Ependymal absorption of luteinizing hormone-releasing hormone injected into the third ventricle of the rat.

LRH injected into the third ventricle induced increases of serum LH and FSH in the rat. Following injection of LRH-125I into the third ventricle, autoradiographic grains were concentrated in the ependymal cell bodies and ependymal processes in the median eminence. Aggregations of grains were also found in the capillaries of the portal vessels, and in both sinusoids and parenchymal cells of the adenohypophysis. These findings show that the ependymal cells represent a link between the cerebrospinal fluid and the portal blood.