IMMUNOHISTOCHEMICAL CHARACTERIZATION OF DEVELOPING AND MATURE PRIMATERETINAL BLOOD-VESSELS

Purpose. To characterize developing retinal blood vessels with vascula r markers and to relate the histochemical profile of maturing vessels to morphologic stages in retinal vascular development. Methods. Vessel s were examined in frozen and paraffin-embedded retinas and in wholemo unts of Macaca monkeys ranging in age from fetal day 75 (F75) to adult hood, Endothelial cells were visualized immunohistochemically using an tisera to von Willebrand's factor and CD31 with lectins Ulex europaeus , Bandeiraea simplicifolia, peanut agglutinin, Ricinis communis, and w heat germ agglutinin, and by ATPase and ADPase enzymatic histochemistr y. Antibodies to vascular basement membrane and matrix markers laminin , fibronectin, and collagen types I and VIII, and antisera recognizing cell cycle-specific nuclear proteins (cyclin, Ki-67, Mib-1) also were used. Results. Newly formed and mature vessels were reactive with rea gents specific for CD31, von Willebrand's factor, types I and VIII col lagens, laminin, fibronectin, U. europaeus, R. communis, and peanut ag glutinin. Wheat germ agglutinin labeled vessels only after pretreatmen t with neuraminidase. All vascular markers appeared simultaneously, bu t some were distributed differentially between capillaries and larger vessels, along the central-peripheral extent of a vascular plexus, and among different vascular laminae. Markers of vessels failed to label spindle-shaped presumed vascular precursor cells lying peripheral to t he advancing vessels during development. Spindle cells exhibited cycli n, Ki-67, and Mib-1 immunoreactivity. Conclusions. Immature and mature vitread and sclerad vessels displayed histochemical profiles that wer e qualitatively similar but that had subtle quantitative differences. Results do not support identification of spindle-shaped cells as vascu lar precursors in the developing monkey retina and are discussed in re lation to mechanisms of retinal vascularization.