DNA replication in lens vesicles of Ambystoma maculatum embryos implanted into ocular or extra-ocular sites of host larvae

Abstract

In Ambystoma maculatum , lens vesicles from donor embryos were transplanted into the dorsal fins or into the lentectomized eyes of larval hosts. From one to 30 days after operation, the hosts were injected with [ 3 H]thymidine and fixed 3 hr later. Autoradiographs were prepared with Kodak NTB-3 liquid emulsion. The lens vesicles developed normally in the larval eyes and differentiated into lenses with primary and secondary lens fibers which grew almost as large as the lenses in the eyes of donor controls. Many cells in the lens epithelium incorporated [ 3 H]thymidine following the three hour exposure to the isotope (mean thymidine index=37·2%). In the fin, lens fibers also differentiated from most of the lens vesicles but the latter remained small and the number of labeled cells in the lens epithelium was greatly reduced (mean thymidine index=7·1%). It was concluded that the larval eye environment, especially the neural retina, supports DNA synthesis and mitotic activity in the cells of the embryonic lens vesicle and the lens epithelium of the young lens.