The proximal tibial epiphyses of 18–21-day-old fetal rats have been studied by thymidine-3H radioautography. The results reveal that the label is incorporated into two types of osteogenic cells: (a) a spindle cell type (A cells) with characteristics generally associated with matrix production, including an extensive development of the endoplasmic reticulum and the presence of large intracellular accumulations of a dense, finely granular material, morphologically identifiable as glycogen; and (b) a rounded cell type (B cells) with morphological features similar in degree and kind to those of the developing neutrophilic leukocyte, including an abundance of free ribosomes and mitochondria and a complex Golgi apparatus associated with dense specific granules, morphologically identifiable with primary lysosomes. These results, along with the occurrence of recognizable, labeled, immature, perivascular forms of both of these A and B type cells, lead to the conclusion that the specialization of osteogenic cells into osteoclasts and osteocytes may involve separate pathways of cytodifferentiation.
Article| October 01 1967
THYMIDINE-3H ELECTRON MICROSCOPE RADIOAUTOGRAPHY OF OSTEOGENIC CELLS IN THE FETAL RAT
Bronnetta L. Scott
From the Medical Research Programs, Long Beach Veterans Hospital, Long Beach, California, and the University of Alabama Medical Center, Birmingham, Alabama 35233.
The author's present address is the University of Alabama Medical Center
Received: March 10 1967
Online Issn: 1540-8140
Print Issn: 0021-9525
Copyright © 1967 by The Rockefeller University Press
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Bronnetta L. Scott; THYMIDINE-3H ELECTRON MICROSCOPE RADIOAUTOGRAPHY OF OSTEOGENIC CELLS IN THE FETAL RAT . J Cell Biol 1 October 1967; 35 (1): 115–126. doi: https://doi.org/10.1083/jcb.35.1.115
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