Open AccessELECTRON MICROSCOPIC OBSERVATION OF THE HUMAN THYMUS OF THE FETUS AND THE NEWBORN
Author(s) -
Hirokawa Katsuiku
Publication year - 1969
Publication title -
acta patholigica japonica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.73
H-Index - 74
ISSN - 0001-6632
DOI - 10.1111/j.1440-1827.1969.tb00689.x
Subject(s) - medulla , pathology , endoplasmic reticulum , electron microscope , parenchyma , fetus , cell type , reticulum , granule (geology) , biology , anatomy , chemistry , microbiology and biotechnology , cell , medicine , physics , pregnancy , paleontology , genetics , optics
The human fetal thymus has been systematically studied by electron microscopy. The basic structure of the thymic parenchyma is a spongy meshwork, loose in cortex and dense in medulla, composed of two types of epithelial reticulum cell. The meshworks are packed predominantly with thymocytes of variable stages of maturation and partly with macrophages. type, found only in the medulla, is hypertrophic and has characteristic The first type of epithelial reticulum cells is slender and electron opaque, forming supporting element of meshwork(the slender type). The second type, found only in the medulla, is hypertrophic and has characteristic vesicles of two sorts (the hypertrophic type), the large one of which is provided with microvillous projections and contains fine granular substance of moderate electron density which corresponds to the PAS positive granule of METCALF 1 . SO it might be suggested that the hypertrophic ones have an endocrine activity. The HassaU's corpuscle is composed of cellular aggregation of the hypertrophic type. The function of the thymus in the human fetus is discussed laying stress on the epithelial reticulum cell.