Growth stimulation of embryonic spleen graft by adult chicken spleen across a membrane filter barrier.

Abstract

1. In an attempt to further analyze the sequence of steps resulting in homologous splenomegaly in the chick embryo, the following series of experiments were conducted to elucidate, in particular, the role of the host spleen component in the absence of intact adult donor spleen cells. In the first series of experiments two 10-day chick embryos were joined together with paraffin but separated by cotton gauze, Dacron mesh or a piece of membrane filter which was punctured with many small holes. Spleen enlargement in both host embryos was observed when a piece of adult chicken spleen was implanted on the chorioallantoic membrane of one of the pair. When the two embryos were separated by an intact piece of membrane filter (Millipore THWP 0.45 µ, 25 µ thick) no enlargement was observed in the spleen of the embryo without the adult spleen graft. Because of the possibility that the contact between the chorioallantoic membrane and the membrane filter was not adequate, in order to encourage vascularization, a piece of 17-day embryonic spleen tissue was grafted on the chorioallantoic membrane of one embryo. This was joined with another embryo containing an adult chicken spleen graft. The two grafts as well as the two embryos were separated by a piece of membrane filter. Although enlargement of the spleen of the host with the embryonic spleen graft was not obtained, a striking enlargement of the embryonic spleen graft was elicited. Similar results were obtained when the membrane filter was washed with more than 100 cc. hot distilled water, but the number of poor or unsuccessful grafts was sharply reduced.2. These experiments reveal a differential response of spleen tissue from 17-day embryos and 10-day embryos to substances which are able to diffuse through the membrane filter from the adult spleen graft.