摘要:

AbstractRhodamine‐conjugated phalloidin staining was used to study the distribution of filamentous actin in the developing heart of embryonic chicks and rats during the morphogenetic period of cardiac septation. In the chick, intense fluorescence indicative of abundant filamentous actin was observed along the myocardium and in the mesenchymal condensations that formed within the aorticopulmonary septum at day 5. Such cellular condensations and concentration of filamentous actin were not seen in the atrioventricular cushions nor in the preseptation outflow tract. Similar results were found in the 14‐day rat embryo. In electron micrographs, microfilament bundles with irregular dense bodies were seen in elongated mesenchymal cells between the valve sites of both species. Cell‐cell contacts were observed between such elongated cells and myocyte processes protruding from the nearby myocardial sheath. These histochemical and ultrastructural observations suggest that such mesenchymal condensations serve a specialized mechanical tensile role during embryonic septation of cardiac outflow cha

ISSN:0003-276X    

DOI:10.1002/ar.1092230112

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

年代:1989

数据来源: WILEY

摘要:

AbstractAntibodies specific for fibronectin were utilized to determine the sites of localization in the liver during development. The livers of fetal rats from each of gestation days 11‐19, and from days 1 and 8 postpartum, were studied by fluorescence microscopy. Fibronectin was localized predominatly in megakaryocytes and megakaryocyte precursors, and to a lesser extent in the extracellular matrix surrounding blood vessels and between hepatocytes and sinusoids. The cytoplasm of megakaryocytes and their precursors displayed bright fluorescence but their nuclei were negative for fibronectin. Hepatocytes had negative or faint fluorescence. Megakaryocytes were present in the liver from day 12, and were numerous from day 13 through most of the rest of gestation. The relative numbers of megakaryocytes decreased in later gestation; at 8 days postpartum only a few were observed per section. Hepatic megakaryocytes appeared before megakaryocytes were established in spleen and bone marrow. The early and persistent high levels of fibronectin in hepatic megakaryocytes, in the absence of comparable localization within hepatocytes, leads us to the hypothesis that megakaryocytes are important in establishing circulating fibronectin levels in the fetus. Similarly, bone marrow megakaryocytes may contribute to circulating fibronectin in the adul

ISSN:0003-276X    

DOI:10.1002/ar.1092230113

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe Ruffini endings and associated cells in the periodontal ligament of rat incisors were investigated by means of immunohistochemistry for glia‐specific S‐100 protein and electron microscopy. Numerous Ruffini endings, which were immunoreactive for S‐100 protein as well as for neurofilament protein, were distributed in the alveolus‐related part of the lingual periodontal ligament. In electron microscopy, the Ruffini endings displayed expanded axoplasmic spines filled with a large number of mitochondria and neurofilaments; some of the spines directly contacted the surrounding collagen fibers via fingerlike projections. The axoplasmic spines and Schwann sheath, for the most part, were covered alternately by single or multiple layers of the basal lamina.Several rounded cells showing S‐100 immunoreactivity occurred in the vicinity of the Ruffini endings. The rounded cells associated with Ruffini endings possessed a kidney‐shaped nucleus and enveloped the axoplasmic spines with their cytoplasmic processes. From these morphological features, the cells in question were identified as the K‐cells described by Everts et al. (1977). These K‐cells developed Golgi apparatus and rough endoplasmic reticulum, suggesting active synthesis of proteins. Immunohistochemistry at the electron microscopic level revealed an intense immunoreactivity for S‐100 protein in the cytoplasm of the K‐cell and led to a conclusion that the K‐cells were terminal Schwann cells associated with Ruffini endings, presumably corresponding to the lamellar cells in the inner bulb

ISSN:0003-276X    

DOI:10.1002/ar.1092230114

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

年代:1989

数据来源: WILEY

摘要:

AbstractA simple, inexpensive method is described for embedding Prolene with tissue samples to provide landmarks for fiducial points to align serial sections in tissue reconstructions. Prolene is a monofilament suture material that can be easily sectioned with diamond knives to provide circular markers in each section. The sections are photographed, the negatives are projected through an enlarger and the contours, Prolene circles, and scratches from the diamond knife are traced onto paper. These landmarks establish a framework for assigning fiducial points that are necessary for the correct alignment of the contours. No special equipment is needed for embedding the Prolene and the method is adaptable for both automated and nonautomated computer systems. An example of this method for tissue alignment is given using embryonic limb tissue to determine the spatial organization of developing blood vessels as demonstrated by computer reconstruction.

ISSN:0003-276X    

DOI:10.1002/ar.1092230115

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

年代:1989

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092230116

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

年代:1989

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092230101

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

年代:1989

数据来源: WILEY