Electronic Resource
New York, NY [u.a.]
:
Wiley-Blackwell
The @Anatomical Record
179 (1974), S. 463-475
ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The human fetal thymus was studied at stages from 9 to 20 weeks of gestation. At 9 weeks of gestation the human fetal thymus contained lymphoid cells and was vascular although it was not yet lobulated nor did it have a cortex and medulla. By 12 weeks the thymus was lobulated and at 14 weeks a cortex and medulla could be distinguished, although the medulla was often more densely cellular than the cortex. By 18 weeks there were many lobules and a mature looking cortex and medulla. Large lymphocytes at all stages of thymus development studied were irregular in shape and often had blunt pseudopodia-like cytoplasmic extensions, or more slender cytoplasmic extensions. They also often possessed numerous elongated mitochondria, a large Golgi complex and strongly basophilic cytoplasm. Large lymphocytes were not attached to the epithelial cells by desmosomes although some of the cytoplasmic extensions from them were in association with extensions from epithelial cells. Primitive medium-sized lymphocytes at all stages studied were round in shape and had fewer mitochondria than the large lymphocytes. Epithelial cells were much less basophilic than the lymphoid cells and usually contained aggregates of glycogen. Occasional macrophages were observed within the developing thymus after 12 weeks of gestation and one granulocyte was observed within the thymus at 9 weeks while numerous granulocytes were seen within an interlobular septa at 14 weeks of gestation. Vessels were present within the thymus at all stages studied and at 9 weeks some had a boundary between the blood and thymus which consisted of only a thin endothelial cell and its basal lamina rather than the usual boundary of an endothelial cell and its basal lamina plus an epithelial cell and its basal lamina.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1091790406
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