An autoradiographic study of gliogenesis in the rat lateral geniculate nucleus (LGN).

Rats pregnant for 14, 16, 18 and 20 days, as well as 1-, 3-, 7-, 12-, 16- and 21-day-old offspring, received a single injection of 3H]thymidine and were killed at postnatal ages of 22-27 days. An autoradiographic study of DNA synthesis revealed that proliferation of non-neuronal matrix cell precursors destined for the dorsal part of the lateral geniculate nucleus had already started by gestational day 14. Quantiative evaluation of the incidence of labelled cells revealed 2 peaks occurring in both groups of non-neuronal cells at postnatal days (PD) 7 and 16. It has been assumed that the accelerated production of ectodermally derived glial cells, observed towards PD 7, relfects the enhanced growth of the neuronal surface covered with glial cell processes, and that at PD 16 formation of myelin sheaths. Changes in the number of labelled cells of mesodermal origin in the course of development can probably be attributed to the rate of vasculogenesis of the studied region.