In vitro development of chick hypothalamic neurosecretory cells.

The in vitro maturation of chick hypothalamic neurosecretory cells has been studied by the Golgi method and electron microscopy. Rotary cultures prepared from chick embryos aged 6, 8 and 10 days of development fail to assemble histotypic cultures; however, cultures prepared from older embryos, i.e. 12, 14 and 16 days of development, progressively exhibited more neurosecretory characteristics. It is interesting to point out that cultures prepared from 12-, 14- and 16-day-old chick embryos form complex surfaces composed of patches of glioepithelial cells alternating with zones containing neurosecretory nerve endings partially surrounded by glial processes. This particular distribution of the nerve endings seems to indicate that cytotypic hypothalamic neurons in rotary cultures deliver their products to the incubation medium; this interpretation is further reinforced by the observed exocytosis of the neurosecretory material within the external neuropile of histotypic cultures. Details of the neurosecretory cell maturation are given in the text.