摘要:

AbstractUterine events during pregnancy were examined histologically in laboratorybred black mastiff bats (Molossus ater) as part of an effort to develop this species as a model for studies of the factors controlling trophoblastic growth.Embryos entered the uterus at the morula stage and in most cases shed their zonae pellucidae reasonably intact, apparently as blastocyst expansion occurred. Implantation was superficial and observed to occur only in the right uterine horn. During implantation the trophoblast was brought into apposition to the endometrium by both blastocyst expansion and closure of the uterine lumen. A decidual reaction was evident at an early stage of uterine epithelial displacement and spread rapidly through the endometrium. Initial trophoblastic proliferation occurred along the uterine lumen and into the glands, while its invasion of the endometrial stroma was delayed.Although one or several primordial cavities have been observed to develop within the epiblast during implantation, these subsequently opened to a trophoepiblastic cavity, and the definitive amnion was formed by folding.A choriovitelline placenta was present briefly at the somite stage, but disappeared as the exocoelom enlarged and the yolk sac collapsed. The latter persisted through pregnancy, however, as a glandular‐appearing body. As the yolk sac retracted from the chorion, it was replaced by allantoic mesoderm, creating a diffuse labyrinthine endotheliodichorial placenta. This was prominent during mid‐gestation, but was supplanted by the discoidal hemochorial placenta as the major site of feto‐maternal exchange during late preg

ISSN:0002-9106    

DOI:10.1002/aja.1001870202

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

年代:1990

数据来源: WILEY

摘要:

AbstractEmbryonic development of the Chinese hamster (Cricetulus griseus) was studied from the onset of implantation to the formation of the parietal yolk sac placenta. Implantation began on day 6 of pregnancy, when the embryo became fixed to the uterine luminal epithelium. At this time there was no zona pellucida, and microvilli of the trophoblast and uterine epithelium were closely apposed. Stromal cells immediately adjacent to the implantation chamber began to enlarge and accumulate glycogen. By day 7 the mural trophoblast penetrated the luminal epithelium in discrete areas. The trophoblast appeared to phagocytize uterine epithelial cells, although epithelium adjoining the points of penetration was normal. In other areas nascent apical protrusions from the uterine epithelium indented the surface of the trophoblast. The epiblast had enlarged and both visceral and parietal endoderm cells were present. The well‐developed decidual cells were epithelioid and completely surrounded the implantation chamber. On day 8 the uterine epithelium had disappeared along the mural surface of the embryo. The embryonic cell mass was elongated and filled the yolk sac cavity. Reichert's membrane was well developed. The uterine epithelial basal lamina was largely disrupted, and the trophoblast was in direct contact with decidual cells. Primary and secondary giant trophoblast cells were present and in contact with extravasated maternal blood. The mural trophoblast formed channels in which blood cells were found in close proximity to Reichert's membrane. Decidual cells were in contact with capillary epithelium and in some cases formed part of the vessel wall. Structural changes occurring in the embryo and endometrium during implantation in the Chinese hamster are described for the first time in this report and are compared to those described for some other myomorph rodent

ISSN:0002-9106    

DOI:10.1002/aja.1001870203

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

年代:1990

数据来源: WILEY

摘要:

AbstractTransverse sections of the ulnar, saphenous, and sural nerves taken at specific levels in normal, young‐adult beagle dogs were examined qualitatively and quantitatively at both the light and electron microscopic levels. The aim of this investigation was to provide baseline information for future studies of peripheral nervedisease in this species. A systematic sampling technique was used for the determination of nerve components (i.e., unmyelinated axons and Schwann cell and fibroblast nuclei). In all nerves sampled, the average size distribution for unmyelinated axons was unimodal, and most of the axons were 0.4–1.1 μm in diameter. Within this range, there were slight individual and nerve‐to‐nerve variations in the location of the largest diameter peak. The mean densities of Schwann cell nuclei (numbers/mm2) ranged from 841/mm2in the palmar branch of the ulnar nerve, to 1,223/mm2in the caudal cutaneous sural nerve, being nearly four times the average density or fibroblast nuclei.In every animal and in almost every nerve, a few abnormalities were found; and these should be kept in mind when assessing peripheral nerves in

