摘要:

AbstractRecent investigations have been aimed at understanding the ultrastructural‐functional relationships within the kidney at organ, tubule, subcellular, and molecular levels. This has led to a redefinition and more precise segmentation of the renal tubule. For example, the connecting piece between distal tubule and collecting system has now been established.The use of immunocytochemical techniques, such as fluorescence, ferritin‐ or peroxidase‐labelled immunoglobulin methods, has made it possible to identify proteins in the kidney especially in renal corpuscles. Two major noncollagenous glycoproteins, fibronectin and laminin, have now been identified in the glomerulus. The glycosaminoglycan, heparan sulfate, has been localized to the glomerular basement membrane and is thought to play an important role in charge perm‐selectivity during glomerular filtration. Subtle changes in glomerular podocyte or endothelial cell structure are postulated by some to play a role in the pathogenesis of acute renal failure. The role of the mesangial cell in glomerular function is being studied in situ in homogeneous cell populations. These cells are capable of prostaglandin production and can contract in response to hormonal stimulation.The intimate positioning of short‐ and long‐looped nephrons in the renal medulla and the unique nature of the pelvic epithelium correlates well with the purported role of urea recycling in the urinary concentrating mechanism. Determination of elemental concentration of soluble substances in various renal cell and extracellular compartments have been made using freeze‐hydrated and freeze‐dried cryosections of kidney tissue.The medullary and cortical ascending thick limbs of the distal tubule are morphologically and functionally distinct regions. Their response to hormonal stimulation and their enzymatic activities are quite different. Morphological studies of the collecting duct have provided new insight into the role this segment of the uriniferous tubule plays in fluid and electrolyte transport and urinar

ISSN:0003-276X    

DOI:10.1002/ar.1092050102

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

年代:1983

数据来源: WILEY

摘要:

AbstractTwo experiments were carried out with a total of 36 white‐footed mice (Peromyscus leucopus) exposed to either long (LP) or short (SP) photoperiod for six weeks. Ovaries and uteri were weighed. Serial sections of the ovaries were processed for light microscopy. The total number of the interstitial gland cells, preantral and antral follicles with early and advanced stages of atresia as well as corpora lutea, was determined.Uteri from LP mice weighed significantly more than those from SP mice in both experiments. In contrast, the weight of ovaries from LP and SP animals only differed significantly in one experiment; this experiment also produced no obvious changes in the total number of corpora lutea. While interstitial gland cells of LP ovaries were hypertrophic and appeared mature, the interstitial gland cells of SP ovaries were of the degenerating cell type. The total number of follicles as well as their mean follicular diameters were higher in LP animals in comparison with SP animals. In addition, the percentage of antral follicles were increased and there were fewer signs of advanced stages of atresia in the LP group. It is suggested that the changes of the interstitial gland cell morphology combined with alterations of follicular growth during LP or SP appear to support intensified follicular growt

ISSN:0003-276X    

DOI:10.1002/ar.1092050103

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe locomotion of human primordial germ cells (PGCs) in vitro was observed using 16‐mm time‐lapse microcinematography. PCGs dissociated from 5‐ to 6‐week human embryos were cultured in vitro using L‐15 medium and human cord serum, and their movement on three artificial and two natural substrates was compared. Three‐dimensional collagenous fiber nets reconstructed in the culure dish were found to be appropriate for PGC movement, although the cells did not migrate actively on any of the other substrates. The PGCs moved actively in an amoeboid fashion, extending pseudopodlike cytoplasmic processes toward the direction of movement. The direction of PGC locomotion was random. One PGC showed the most active motility; the velocity of the cell locomotion averaged 25 μm/h and it became extremely elongated, measuring 92 μm in its longer axis, whereas in the stationary state the PGC was rounded and measured 20 μm in diameter. Thus, the present study offers evidence that human PGCs can mi

