ISSN:
1432-0568
Keywords:
Adrenal cortex
;
Human embryo
;
Cytodifferentiation
;
Mitochondria
;
Smooth endoplasmic reticulum
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Adrenal glands of early human embryos from 20 to 150 mm (CRL) were examined with the aid of the electron microscope. 1. The outer-zone cells of these embryos were somewhat smaller than the inner-zone cells and contained club-shaped or oval mitochondria with laminar or tubular cristae in the cytoplasm. The mitochondria in the inner-zone cells were also round, oval or club-shaped; their cristae are generally tubular or laminar in 20-, 21- and 22 mm embryos, and tubular or vesicular in 68-, 78-, 95-, 115-, and 150-mm embryos. With advancing cytodifferentiation, mitochondria tended to become larger and round in shape. The mitochondrial cristae in the cortical cell were considered to be transformed from the laminar type to the tubular one and then to the vesicular one with advancing functional differentiation. 2. The elements of endoplasmic reticulum were very poor, and numerous free polysomes were distributed throughout the cytoplasm in the outer-zone cells of these embryos. Especially in 68-, 78-, 95-, 115-, and 150-mm embryos, small areas of the cytoplasm contained parallel, regularly arranged lamellar rough endoplasmic reticulum. The end of the rough element was continuous with the tubule of smooth endoplasmic reticulum. The elements of smooth endoplasmic reticulum are thought to be derived from those of rough endoplasmic reticulum. A few inner-zone cells of embryos 20–22 mm in length and most inner-zone cells of embryos 68–150 mm in length contained small areas of lamellar profiles of rough endoplasmic reticulum in a parallel arrangement in the cytoplasm. The end of each element was related to that of smooth tubular endoplasmic reticulum. The tubular smooth endoplasmic reticulum occupied most of the cytoplasm in some inner-zone cells of embryos 20–22 mm in length and in most cells of embryos 68–150 mm in length. 3. Lipid droplets were very few in both inner- and outer-zone cells of these embryos. 4. Glycogen particles were abundant in both outer- and inner-zone cells of the early embryo, and reduced in quantity with advancing cytodifferentiation. In embryos 95\2-150 mm in length glycogen particles were difficult to find in the cortical cell. 5. Small dense bodies and coated vesicles were often seen in or near the Golgi region of the inner-zone cell at all embryonic stages.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00519133
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