ISSN:0002-9106    

DOI:10.1002/aja.1001870204

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe distribution of two novel human, basement‐membrane (BM) collagens has been characterized by immunohistochemical analysis of developing and mature tissue using monoclonal antibodies specific for the non‐collagenous (NC1) domain of each molecule. A distribution more restricted than that of type IV collagen was observed. In the kidney, the 28K parent molecules appear relatively late, at the early capillary‐loop stage of glomerular development, whereas type IV collagen is present in all BM, including those of the ureteric bud, S‐form, primitive glomerulus, and vessels. Antibody to the Alport familial nephritis antigen (a 26K peptide), which is missing from epidermal BM and glomerular BM in Alport syndrome, reacted with the ureteral bud BM and all stages of glomerular BM development from the early capillary‐loop stage onward, but not with BM of more primitive glomeruli (vesicles and S forms).In the human fetal eye, the collagen molecules from which the 28K NC1 peptides are derived appear later in development than type IV collagen. They are present in trace amounts in Bruch's membrane but are not detected until after birth in the retinal internal limiting membrane and cuticular and non‐pigmented epithelial BM of the ciliary process. In contrast, the BM of the lens capsule and Descemet's membrane were reactive with anti‐28K antibodies early in development. In all instances, the 28K peptides are detected in BM that also contain the Alport antigen, although the latter is present in some BM not containing the 28K peptides. The distribution of Alport antigen and type IV collagen in developing eye is similar to that observed in the mature eye. The 28K parent molecules appear to be expressed in concert with the maturation of the BM, coincident with fusion of glomerular endothelial and epithelial BM, whereas the lens capsule BM and Descemet's membrane contain these restricted components much earlier

ISSN:0002-9106    

DOI:10.1002/aja.1001870205

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

年代:1990

数据来源: WILEY

摘要:

AbstractTo examine variations in immunoreactivity of angiotensinogen and cathepsins B and H in hepatocytes over 24 hr, rat liver was examined immunohistochemically. Immunoreactivity of angiotensinogen and cathepsins B and H in periportal and perivenous hepatocytes varied significantly over 24 hr, when analyzed by an image analyzer. In periportal and perivenous hepatocytes, immunoreactivity of angiotensinogen was highest at 0800 hr and lowest at 2000 hr or 0000 hr, whereas that of cathepsins B and H was maximal at 1600 hr and minimal at 0400 hr or 0800 hr. Proteolytic activities of cathepsins B and H in liver extracts varied in parallel to the variations in immunoreactivity of these enzymes. Localization of angiotensinogen in the liver acinus was inversely correlated to that of cathepsins B and H; angiotensinogen was predominantly localized in periportal hepatocytes, but cathepsins B and H were in perivenous hepatocytes at each time point examined. These results suggest that angiotensinogen in hepatocytes is actively synthesized and secreted early in the light period, whereas proteolytic activities in lysosomes of hepatocytes are augmented late in the light period.

ISSN:0002-9106    

DOI:10.1002/aja.1001870206

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe have determined the kinetics of endoplasmic reticulum (ER) reconstitution following insertion of rat‐liver smooth microsomes (SM) intoXenopusoocyte cytoplasm using electron microscopy as well as cytochemistry and thick‐section 3‐dimensional reconstruction. Oocytes were fixed 0, 10, 20, 40, 80, and 120 min after microinjection with SM and processed for thin‐ and thick‐section electron microscopy. At 0 min postinjection, rat liver SM were observed as small vesicles and were loosely dispersed amongst oocyte organelles. At 10 min, tubules were discerned among many elongate vesicles; and these structures comprised large cytoplasmic regions delimited by mitochondria and yolk platelets. By 20 min, segregation of transplanted organelles yielded yolk‐platelet‐free regions composed of few vesicles but increasingly numerous, long and anastomosing tubules. By 40 min, a network with numerous tubular branches and fenestrations was observed among the few remaining vesicles. By 80 min, transformation of rat liver SM into a complex network of branching and anastomosing tubules was complete. Three‐dimensional reconstruction revealed the network to be composed of interconnecting elements consisting of anastomosing tubules. The reconstituted network of anastomosing tubules inXenopusoocytes was compared to the network of anastomosing tubules in rat liver hepatocytes and was found to be essentially identical. Network formation occurred in oocytes pretreated with either vinblastine (40 μM) or nocodazole (0.166 μM), and network organization was maintained in oocytes treated with the same drugs after microinjection and reconstitution. We conclude that SM retain sufficient molecular information for rapid self‐assembly into structures resembling those in the cells from which they were derived. Both the assembly and maintenance of ER structure in oocyte cytoplasm are microtubule‐independent. The formation of such structures following microinjection of SM into living cells provides a unique assay for this type of

