摘要:

AbstractNormal development of the mouse embryonic heart was studied at the organ level using microdissection and scanning electron microscopy (SEM). Altogether 225 embryos, sampled at 8‐hour intervals between 11ed (ed = embryonic day; day of vaginal plug = led) and 15ed were collected. Their hearts were fixed by high flow‐low pressure perfusion, micro‐dissected, and observed in SEM. Standardized frontal, right profile, and left profile SEM micrographs were obtained and analyzed.The main purpose of this study was to create a series of normal stages of mouse cardiac development as a reference for ongoing studies in experimental cardiac teratology (e.g., in fetal mouse trisomies). Comparisons with chick, human, and dog embryonic hearts, prepared using the same technique, show that the mouse embryonic heart is characterized by a relatively deep interventricular sulcus. The absence of a conoventricular sulcus in the mouse results in poor definition of the boundary between the conus and the right ventricle. The external separation of the aorta and the pulmonary artery is evident from 13ed onward. The respective positions of the great arteries (aorta dextroposterior, pulmonary artery sinistroanterior) does not change until the end of cardiac organogenesis (15ed in the m

ISSN:0002-9106    

DOI:10.1002/aja.1001840202

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

年代:1989

数据来源: WILEY

摘要:

AbstractNormal stages of intracardiac development of the mouse heart are illustrated by a collection and analysis of two complementary SEM views, the septal and parietal halves of the right ventricle and conotruncus. These views are particularly suitable for understanding the septation of the outflow tract of the heart. They represent references for the studies of the pathogenesis of conotruncal malformations. The analysis is based on 90 hearts between 11ed and 15ed at intervals of 8 hours with an additional stage at 16ed. They were prepared by perfusion fixation, microdissection, and critical point drying and were examined in SEM. The following main features of the intracardiac morphogenesis were observed: (1) the presence of two spirally positioned conotruncal ridges, their disto‐proximal fusion, and the formation of the semilunar valves at their distal part; (2) the trabecular transformation of the conotruncal wall; and (3) the presence of two different interventricular foramina (FIV II and FIV III), with the final closure of FIV III at 14edl6h‐15ed.As a result of these observations, our description of the outflow tract septation and its interpretation are different from other conceptions based on mechanisms such as bulbar shift, bulbar absorption, torsions, or transfer of the aorta into the left ventri

ISSN:0002-9106    

DOI:10.1002/aja.1001840203

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

年代:1989

数据来源: WILEY

摘要:

AbstractEpicardial formation in the embryonic chick heart from initial to final stages was revealed by means of computer‐aided reconstructions based on serial resin sections for light microscopy, with further detailed observations using scanning and transmission electron microscopy. The origin of the epicardium was recognized as protrusions of mesothelial cell clusters on the right side of the external surface of the sinus venosus at 23 somites (stage 14+). These protrusions elongated to give rise to several villous processes, the tips of which eventually touched the dorsal wall of the embryonic heart at 30 somites (stage 17). Originating from these adhesion sites, mesothelial cells spread gradually onto myocardial cells in all directions to form a monolayered sheetlike cover. Thus, by stage 23, the ventricle was completely overlaid with epicardium, and blood‐island‐like structures appeared within the subepicardial layer. The atrium was not enveloped by epicardium until stage 25, and the extreme distal end of the bulbus cordis was reached by the advancing epicardium at stage 27. A chronological table of epicardial formation in the chick heart is pres

ISSN:0002-9106    

DOI:10.1002/aja.1001840204

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe subpopulations of lymphocytes and non‐lymphoid cells in high endothelial venules (HEV) and in lymphatic capillaries surrounding lymphoid follicles in bronchus‐associated lymphoid tissue (BALT) were examined by electron microscopy after preembedding the tissue and staining with an immunoperoxidase technique. The results were compared with those obtained in gut‐associated lymphoid tissue (GALT) reported previously. Monoclonal mouse‐anti‐rat T cell, IgG, IgM, IgA, and Ia antisera were used. Plasma cells that were reactive to anti‐IgG, anti‐IgM, and anti‐IgA were detected as cells in which the 3′, 3′ ‐diaminobenzidine tetrahydroxychloride reaction product was localized in rough endoplasmic reticulum and perinuclear spaces but not on plasma membranes. These plasma cells did not occur in either lymphatic capillaries or HEV in BALT as they did in GALT. Cells with surface Ig (sIg cells), T‐cell antigen (T cells), and Ia antigen (Ia cells) were present in BALT. T cells were located predominantly in the follicular area opposite the bronchial epithelium; IgM‐ and IgG‐reactive cells were found in the follicular area adjacent to the bronchial epithelium; and IgA‐positive cells were found in the lateral part of the area where the T cells were localized (T‐cell area). Ia cells were abundant throughout BALT and in moderate numbers in the epithelium. A striking observation was the presence of “nurse‐cell”‐like structures in the periphery of BALT. The percentages of T, sIgG, sIgM, and sIgA cells in the HEV were 54.7%, 2.4%, 28.9%, and 27.3%, respectively, and in the lymphatic capillaries, 41.2%, 3.8%, 38.2%, and 21.2%, respectively. Non‐lymphoid cells with Ia antigen, presumably interdigitating cells (IDC), were often seen in the two types of vessels. The percentage was 4. 3% in the HEV and 5.6% in the lymphatic capillaries. The results indicate that the largest common lymphocyte subpopulation in the two types of vessels surrounding follicles in BALT is T cells, followed by sIgM or sIgA cells as seen in GALT; IDC may be on

