Early morphogenesis of the canine lens, hyaloid system, and vitreous body.

This study deals with the early morphogenesis, from day 25 to day 35 post coitum (D25-D35), of the canine lens, lens capsule intraocular vascular system, and vitreous body. The breeding method used provides a higher accuracy as to the gestational age of the obtained fetuses than employed previously. The development of the lens, the intraocular vascular system, and the vitreous body of the dog's eye is analogous to that in other mammal species. The findings of this study, combined with data obtained from the literature, suggest that the period during which ocular development takes place is earlier in larger mammalian species than in the smaller ones. Previous descriptions of ocular development in other mammalian species, and one in the dog, reported that the development of the lens capsule starts posteriorly and proceeds towards the anterior part of the lens vesicle. In the present study, the periodic acid--Schiff positive anlage of the capsule was observed to fully surround the lens vesicle at D25, a development that is different and earlier than described previously in the dog and different from that described in other mammals. Moreover, a clear thickening of the capsule was not observed until capillaries of the tunica vasculosa lentis had reached its proximity.