ISSN:0002-9106    

DOI:10.1002/aja.1001870207

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

年代:1990

数据来源: WILEY

摘要:

AbstractIn this series of studies, the innervation patterns of whole‐mount preparation of bicuspid and tricuspid valves were studied by light microscopy in the mouse, rat, guinea pig, and opossum. The acetylcholinesterase‐positive networks of nerve fibers showed many similarities in the basic patterns of valve innervation in all of the species studied, but several interspecies variations were observed. The basal zone of the valve adjacent to the fibromuscular atrioventricular ring displayed the most dense plexus of nerves, with acetylcholinesterase‐positive fibers being seen across the width of the valve. In the intermediate zone of the valve, less dense plexuses of nerve fibers were found; and these were more numerous in the cuspal areas and less numerous in the intervening commissural areas. In the distal portions of the valve, nerve networks arborized extensively, with some of their nerve fibers extending toward the chordae tendineae and the free edges of the valve cusps. Only in the guinea pig and opossum did these fibers reach the free margin of the valve cusp, where they either ended directly as free nerve endings or lay parallel to the free edge of the cusp, often running between adjacent chordae tendineae. Although the patterns of innervation were similar in both bicuspid and tricuspid valves, the innervation density of the bicuspid valve was greater than that of the tricuspid valve for each species examined.A distinguishing feature of guinea pig and opossum tricuspid valves was that their chordae tendineae were relatively more prominent and more densely innervated than the bicuspid chordae tendineae. Free nerve endings with no light microscopic evidence of specialization were present throughout the bicuspid and tricuspid valves of all species studied. Some nerve endings in the opossum showed evidence of specialization, with brush‐like arborizations leading to presumed free terminals seen chiefly in the distal zone of the valve cusps. Although some general tendencies were apparent, we have demonstrated that interspecies heterogeneity exists in the terminal networks of the atrioventricular valves of mouse, rat, guinea pig, and opposum.In spite of the questions raised regarding the significance of valve innervation in light of the success of valve prostheses, there is relatively high morbidity and mortality associated with heart valve replacement, partly due to deterioration in ventricular function. We and other investigators have reported that valvar nerves extend to the chordae and papillary muscles, varying with valve and species.This anatomical information about normal valves helps to lay the foundation for future studies of the role of valve innervation in the regulation of cardiac function and dysfunction. Such knowledge should be applicable for the control and management of myocardial infarction, valve disease, valve replacement, valvuloplasty, cardiac transplantation, administration of dru

ISSN:0002-9106    

DOI:10.1002/aja.1001870208

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

年代:1990

数据来源: WILEY

摘要:

AbstractArterial networks in 50 pairs of human fetal hands, made visible by perfusion with radiopaque media, were compared between right and left hands. The imaged primary arterial networks in the fetal hands were also compared with those in adult human and rhesus monkey hands. It was found that superficial arch configurations and their primary ramifications are bilaterally similar in human fetal hands. The configurations of the primary arterial networks are established very early in prenatal growth and may be maintained into adulthood. The similarities in the arterial network arrangements between fetal human and rhesus monkey hands suggest that the rhesus monkey hand could provide and appropriate model for studies of surgical neurovascular anastomosis.

ISSN:0002-9106    

DOI:10.1002/aja.1001870209

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

年代:1990

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001870210

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

年代:1990

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001870201

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

年代:1990

数据来源: WILEY