ISSN:0002-9106    

DOI:10.1002/aja.1001840205

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

年代:1989

数据来源: WILEY

摘要:

AbstractCells of the granular convoluted tubules (GCTs) of the submandibular glands of senescent male mice show structural changes indicative of functional decline. In order to define the nature of these age‐related changes more clearly, the fine structure of GCT cells of 12‐ and 28‐month‐old males was compared. In old mice, there was cell‐to‐cell variation in the extent of these changes, with some cells of senescent males appearing no different from those of young adults. In affected cells the most striking alterations were seen in secretion granules and lysosomal elements. Secretion granules varied greatly in size, with some GCT cells having only very fine apical granules. Secondary lysosomes and large lipofuscin granules were frequent in the basal cytoplasm. Very large dense bodies (3‐5 μm) occurred in many cells. These possibly represent intracellular pools of released secretory materials, as they were occasionally seen in continuity with the luminal contents. Structures whose appearance was intermediate between the very large dense bodies and lipofuscin granules were common, suggesting crinophagic activity. There was an apparent decrease in numbers of polysomes and in the extent of the Golgi apparatus. These fine structural changes are consistent with impairments with advanced age in synthesis and posttranslational processing of secretory products by affected GCT cells. In addition to cell‐to‐cell variation in any one male, there was also interanimal variation in the degree and extent of these

ISSN:0002-9106    

DOI:10.1002/aja.1001840206

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

年代:1989

数据来源: WILEY

摘要:

AbstractLangerhans cells (LCs) positive for HLA‐DR antigens were present in developing human epidermis by at least 7 weeks estimated gestational age (EGA). Most were negative for CD1 (T6) until 12‐13 weeks EGA when they underwent a dramatic increase in CD1 reactivity. To gain insight into the density of LCs during ontogeny and to assess whether their distribution was coordinated with epidermal growth, the number of cells positive for both HLA‐DR and CD1 antigens was determined relative to surface area and to volume of developing, interfollicular epidermis. LCs differed in their phenotype, distribution (follicular vs. interfollicular), size, and shape between 7 and 21 weeks EGA; however, during this period they maintained a statistically equivalent (P>.25) density (65 cells/mm2and 1,750/mm3) even though the epidermis increased in thickness and the fetus rapidly expanded its surface area. While LCs were evenly distributed within the epidermal sheets at all gestational ages, those in embryonic skin were much smaller and less dendritic than the older cells. The density, size, and shape of LCs in developing skin seemed to be independent of epidermal status (e.g., thickness, stage of keratinization, and number of cell layers) but rather were correlated with gestational age. The number of fetal LCs, through at least 23 weeks EGA, was only 10‐20% of the adult LC density. Thus, we can conclude that the increase in LC density to adult levels must occur either during the third trimester or afte

ISSN:0002-9106    

DOI:10.1002/aja.1001840207

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe areas of the femoral origin of the cruciate ligaments have approximately the shape of sectors of ellipses, the one for the anterior ligament on the lateral condyle posteroproximally and the one for the posterior ligament on the medial condyle distally. By means of a new technique of dissection, combined with the use of X‐rays, the change in distance between the origin and insertion and so the change of tension of single bundles of the ligaments could be analyzed. Only a rather thin bundle in each cruciate ligament is in constant tension: “guiding bundles.” The maximal diminution of distance between the origin and insertion for some bundles is 65%. In the anterior cruciate ligament the majority of fibers are taut in extreme extension: “limiting bundles.” The same is true in the posterior cruciate ligament in extreme flexion. There are also some fibers, especially in the posterior cruciate ligament, that are taut only in an intermediate position. The geometric analysis of the function of different groups of fibers was performed by a modification of Menschik's concept of a four

ISSN:0002-9106    

DOI:10.1002/aja.1001840208

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

年代:1989

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001840201

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

年代:1989

数据来源: WILEY