Mast-cell precursors in the skin of mouse embryos and their deficiency in embryos of Sl/Sld genotype.
Concentration of mast-cell precursors in the skin and liver of mouse embryos was evaluated by the limiting dilution analysis. The concentration of mast-cell precursors in the liver of (WB X C57BL/6)F1 (hereafter WBB6F1)-+/+ embryos reached the maximum level at Day 15 of the pregnancy, whereas the concentration in the skin at Day 17. The concentration of 17-day skin was about 10 times as high as that of 15-day liver. Appearance of morphologically identifiable mast cells in the skin followed the increase in concentration of the skin precursors. Concentrations of mast-cell precursors in the skin and liver of mutant embryos of Sl/Sld genotype were also measured to clarify the mechanism of mast-cell depletion in this mutant. Although the concentration of mast-cell precursors in the liver of WBB6F1-Sl/Sld embryos was comparable to that of the WBB6F1-+/+ embryos, the concentration in the skin of the Sl/Sld embryos was about 1% that of the +/+ embryos. Moreover, the concentration of morphologically identifiable mast cells in the skin of the Sl/Sld embryos was about 0.1% that of the +/+ embryos. Thus, mast-cell production in Sl/Sld embryos seemed to be suppressed at two stages; (1) during deficient invasion of liver-derived precursors into the skin, or the decreased proliferation of these cells, or both of these causes, (2) during differentiation of the precursors into mast cells.
D000818:Animals; D008099:Liver / Q000166:cytology / Q000196:embryology; D008407:Mast Cells / Q000166:cytology*; D051379:Mice / Q000196:embryology / Q000235:genetics*; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D012867:Skin / Q000166:cytology / Q000196:embryology*