Intraocular growth and differentiation of tissue fragments isolated from primitive streak-stage mouse embryos.

Small tissue fragments were isolated from 5 different regions of mouse embryos at the primitive streak-stage and were grafted ectopically into the anterior eye chambers of syngeneic adult mice. Of the grafts, 22-66% became attached to the iris and were vascularised within 2-3 days. The attached grafts grew in size and formed loose aggregates of embryonic cells. During the fourth week in oculo, fully differentiated tissues representing derivatives of all three germ layers were found within the grafts. No differences in the composition of tissues derived were observed in grafts obtained from different regions of the embryo except that the endodermal grafts formed endodermal cysts only. The size of the original fragments did not affect their in oculo differentiation but smaller fragments had a lower chance of intraocular survival.