Studies on developing retinal vessels. X. Formation of the basement membrane and differentiation of intramural pericytes.

Abstract

PREVIOUS studies (Ashton, Ward, andSerpell, 1953, 1954), have demonstrated that the kitten is an ideal animal for studying developing retinal vessels. Since these vessels reach the periphery of the retina about three weeks after birth, all stages of their development can be studied in the same eye.The present study deals with the origin of the intramural pericytes and the formation of the basement membrane of the retinal vessels. Material and MethodsNormal retinae from kittens 1 to 8 days old were used in this investigation.For light microscopical study the specimens were digested with pepsin-trypsin technique (Ashton, 1963) and stained with periodic acid-Schiff and haematoxylin (PASH).For electron microscopical study the animals were anaesthetized by intraperitoneal injections of Nembutal, and their eyes were enucleated and rapidly opened by a coronal section through the ora serrata. The vitreous was gently removed; the posterior half of the eye was then cut into four pieces and immersed in chilled 1 per cent. isotonic veronal buffered osmium tetroxide. In order to allow better penetration of the fixative the retina was separated from the choroid with a thin spatula. The fixation was carried out for two hours at 4°C. temperature. The retinae were dehydrated in graded concentrations of alcohol and embedded in Epon and Araldite. Sections 1 t thick were cut from the whole block, using a Huxley microtome, stained with 1 per cent. alkaline toluidine blue, and studied by light microscopy. Thin sections were cut from selected areas of the block, stained with uranyl acetate in acetic acid, followed by 1 per cent. lead citrate, and viewed by an A.E.I. EM6 electron microscope. ObservationsLight Microscopy.-Normal developing retinal vessels in the kitten show a vascular network comprising a pattern of polygonal spaces, usually pentagonal, which are larger on the arterial side of the capillary circulation and gradually *

Characterization of Smooth Muscle Cell and Pericyte Differentiation in the Rat Retina In Vivo

“…Furthermore, in contrast to the adult retinal vasculature, the developing retinal vasculature is highly unstable, with active angiogenesis occurring in close proximity to vascular segments undergoing vessel retraction 32 and with vessels regressing in response to hyperoxia-induced VEGF withdrawal. 7 Studies have shown that mural cells are present on early retinal capillaries 25,[33][34][35][36] and that SMA expression becomes more widespread with maturation. 8,36 With the use of wholemount preparations, we undertook a detailed marker analysis of mural cell differentiation in a growing vasculature.…”

Animal models of oxygen-induced retinopathy

“…Previous studies had suggested that this is likely due to the lack of mesenchymal cells in the kitten retina in contrast to the situation in the human (20,50,51). Subsequent work by Halasz et al and others showed the presence of these cells in kitten retina (12,52,53). Another possibility is that, since mesenchymal cells are present in isolated foci, they are unable to produce sufficient traction for detachment.…”

Cellular-Level Analysis of Retinal Blood Vessel Walls Based on Phase Gradient Images

“…The retinal endothelium is responsible for the exchange of oxygen, nutrients, and waste. The retina is the tissue with the greatest metabolic demand in the body and since the retinal capillaries lack precapillary sphincters, they remain perfused continuously [1,2]; therefore, retinal oxygen concentration remains high independent of systemic hemodynamics and atmospheric partial pressures [3]. However, even in early diabetes mellitus (DM), there is loss of pericytes and perturbations in retinal vascular physiology.…”