Adenine uptake by rat connective tissue cells with special reference to macrophage precursors.
After 3 daily injections of [14C]adenine ([14C]A) (1 microCi/g body weight each) into young adult rats, the large majority of typical, spindle-shaped fibroblasts in the connective tissues of most organs showed almost no labeling, with the exception of a few weakly labeled ones. In contrast, in the interstitial connective tissues of pancreas and heart, unexpectedly numerous mesenchymal cells were found to exhibit especially strong labeling with [14C]A even after RNase treatment. Such cells had a large, round or ovoid, euchromatic nucleus and showed the blast-like appearance. The term mesenchymal cells was used to denote a special type of connective tissue cells that retain the potentiality of embryonic mesenchymal cells. Double labeling experiments using [14C]A and trypan blue by 7 daily injections (1 microCi/g body weight of [14C]A and 3 ml/rat of 0.5% aqueous solution of trypan blue each) disclosed that the mesenchymal cells exhibiting heavy [14C]A labeling did not ingest trypan blue at all. It was further revealed that, in addition to the mesenchymal cells, macrophages showing a remarkable trypan blue uptake were also labeled with [14C]A, though to a lesser extent than were the former cells. Moreover, transitional forms between the mesenchymal cells and macrophages were occasionally observed. The transitional forms were characterized by having the capacities not only for a fairly high rate of DNA synthesis but also of ingesting trypan blue, though to a slight extent. On the basis of the above findings, it can be stated that the mesenchymal cells showing heavy labeling with [14C]A are most likely the precursor cells of macrophages.
Osogoe
B
B
Umebayashi-Yanagi
M
M
D000225:Adenine / Q000493:pharmacokinetics*; D000818:Animals; D001345:Autoradiography; D002250:Carbon Radioisotopes; D002454:Cell Differentiation; D003239:Connective Tissue Cells; D008264:Macrophages / Q000166:cytology*; D008297:Male; D008648:Mesoderm / Q000166:cytology; D051381:Rats; D011919:Rats, Inbred Strains; D014343:Trypan Blue
D002250:Carbon Radioisotopes; D014343:Trypan Blue; D000225:Adenine