Morphological studies of the hyalocytes in the chicken eye: scanning electron microscopy and inflammatory response after the intravitreous injection of carbon particles.

Hyalocytes in the pecten oculi and ciliary body of adult chickens and their response to Escherichia coli were investigated by transmission and scanning electron microscopy and the inflammatory response following the intravitreous injection of colloidal carbon examined by microscopy. In normal chickens, the hyalocytes were mainly found on the pleats of the pecten oculi and on the ciliary body. There were no hyalocytes on the retina. There is thus a close relationship between the vasculature in the tissues surrounding the vitreous chamber and the distribution of hyalocytes. The hyalocytes, which were predominantly spindle shaped or oval in contour, displayed a ruffled surface with occasional blebs, filopodia and lamellipodia. Flattened hyalocytes with relatively few and short pseudopodia were frequently observed, especially on the ciliary body. Hyalocytes responded quickly to E. coli bacteria which they phagocytosed. The response to colloidal carbon in the vitreous chamber had 3 distinct changes. In the 1st (2 d after carbon injection), the hyalocytes, the resident macrophages, actively ingested the carbon particles without significant leucocyte recruitment. In the 2nd stage (at 7-14 d), a large number of macrophages infiltrated the ciliary body and emigrated into the vitreous chamber. In the 3rd stage (at 30 d), the infiltration by macrophages into the ciliary body was complete. The carbon-laden macrophages disappeared from the vitreous body but accumulated on the pecten oculi and retina. They were exclusively drained through the scleral venous sinus in the iridocorneal angle.