The development of the diencephalon of the rainbow trout (Salmo gairdneri Richardson). Thalamus and hypothalamus.

This article describes a study of the development of the thalamus and hypothalamus of the rainbow trout from the embryo to the juvenile fish. The areas from which the various nuclei derived are reported together with the order of their appearance, the earliest being the nucleus geniculatus lateralis, the nucleus pretectalis, the nucleus of the torus lateralis hypothalami, the nucleus preglomerulosus and the nucleus diffusus of the lateral lobes, all of were beginning to be distinguishable in 9 mm embryos. The lateral lobes of the hypothalamus developed mainly after hatching, and medial regions generally developed later than lateral areas, though certain periventricular structures appeared very soon. Cell proliferation persisted in 35 mm juveniles, especially in the walls of the lateral and posterior recesses.