ISSN:0003-276X    

DOI:10.1002/ar.1092050104

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of acid, basic, and organic extracts from Long Evans rat amniotic fluid (RAF) and from Swiss ICR mouse amniotic fluid (MAF) was studied on 15‐day fetal mouse duodenal mucosa in organ culture. Amniotic fluids (20 ml) were lyophilized and extracted (1) with CHCl3:MeOH and the organic phase was evaporated; then (2), the residue was acidified with a solution of 0.1 N HCl in 10% acetic acid and the liquid phase was lyophilized; finally (3), 0.01 M NH4OH was added to the residue and the liquid phase was lyophilized. The product of each extraction was added to 20 ml of Trowell T8 medium. Acid and basic extracts of RAF and MAF have no effect on the formation of duodenal villi and crypts after 48 hours of culture. With the organic extract of MAF, small villi are present after 48 hours of culture and absorptive cells are poorly differentiated. With the organic extract of RAF, well‐developed villi have differentiated after 48 hours of culture; moreover, crypts are present at the same stage and Paneth cells are identified within these crypts. During the 8–10 hour period, the explants cultured with the Trowell T8 medium supplemented with RAF or MAF organic extracts show a 35% increase in3H‐thymidine incorporation over the controls cultured with Trowell T8 medium alone. These results indicate that organic extracts from MAF and RAF are able to promote villus formation in undifferentiated explants from 15‐day fetal mouse duodenum in organ culture. Furthermore, RAF organic extract contains a factor that can induce the formation of duodenal crypts and the differentiation of Paneth cells in culture at least 2 days before their normal a

ISSN:0003-276X    

DOI:10.1002/ar.1092050105

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

年代:1983

数据来源: WILEY

摘要:

AbstractIncreased pulmonary artery pressures and decreased albumin concentrations were established in dogs, in vivo, by circulatory overload and by plasmapheresis. Each change, occurring singly, would be expected to produce an increase in outward filtration rate. The ultrastructure of the alveolar epithelium after the production of this presumed increase in filtration was evaluated by established morphometric techniques. The extent of extravascular fluid accumulation was assessed by multiple indicator‐dilution studies and by light microscopic analysis. Previous studies from this laboratory (DeFouw and Berendsen, 1979; DeFouw, 1980) define increased alveolar surface densities, increased type I cell vesiculation, and depleted type II cell lamellar body contents after increased filtration had induced septal edema and alveolar flooding in isolated perfused dog lungs. In the present study septal edema and alveolar flooding were not detected. Nor were changes observed in either alveolar epithelial cells or in alveolar configurations. However, there was significant accumulation of extravascular fluid in cuffs around extraalveolar vessels. These results are consistent with the interpretation that the initial stage of cardiodynamic edema formation, namely, peri‐vascular cuffing, is not associated with structural aberrations of the alveoli or their lining epithelial cells, in vivo. Since such changes were detected previously in isolated lungs after development of the final stages of edema, namely, septal fluid accumulation and alveolar flooding, additional studies of septal edema and alveolar flooding in intact animals are necessary to establish functional correlates to ultrastructural aberrations in severely edematous lu

ISSN:0003-276X    

DOI:10.1002/ar.1092050106

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe structure of the epidermis and hair‐follicle bulbs and the proliferative activities of their component cells were studied in the midside skin of male mice treated with epidermal growth factor (EGF) or saline during formation of the first coat (days 0–21). The epidermis was thickest at birth, but in control animals became progressively thinner as cell size and the number of layers of granular and cornified cells were reduced. EGF treatment from birth resulted in a thickening of the epidermis at 5 days of age, and at 5 and 8 days the histological appearance was strikingly similar to that on the day of birth. At 12 and 21 days the structure of the epidermis of EGF‐treated mice more closely resembled that of contemporaneous controls. The mitotic and labeling indices of the basal cells of control epidermis declined throughout the sampling period from peak values on the day of birth. By contrast, these indices were maintained at birth levels in EGF‐treated mice for 8 days before declining to approximate those of controls at 12 and 21 days.Hair growth rate was inhibited and hair diameter reduced in EGF‐treated mice (Moore et al., 1981a). These observations were reflected in changes in the follicle bulb. Both the growth of the bulb and the increase in numbers of bulb cells observed during the early part of the anagen phase were inhibited by EGF. However, neither the size of the dermal papilla nor the numbers of papilla cells were significantly altered in treated animals. The mitotic index of the bulb cell population declined during the sampling period in both experimental and control groups. However, the labeling index of bulb cells of EGF‐treated mice was significantly increased over contemporaneous control values on days 8 and 12. Rather than stimulating epidermal growth during the early postnatal period, these observations indicate that EGF delays the normal process of skin development by maintaining the proliferative and differentiation processes active in the cell populations at the time of birth. As a consequence of this, follicle development and hair growth ar

