Incorporation of Thymidine-H3 by Cells in Normal and Injured Mouse Spinal Cord

The mast cells of the mammalian central nervous system

“…Hence, so-called metabolic DNA has been described [Altman, 1963;Haas et al, 1970], and Reinis [1972] has shown that the number of neuronal nuclei that take up 3H-TdR is increased in the thalamus and frontal cortex of adult rats after training (passive avoidance learning)! However, normally as we also found, most of the uptake is by neuroglial elementsmostly oligodendrocytes, some microglia and very few astrocytes -vascular endothe lial cells, leptomeningeal cells, adventitial fibrocytes and subependymal cells [Koenig, 1960;Smart, 1960;Smart and Leblond, 1961;Adrian and Walker, 1962;Altman, 1963;Hommes and Leblond, 1967;Swarz and Del Cerro, 1977]. The growth cycle for glial and endothelial cells is on the average about 20 h and about 17% of the daughter cells of neuroglial division become pyknotic and are eliminated [Korr et al, 1975].…”

“…Thus generally, the demonstration of mitotic figures in normal adult mammalian CNS was more difficult than was the uptake of 3H-TdR although, for some unknown reason, this was easier in the guinea pig [Smart and Leblond, 1961;Adrian and Walker, 1962;Hommes and Leblond, 1967], The uptake is, of course, usually con sidered as heralding division, however, uptake by nuclei of mature neurons, which are known not to undergo division, throws doubt on this. Hence, so-called metabolic DNA has been described [Altman, 1963;Haas et al, 1970], and Reinis [1972] has shown that the number of neuronal nuclei that take up 3H-TdR is increased in the thalamus and frontal cortex of adult rats after training (passive avoidance learning)!…”

Effects of Interleukin-1 and Tumor Necrosis Factor-α on Astrocytes, Microglia, Oligodendrocytes, and Glial Precursors in vitro

“…Both astrocytes and microglia undergo mitosis in vivo in response to injury by trauma or disease [1][2][3][4][5]. Gliosis refers to the process of proliferation and hypertrophy of astrocytes and includes an induction or amplification in the number of the cytoplasmic processes.…”

“…There is some question as to whether gliosis interferes with axonal and myelin repair after damage or destruction has occurred [2,5,6]. Changes in microglia involve an increase in cell number and activation of ameboid microglia or reactivation of resting or ramified microglia to proliferate and become phagocytic [1,11], Microglia can be stimulated to prolif erate by astrocyte-derived factors [12][13][14]. Activated mi croglia and their cytokine products are implicated in perpetuation of central nervous system (CNS) disease [13,15,16].…”

Electron Microscopic Study of Macrophages Appearing in a Stab Wound of the Brain of Rats Following Intravenous Injection of Carbon Particles

“…In the past few years, it has been demonstrated repeatedly that some of the macrophages appearing in damaged and degenerating neural tissue originate from circulating monocytes (ADRIAN and WALKER, 1962;KONIGSMARK and SIDMAN, 1963;OLSSON and SJOSTRAND, 1964;HUNTINGTON and TERRY, 1966;ADRIAN and SMOTHERMON, 1970;KITAMURA, HATTORI and FUJITA, 1972;ADRIAN and WILLIAMS, 1973). The results of the above-mentioned workers are primarily based on radioautographic studies in which 3H-thymidine was used to label circulating monocytes in different animals before damaging the nervous tissues in various ways, e.g.…”