Scanning electron microscopy of the subarachnoid space in the dog. IV. Subarachnoid macrophages

Abstract

Young dogs of both sexes were used in this study. Transmission and scanning electron microscopy were utilized for the examination of the spinal cord and choroid plexus with emphasis on the study of free cells. These procedures were modified so that, in certain cases, the same cells observed in scanning electron microscopy could be analyzed internally by transmission electron microscopy. One half of the animals were injected under anesthesia with horseradish peroxidase for observation of phagocytosis. This study confirms that the free cells observed in the subarachnoid space with the scanning and transmission electron microscopes are identical. The internal morphology of these cells corresponds to that of macrophages. This is further substantiated by the ability of these cells to localize horseradish peroxidase in discrete vacuoles within their cytoplasms. Both pial macrophages and epiplexus cells localize peroxidase in an identical manner in the same animal after one injection. In addition macrophages on the surface of the pia mater respond to extravasated red blood cells in a characteristic manner including phagocytosis. The plentiful population of macrophages on the surface of the pia mater supports the concept that these cells are of major importance in maintaining asepsis in the subarachnoid space.

Non-neuronal cells in the spinal cord of nude and heterozygous mice. II. Agranular leukocytes in the subarachnoid and perivascular space

“…compartment (Morse & Low, 1972;Cloyd & Low, 1974;Malloy & Low, 1976). Clinical data indicate that small lymphocytes are also normally present in the C.S.F.…”

“…instead of lymph (Frederickson & Hailer, 1971) and is continuous with a real perivascular space of Virchow-Robin down to the capillary level in some regions (Frederickson & Low, 1969;Jones, 1970;Harriman, 1976). Pleomorphic macrophages are especially numerous on the spinal leptomeningeal surfaces (Cloyd & Low, 1974) and are derived in part by diapedesis of blood leukocytes through thin-walled veins (Malloy & Low, 1976;Oehmichen, 1978). However, a normal C.S.F.…”

Scanning electron microscopy of transitory subependymal cysts in the developing midbrain of postnatal rats.

“…The monocytic nature of amoeboid microglia receives further support from the present scanning electron microscope observations. Thus their pleomorphic surface features, i.e., blebs and pseudopodia are identical to those of monocytes and their derivative tissue macrophages, including the subarachnoid macrophages (WARFEL and ELBERG, 1970;GLOYDS and LOW, 1974;PARAKKAL et al, 1974;ALLEN and LOW, 1975;POLLIACK and GORDON, 1975;MALLOY and LOW, 1976;DEIMAN N and FAHIMI, 1979;POLLIACK, 1981). Similar features have also been described in amoeboid microglial cells present in the cavum septum pellucidum (TSENG et al, 1983) and in macro- phages in the subependymal cysts in the developing rat rhombencephalon (SIEVERS et al, 1981).…”

Some New Findings about Hofbauer Cells in the Chorionic Villi of the Human Placenta

“…On the other hand, there is a relation between the recently available three-dimensional images of Hof bauer cells [Castellucci et al, 1980a-c] and in vivo and in vitro scanning electron microscope (SEM) studies of the macrophages in various tissues [Malloy and Low, 1976;Merchant and Low, 1977;Powell and Muse, 1977;Merchant et al, 1979;Hocking and Golde, 1979], because both Hofbauer cells and in vivo and in vitro examined macrophages do not contain phago somes. However, in an SEM investigation by Orsentein and Shelton (1977] on mouse stimulated peritoneal macrophages, the cytoplasmic projections on the cell surface which are arranged end-to-end and form an extracellular area were reported to have a material swelling function.…”