[Ultrastructure of the rat locus coeruleus during early ontogeny].

Electron microscopic studies have been made on the development of the blue spot in 18-day foetuses as well as in 1-, 5-, and 12-day Wistar rats. Cellular bodies of the neurones in the blue spot are not distinguished by the intensive maturation, which is typical for the axons, the latter with respect to their length and spatial distribution being similar in 12--15-day foetuses and adult rats. During prenatal and early postnatal periods, ultrastructural indices were found which indicate the existence of the intensive transport of substances across the hemato-encephalic barrier. The existence of centripetal, i. e. towards the cells of the blue spot, transport of substances at early ontogenesis is suggested.