| Abstract: | Blood vessels of the human telencephalic germinal matrix during the tenth through the twenty-second week of gestation have been examined by light and electron microscopy. In all fetuses studied the ependymal and sub-ependymal zones of the germinal matrix have a prominent vascular network. During the tenth and twelfth weeks of gestation, the endothelial cells are plump and display numerous organelles, junctional complexes, conspicuous luminal microvilli and stub-like abluminal projections. Coated and micropinocytotic vesicles were found both in the cytoplasm and on luminal and abluminal surfaces. In endothelial cells intracytoplasmic, membrane-limited, rod-shaped bodies were frequently observed. These bodies have been linked to endothelial thromboplastic and clotting activities and related to abnormal clotting status. Their role in the pathogenesis of subependymal germinal matrix hemorrhage in premature infants remains unknown. Pericytes apposing the endothelial cells were recognized in all gestational periods. The endothelial basal lamina and astrocytic end-feet are ill defined, and the extracellular space is pronounced. By the fifteenth and seventeenth weeks of gestation the endothelial cells are still large and now possess more numerous luminal microvilli and abluminal projections. At this stage the pericytes, basal lamina and astrocytic end-feet are all well developed, resulting in a decrease in the surrounding extracellular space. By the twenty-second week the endothelial cells possess few luminal and abluminal projections and the associated basal lamina, glia, pericytes and extracellular compartment appear mature. The relationship of the germinal matrix vasculature to the pathogenesis of subependymal hemorrhage is discussed. |
