Protein incorporation by isolated amphibian oocytes. I. Preliminary studies

Abstract
Developing Xenopus oocytes removed from the ovary and divested of their outermost cellular layers (theca and surface epithelium) will incorporate protein continuously over a period of at least two to six days when cultured in vitro. The rate of protein incorporation depends upon:(a) the extent to which the donor has been stimulated by gonadotropin; (b) the size of the oocyte; and (c) the protein composition of the medium, since a mechanism exists to sequester selected protein. Protein uptake is negligible when oocytes are cultured either with all their cellular layers intact or with all their cellular layers removed. These results imply that the outer surface epithelium is relatively impermeable to protein and that the integrity of the investing follicular epithelium is essential for vigorous protein incorporation by the oocyte.