the ultimobran‐chial transplant.These observations suggest that the C cell in the usual follicle is derived from the ultimobranchial contribution, and that the second kind of follicle is largely an ultimobranchial contribution but the typical thyroid epithelium in it is largely or entirely a ventral contr

ISSN:0003-276X    

DOI:10.1002/ar.1091910110

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

年代:1978

数据来源: WILEY

摘要:

AbstractGuinea pig epididymal sperm, incubated for ATPases at pH 7.0 or pH 9.0, localize reaction product on both the periacrosomal segment of the plasmalemma and the outer acrosome membrane. In other species, e.g., rabbit, Ca++‐ATPase is identified with the outer acrosome membrane. It may transport Ca++into the acrosome for activation of enzymes released during the acrosome reaction. The neutral ATPase is demonstrable on the periacrosomal plasmalem‐ma and possibly modifies Ca++concentration in the fluid around the acrosome. In guinea pig sperm, Ca++‐ATPase is sensitive to centrifugation or washing of sperm which indicates that the ductal fluid has unusual properties for preservation of the acrosome. Inhibition of the enzyme by these treatments suggests that conditions on the plasmalemmal surface affect the acrosome membrane. Inability to separate reaction product on the plasmalemma from that on the acrosome membrane may be due to migration of reaction product across the periacrosomal space. However, the ATPases are elicited in the guinea pig under the same conditions as in other species. The pH 9.0 enzyme requires Ca++while the enzyme at pH 7.0 has no ion specificities. Demonstration of these enzymes indicates that mechanisms of acrosome activation, similar to those in other sperm, are relevant to the guine

ISSN:0003-276X    

DOI:10.1002/ar.1091910111

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

年代:1978

数据来源: WILEY