Intraocular vasculature formation precedes extraocular vasculature penetration of mouse eyes.

The posterior ocular circulatory system comprises choroidal vasculature and central retinal and posterior ciliary arteries (PCAs) that are fundamental for ocular tissue maintenance. Much is known about the development of the retinal vascular system, but that of the posterior ocular circulation system remain obscure. Therefore, we aimed to clarify the development of the intraocular vasculature involved in the posterior ocular circulation system. Choriocapillaris and hyaloid capillaries are formed in situ and de novo through the endothelial differentiation of hemangioblasts. The intraocular segments of the hyaloid artery penetrate the retina before extraocular segments appear. The intraocular segments of PCAs arise from the hyaloid artery before the extraocular segments reach the eye. The posterior ocular circulation system apparently synchronizes with events throughout the entire process of ocular development. The intraocular vasculature notably formed before the extraocular segments reached the eyes. Our findings provide a novel perspective on ocular development and might facilitate understanding of eye diseases in humans.