The mast cells of the mammalian central nervous system

Abstract

The brains of young adult male and female Sprague-Dawley rats were studied with the electron microscope to determine the full ultrastructural picture of two types of perivascular granular cell. One of these, referred to here as the type I cell and described by both light and electron microscopy by several authors, including ourselves, has been reported to be a mast cell (MC) almost identical to MCs outside the CNS. The other, referred to here as the type II cell and described by many authors under almost as many names, was dealt with fully by Ibrahim in several reports and regarded by him as a type of MC. It is felt that the results warrant the conclusions that the type I cells are indeed MCs, while the type II cells are closely allied to the type I cells and probably better adapted to the function they subserve in the CNS of mammals. The similarities between the two cell types probably outnumber the dissimilarities and even these have their counterparts in MCs outside the CNS. The problem of the possible confusion between the type II cells and macrophages, whether reportedly within vessel walls or in the form of modified or special ‘pericytic’ microglia, is discussed. It is concluded that there is no justification for regarding these cells as macrophages. Because of the similarity between the type II cells and MCs, and because of the high lipid content of the type II cells, it is suggested that these elements be called neurolipomastocytes or neurolipomastocytoid cells.

Mast cells with gonadotropin-releasing hormone-like immunoreactivity in the brain of doves.

“…Mast cells generally circulate in precursor form and enter tissues where they complete their differentiation; basophils, which share some characteristics with mast cells, are granulated leukocytes that circulate in fully differentiated form and rarely enter tissues (3). Mast cells enter the brain during the neonatal period (4) and are usually associated in the adult with the blood vessels; they lie just inside the blood-brain barrier (5)(6)(7)(8)(9)(10)(11)(12)(13). After insult to the brain or damage of brain tissue by disease (5), mast cells enter deeper into the neuropil of the central nervous system (CNS).…”