摘要:

AbstractThe ultrastructure of cardiac muscle from dystrophic mice was compared with that of their non‐dystrophic littermates. Among the abnormalities observed in the fine structure of the muscle fibers in the dystrophic animals were increased lipid, swollen mitochondria, swollen tubules of the sarcoplasmic reticulum, supercontracted myofibrils, and partially separated intercalated discs. The ventricular muscle appeared to be the region most often affected; in only one of eleven animals did the atrium show discernible effects of the dystrophy. Although a progression of degenerative events seemed to occur, a time schedule could not be determined because of the large variation among hearts of dystrophic animals. The ultrastructure of the hearts from non‐dystrophic littermates was normal. It appears that the depressed cardiac function caused by the myopathy may play a major role in the early death of the dystrophic mice, as in the case of dystrophic hamsters and men. Most of the ultrastructural abnormalities observed could be accounted for if there were an elevation of intracellular free Ca++concentrat

ISSN:0002-9106    

DOI:10.1002/aja.1001340302

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

年代:1972

数据来源: WILEY

摘要:

AbstractSerial sections of 36 embryos aged six to eight postovulatory weeks (12 to 31 mm C. R. length) were examined. The clavicle and the mandible began to ossify during stage 18, 19, or 20, the clavicle (at least frequently) by means of two centers. The maxilla followed rapidly (stages 19, 20). The premaxilla was in continuity with the maxilla proper, either as a mesenchymal condensation or as an ossific area (stages 20, 21). The next elements to commence ossification were the humerus (stages 21, 22), the radius (stages 21, 23), and the femur, tibia, and ulna (stages 22, 23). By stage 23 the following were also undergoing ossification in at least some cases: interparietal, supra‐occipital, anterior process of the malleus, the squamous temporal, palatine, medial pterygoid plate, zygomatic, frontal, vomer, scapula, and distal phalanges of the hand. Cellular invasion was found in the clavicle and in the bone collars of the radius, ulna, and femur at eight postovulatory weeks. The cartilages of the first pharyngeal arches (chondrifying at stages 18, 19) approached the median plane (stage 20) but did not fuse in the embryonic period proper; their cartilaginous tissue underwent localized hypertrophy by stage 23, but endochondral ossification did not occur until the fetal perio

ISSN:0002-9106    

DOI:10.1002/aja.1001340303

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

年代:1972

数据来源: WILEY

摘要:

AbstractEarly gerbil development was studied from days 4 through 12 of gestation. Implantation occurs on day 8 in a shallow antimesometrial implantation crypt. The proamniotic cavity forms from an invagination of basal trophoblast and a folding together of the rim of the cup thus produced. The approximation of this rim gives rise to the ectoplacental cone. The further development and expansion of the ectoplacental cone is much like the rat. Amniogenesis is by folding into the proamniotic cavity. Between large glycogen‐filled decidual cells occur many PAS‐positive eosinophilic granular cells. A massive subplacental gland forms from proliferating uterine epithelium within the decidua basalis. Epithelial proliferation begins shortly after implantation, and soon short thick cellular processes extend from the antimesometrial side of the lumen whereas long branching cords penetrate the decidua basalis mesometrially. The function of this structure is unkn

ISSN:0002-9106    

DOI:10.1002/aja.1001340304

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

年代:1972

数据来源: WILEY

摘要:

AbstractPlacental development was studied in 24 gerbils from day 13 to term. Allantoic mesoderm contacts and vascularizes the chorionic‐trager plate of germinal cytotrophoblast on day 13. Soon villous extensions penetrate the plate, carrying with them a covering of three layers of trophoblast derived from it. As the villi elongate, clumps of germinal cytotrophoblast are carried peripherally by them. Further development of each villus results in a cylindrical mesenchymal core with a central arteriole, and radially arranged branching lamellar extensions carrying capillaries derived from the villus arteriole. Germinal cytotrophblast clusters disappear near term, but some indication always remains of the trilaminar covering of the villus and its lamellae. A typical countercurrent blood flow pattern occurs. The trophospongium is derived from the ectoplacental cone and the mesometrial surface of the germinal cytotrophoblastic plate. Although a few clusters of small cells occur, it is essentially a giant cell trophospongium and never contains cells resembling the clear cells of the rat. Late in pregnancy it becomes much reduced in thickness. The unique subplacental gland begins to degenerate soon after placental establishment and is gone by the last half of pregnancy. The metrial gland begins development at midterm and becomes a solid mass of cells filling the perivascular space of the mesometrial triangle at ter

