Histological Analysis of Vascular Patterns and Connections in the Ganglionic Eminence of Premature Neonates

Abstract

Capillaries of the ganglionic eminence (GE) are reported to display structural features, such as an unusually large diameter and thin walls that support the widely held notion that these vessels are immature, and an important factor in the pathogenesis of germinal matrix hemorrhage. In this study, structural characteristics of vessels in the GE of preterm neonates were studied with either collagen IV immunohistochemistry, which labels all vessels, or alkaline phosphatase enzyme histochemistry, a marker of arterioles and capillaries but not venules. Brains from 17 preterm neonates ranging in age from 24 to 38.5 weeks postconception were used to test the hypothesis that GE arterioles connect to a peculiar capillary bed that includes large sinusoidal vessels. Clearly identifiable arterioles were traced to their terminal branch points. We found that arterioles connected directly to alkaline phosphatase-positive capillaries with a diameter of approximately 5 µm, and not to large-diameter thin-walled sinusoids. The average diameter of GE capillaries measured only 0.30 µm, greater than that of capillaries in the cortex of the same specimen. Although it is commonly held that GE capillaries are structurally immature, our results indicate that arterial blood reaching the GE is delivered to a typical capillary bed.