ISSN:0003-276X    

DOI:10.1002/ar.1092050107

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

年代:1983

数据来源: WILEY

摘要:

AbstractTwo morphological differences distinguish the membranes of the end bulb‐spherical cell synapse in rats and mice from those in guinea pigs and chinchillas. First, in freeze‐fracture replicas, the membranes of rat and mouse spherical cells lack perisynaptic aggregates which are present in the other species. Second, small gap junctions are present between the end bulb and spherical cell soma of rats and mice. These interspecies differences are not reflected in thin‐sectioned material. This observation points out the difficulty in attempting to generalize about the significance of intramembrane specializations in synaptic memb

ISSN:0003-276X    

DOI:10.1002/ar.1092050108

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

年代:1983

数据来源: WILEY

摘要:

AbstractGranule‐containing (GC) cells and related blood vessels in the superior cervical ganglion and the pelvic plexus of the rat were examined by light and electron microscopy of serial thin sections. In the superior cervical ganglion, GC cells formed many clusters of more than 20 cells. These clusters were supplied with dense networks of fenestrated capillaries, while the ordinary ganglion cells had continuous capillaries distributed more sparsely. Several continuous capillaries diverged from the networks in the GC cell clusters to join with capillaries around the ganglion cells. In the pelvic plexus, continuous capillaries with well‐developed pericytes were distributed similarly around the GC cells and the ganglion cells. Dense networks of fenestrated capillaries in the clusters were never seen. Based on these observations, the physiological significance of the GC cells was discus

ISSN:0003-276X    

DOI:10.1002/ar.1092050109

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe caudal‐most regenerated spinal cord inSternarchus albifronsconsists solely of an ependymal tube. Ependymal cells are enlarged radially and are more numerous than in unregenerated cord. Projections of ependymal cell cytoplasm and Reissner's fiber fill most of the central canal. Small groups of neurites and cell processes filled with dense‐cored vesicles lie between abluminal processes of ependymal cells.Rostral to this, additional cells appear dorsal and lateral to the inner ependymal layer. Some cell bodies contain numerous dense‐cored vesicles. Larger bundles of neurites, some with synapses, are present. Invaginations of the peripheral edge of the cord create enclosed spaces lined with basal lamina. In the peripheral region, longitudinally oriented neurites extend through extracellular spaces or channels. The ventral portion at some levels of regenerated cord is completely filled with neurites, processes containing dense‐cored vesicles, and capillaries. Similar masses of neurites and processes containing dense‐cored vesicles lie outside the cord proper, in or near the meningeal layer.In rostral‐most sections, the organization of regenerated spinal cord approaches that of normal cord, with the regenerated cord exhibiting groups of myelinated axons, differentiated fibrous astrocytes and oligodendroglia, cell bodies containing dense‐cored vesicles, and differentiated electromotor neurons. These observations indicate a degree of pluripotency in some of the ependymal cells in adultSternarchus. Moreover, they are consistent with a role of ependymal cells in the guidance of regenera

ISSN:0003-276X    

DOI:10.1002/ar.1092050110

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe morphology of spinal cord in the caudal‐most spinal segments of normal adultSternarchus albifronsis different from that of more rostral adult cord. The caudal segments are strikingly similar to the regenerating spinal cord observed after amputation of the tail inSternarchus. In the caudal‐most vertebral segment of normal spinal cord, ependymal cells are radially enlarged and are more numerous than in more rostral adult cord. Large processes of the ependymal cells extend into the central canal, which also contains a prominent Reissner's fiber. Invaginations of the outer surface of the spinal cord, with the associated basal lamina, are common. Lateral to the immediate ependymal layer, extracellular spaces contain longitudinally oriented neurites. Cell bodies and cell processes filled with dense‐cored vesicles occur throughout the caudal‐most segment of spinal cord, and are especially concentrated in the ventral half, interspersed with numerous capillaries. In all these respects the caudal‐most segments of normal adult spinal cord inSternarchusclosely resemble regenerating spinal cord ofSternarchus. In both regions, at least some of the ependymal cells retain the ability to divide and generate new neurons and gl

ISSN:0003-276X    

DOI:10.1002/ar.1092050111

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

年代:1983

数据来源: WILEY