Permeability of the pineal gland of the viscacha (Lagostomus maximus maximus) to the lanthanum hydroxide

Abstract

The introduction of lanthanum to study the transport across the capillary endothelium and also as tracer in the skeletal muscle was followed by the use of this salt as an intercellular marker. One of the potential routes for the secretory products of the pineal is the circulatory system. The other postulated route is the ventricular cerebrospinal fluid (CSF). In this sense, a junctional interrelationship between the pineal gland and the CSF has been postulated in different mammals. The present work contains observations on the junctions between the parenchymal cells and the morphological characteristics of the blood vessels of the viscacha pineal using a lanthanum as extracellular marker.A total of five adult male viscachas (4 to 5 kgs of body weight) are used. The animals are collected near San Luis, Argentina (33°20’ South latitude; 760 m altitude) during summer and winter seasons. On the day of sacrifice the rodents are anesthetized, the brain exposed and a solution of fixative-lanthanum is injected slowly into the third ventricle. The pineal gland is then removed and immersed for 2 h more in the same fixative without lanthanum hydroxide. Ultrathin sections are examined in TEM.