Dead Cells can Be Phagocytosed by Any Neighboring Cell in Early Developing Rat Brain

Abstract

We investigated phagocytosis in vitro, on tissue samples of rat brain from 10th to 18th embryonic days. Our results show that, in the early stage of development, degenerated cells can be phagocytosed by any neighboring cell in the brain. The phagocytosing cells were of the same type as the others and did not resemble microglia in the samples obtained from 10th to 14th embryonic days. In embryonic rat brain microglial cells have been reported to appear after the 12th day, while phagocytosing cells were already observed in our 10- and 12-day materials as well. The general ability of embryonic rat brain cells to phagocytose is further supported by the results of horseradish peroxidase studies. Typical microglial cells could be observed in our 16- and 18-day materials. On the basis of our results we do not intend to modify the notion on the origin of microglia. Our concept is that the microglia gradually replaces the multipotential cells of the embryonic brain in their “cleaning-off” function as the differentiation of these latter cells progresses.

Keywords:

• embryonic brain
• phagocytosis
• microglia
• horseradish peroxidase