The fetal thymus at 13 days of gestation withstands transplantation and develops normally under the renal capsule of a syngenic host. Distinct differences were observed between the fetal thymus grafts and grafts from neonatal or adult thymus donors. The fetal thymus graft did not undergo the rapid and severe necrosis observed when adult thymus was grafted. Furthermore, when thymuses were transp...

Thymus and spleen grafts from neonatal C57BL mice were implanted beneath the kidney capsule of (A x C57BL) F(1) hybrids. At various intervals after implantation, the grafts were analyzed serologically. Cells of each graft were tested for the presence of cells of host origin, TL (thymus-leukemia) antigenicity, and sensitivity to the cytotoxic effect of guinea pig serum (GPS). Thymus grafts showe...

1. Though thymus-fed salamander larvae often metamorphose normally, thymus feeding sometimes retards and in rare cases inhibits metamorphosis completely. 2. The addition of normal food to a thymus diet abolishes the inhibitory effect of the thymus. 3. Addition of a small quantity of iodothyrin leads rapidly to precocious metamorphosis of thymus-fed larvae. 4. The inhibitory effect of the thymus...

Thymus function is thought to depend on a steady supply of T cell progenitors from the bone marrow. The notion that the thymus lacks progenitors with self-renewal capacity is based on thymus transplantation experiments in which host-derived thymocytes replaced thymus-resident cells within 4 wk. Thymus grafting into T cell-deficient mice resulted in a wave of T cell export from the thymus, follo...

Lymphopoiesis was studied in 3-month-old normal C57Bl mice and in 3-month-old C57Bl mice carrying from 12 to 48 C57Bl thymus grafts using tritiated thymidine labeling. Thymus graft lymphopoiesis was found to be identical with that of normal thymus tissue and the presence of thymus grafts was found to have no influence on host thymus lymphopoiesis. No evidence was found that the massive amounts ...