Ultrastructural demonstration of transretinal migration by vitreal macrophages marked with latex particles.

The injection of 1.1-micrometer latex particles into the rabbit vitreous elicits an intravitral invasion of macrophages. The particle-filled macrophages are initially restricted to the vitreous, are later found at the vitreoretinal interface, and by 6 weeks are distributed throughout the inner layers of the retina. The phagocytes appear to lyse in the outer retinal layers, and the released particles are found between and within the cells of the photoreceptor region. The observations indicate that latex-marked macrophages from the vitreous can penetrate and migrate within the retina.