ISSN:0002-9106    

DOI:10.1002/aja.1001340305

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe development of thoracic sympathetic ganglia was studied in rabbit fetuses at 14 to 30 days of gestation by light, electron, and fluorescence microscopy. Changes that occurred during the development of sympathetic neurons, supporting cells, and granule‐containing cells are described and the following conclusions drawn. (1) Sympathetic neurons and granule‐containing cells arise from a common “indifferent cell” precursor. (2) Monoamine fluorescence (a manifestation of the presence of catecholamines) appears early in the development of sympathetic neuroblasts. (3) The development of neuroblasts in a sympathetic ganglion is asynchronous; i.e., each neuroblast develops at its own rate, irrespective of the rate of development of its sister cells. (4) Granule‐containing and catecholamine‐storing cells develop rapidly and probably become potentially functional early in the life of the fetus, as inferred from the abundance of dense‐core vesicles and intense monoamine fluorescence. (5) The derivation of supporting cells (“satellite” and Schwann cells) could not be determined. They had differentiated into an easily recognizable cell form in the youngest specimens studied, and appeared to be enveloping cell bodies (as satellite cells) or axons (as Schwann cells)

ISSN:0002-9106    

DOI:10.1002/aja.1001340306

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe permeability of the guinea pig parietal yolk sac placenta late in gestation was investigated by means of electron microscopy using the tracer proteins ferritin and peroxidase. The parietal yolk sac consists of a layer of trophoblast, a thick extracellular lamina (Reichert's membrane) and a layer of endoderm. After injection into the maternal vascular system, the proteins crossed the trophoblast by means of small pinocytotic vesicles. Both proteins readily permeated Reichert's membrane and then moved by an intercellular pathway between endoderm cells to reach the uterine lumen. After injection of ferritin into the uterine lumen, the protein was observed between endoderm cells and throughout Reichert's membrane. Presumably the marked permeability of the endodermal epithelium to the tracer molecules is due to the absence ofzonulae occludentesaround the endoderm cells. Parietal endoderm cells exhibited limited pinocytotic activity regardless of the site of injection. The results indicate that the parietal yolk sac placenta of the guinea pig is permeable to relatively large molecules and therefore it may be an important pathway in overall maternal‐fetal exchange in this specie

ISSN:0002-9106    

DOI:10.1002/aja.1001340307

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

年代:1972

数据来源: WILEY

摘要:

AbstractStructural changes in secretory units of developing canine salivary glands have been correlated with their histochemically demonstrable carbohydrate content. At birth, three and eight weeks, and six months, secretory cells and duct systems of parotid, submandibular, sublingual and zygomatic glands of mongrel puppies were examined for morphology and localization of sulfomucin, sialomucin, neutral polysaccharide and glycogen. Combining structural and histochemical criteria a classification was formulated to discriminate between mucous, serous, and seromucous cells. Within the first six months of life changes occur in the proportion of these cells in individual salivary glands. Structurally distinct typical and atypical mucous cells contained acidic carbohydrates, usually sulfomucin. In sublingual glands of more mature dogs, however, sialomucin was the predominant constituent in atypical mucous cells. Serous acinar cells containing neutral polysaccharide occurred only in these glands. Seromucous acinar cells secreting acidic carbohydrates, usually sialomucins, were recognized in parotid and zygomatic glands. Demilunes composed of sialomucin‐producing seromucous cells and neutral polysaccharide‐producing serous cells were observed in submandibular and zygomatic glands, respectively. From this investigation it appears that the structural and carbohydrate profile of developing canine salivary glands is distinctive to the particular age exami

ISSN:0002-9106    

DOI:10.1002/aja.1001340308

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

年代:1972

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001340301

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

年代:1972

数据来源: WILEY