Abstract

Ganglionic eminence initially appears as a slight swelling in the floor of the cerebral vesicle during the 5th fetal week and attains maximum prominence late in the 4th fetal month; it then declines in relative size, and nearly disappears after birth. The ganglionic eminence constitutes a collection of the proliferating cells throughout most of span of gestation and supply neuroblasts and spongioblasts to basal ganglia and pulvinar region of thalamus and cerebral cortex. Nowadays intraventricular hemorrhage predominantly occurs in preterm infants of less than 32 weeks gestational age, and the intraventricular hemorrhage arises most frequently from rupture of a ganglionic eminence hemorrhage is equally frequent in both hemispheres and is associated with an extensive destruction of the capillary bed without arterial or venous rupture. Although fibrin thrombi are seen within veins in relation to ruptures at the capillary vein junction, the other study reveals little or no fibrin is to be seen within the ganglionic eminence hemorrhage presumably due to the high fibrinolytic activity within this region of the immature brain. Accordingly this study was planned to evaluate the ganglionic eminence of fetal brain in two aspects, i.e., morphological development of ganglionic eminence during gestation and functional maturation by measuring fibrinolytic activity of various portions of developing brains. To evaluate the development of ganglionic eminence a total of 97 brains of Korean fetuses of gestational ages ranging from 16 to 37 weeks, was studied; 62 for morphological study and 35 for functional study. The fetuses were products of therapeutic abortions, and were proved to be normal after complete examination of fetuses and placentas. The brains were removed as soon as possible after delivery, and were fixed in 10% formalin for 1 to 2 weeks before being examined. Representative blocks containing white matte around lateral ventricle, ganglionic eminence, caudate nucleus and thalamus on the serial coronal sections. Through routine histological procedure, slides were made and stained with hematoxylin and eosin for microscopical examination of the ganglionic eminence and striatum. The fibrionlytic activity of the tissue was measured by fibrin plate method of Astrup and Albrechtsen and the amount of lysis expressed as area/mg of wet tissues. As controls comparable aliquots of 2M potassium thiocyanate or saline alone had no fibrinolytic activity. To detect the in vivo fibrinolysis, fibrin and/or fibrinogen degradation product, staphylococcal clumping tests for the tissue extracts were performed. Following results were obtained. 1) The ganglionic eminence was well formed and located at the lateral side of terminal vein and over the caudate nucleus and protruded into the lateral ventricle. 2) The thickness of the ganglionic eminence is reached to maximum width by 20th week of gestation and is shown a progressive reduction till 30th week, and revealed sharp reduction after 31th week of gestation and became no longer recognizable after 37th week of gestation. 3) The ependymal layer was most thickened at 16~19th week of gestation, showing 6~8 layers with numerous mitoses and declined to 2~3 layers at 28~31th week of gestation and no more mitosis was found. 4) The distribution of capillary beds were most pronounced at 16~19th week of gestation and the permeation of the capillaries to the ependymal zone and decreased in number after 20th week of gestation. The medium sized, well developed veins were demonstrable at the junction of ganglionic eminence and caudate nucleus from 24th week of gestation. 5) The fibrinolytic activity of the choroid plexus and leptomeninges were significantly increased than the other areas(p<0.005) and there was no evidence of gestational changes. 6) The fibrinolytic activity of the ganglionic eminence was no more pronounced than those of cerebral cortex, periventricular white matter, cerebellum and spinal cord.