Changes in the numbers of neurons and glial cells in the lateral geniculate nucleus of the monkey during retrograde cell degeneration

The time‐course of disintegration of neurons, and the concomitant reactions of various types of glial cells, in the dorsal nucleus of the lateral geniculate body (LG) were studied in 12 Rhesus monkeys sacrificed in groups of two at time intervals of 1, 3, 6, 12, 25 and 50 weeks following unilateral removal of the occipital lobe. The change in the mean number of neurons, astrocytes, oligodendrocytes and microglia, found per unit of volume, in Nissl preparations, of the degenerated LG, was expressed as a percentage of the mean number of the corresponding cells estimated in the normal LG on the same slide. The number of degenerating neurons decreased progressively. While 12 weeks following surgery a few isolated nerve cell nuclei could still be seen in the LG, by the end of the twenty‐fifth postoperative week the nucleus was practically devoid of neurons. The reaction of the astrocytes indicated a biphasic process—proliferation with subsequent reversal to an almost normal level. The oligodendrocytes and microglia multiplied at a somewhat slower rate, but remained far above the control values over a period of 50 postoperative weeks.