Microcirculation of human fetal posterior root ganglia: a scanning electron microscopic study of corrosion casts.

The vasculature of lumbar posterior root ganglia was investigated in human fetuses aged 17-24 weeks; using the corrosion casting technique and scanning electron microscopy. The arterial supply consisted of one main artery and occasional arterioles entering the ganglion at its pole and running axially, while the venous drainage was located at the periphery of the ganglion, thus indicating a centrifugal pattern of blood flow. The dense capillary network of the ganglion showed the roughly parallel course of the vessels in the central zone and an irregular arrangement in the peripheral zone where capillaries formed "nests", probably surrounding individual perikaryons of ganglionic cells. The capillaries had a sinusoidal character with numerous dilatations about twice the normal capillary size, as well as occasional larger vascular spaces resulting from capillary interconnections and suggesting the intussusceptive type of angiogenesis.