Prothymocytes in mouse fetal liver.
Prothymocytes in fetal liver were characterized in an in vivo thymus regeneration assay. The frequency of prothymocytes in fetal liver is about 10.7% of that determined in normal bone marrow cells whereas the frequency of colony forming unit-spleen (CFU-S) in fetal liver is 24.4% of that in normal bone marrow cells. The lower level of prothymocytes leads to a delay in the development of thymus derived cells after transplantation of fetal liver cells when compared to bone marrow transplantation. There were no significant changes in the frequencies of both CFU-S and prothymocytes between 12 and 16 days from gestation. Fetal liver prothymocytes and CFU-S have a low (1.065 g X cm-3) but similar buoyant density when compared to their density in bone marrow cells (1.070 g X cm-3). These results reflect the close relationship between prothymocytes and CFU-S and might explain the differences in the development of the cellular immune system after transplantation of bone marrow and fetal liver cells.
D000818:Animals; D002469:Cell Separation; D002499:Centrifugation, Density Gradient; D003114:Colony-Forming Units Assay; D005865:Gestational Age; D008099:Liver / Q000196:embryology*; D051379:Mice; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology*