[Immunohistochemical study on brain macrophages by monoclonal antibody--localization in fetuses and neonates]

Abstract

It has been controversial whether macrophages from blood circulation which have phagocytic activity exist in the normal central nervous system (CNS). Based on the data obtained from adult animals, the origin of phagocytes in the brain has variously been attributed to blood monocytes, pericytes and glial elements. On the other hand, in fetuses and neonates, although it is known that macrophages exist in the CNS, their precise period of appearance and distribution have not been investigated. In this paper, overall study on localization of the fetal and neonatal brain macrophages of mice was carried out immunohistochemically using monoclonal antibody against macrophage specific marker (Mac-1) and labeled avidin-biotin technique. The antibody used in the experiment well recognized blood monocytes and resident macrophages in various visceral organs both of the fetuses and adults. Mice ranging in age from embryonic day 10 (E 10) to postnatal day 21 (P 21) were examined chronologically. The cerebrums of E 10-E 12, E 14-E 19, P 0-P 21 were at the stage of matrix cell, neuroblast, and glioblast formation, respectively. In the CNS, macrophages first recognized, were located in the choroid plexuses of the fourth and lateral ventricles at E 14. Their number in the choroid plexus of the fourth ventricle increased at E 17-P 3 and gradually decreased thereafter. Macrophages in the cerebral parenchyme also appeared at E 14 in the matrix cell layer and they were detected in the migrating zone at E 15, E 17 and in the cortical plate at E 19.(ABSTRACT TRUNCATED AT 250 WORDS)