[Radioautographic study of the developmental period of the cells of the supraoptic nucleus during mouse embryogenesis].

To study the time of cell origin in the supraoptic nucleus, double labelling with 3H- and 14C-thymidine was applied to the matrix cells of embryonic ependyma with intervals of 12, 24 and 48 hrs from the 9th day of gestation. The localization of the labelled cells was studied in the brain of the offspring using autoradiography. The labelling allowed to determine the time of the last division of the matrix cells, prior to their differentiation into neurosecretory cells. The neurosecretory cells forming the supraoptic nucleus were shown to arise mainly on the 11--13th day of embryogenesis. The cells originated on the 11th day were located only in the dorso-caudal parts of the nucleus. The most neurosecretory cells arise in the second half of the 12th day and are distributed all over the nucleus with the dorso-ventral (caudo-rostral) gradient. From the 13th day on the migration of the neurosecretory cells in the supraoptic nucleus sharply reduces but still persits until the 17th day. The glioblasts begin to migrate in the supraoptic nucleus from the 14th day on.