Development of neurotensin-immunoreactive nerve cells in organotypic cultures of embryonic rat spinal cord.

Neurotensin was localized by the indirect immunofluorescence method in developing organotypic cultures made from slices of the lumbar spinal cord of rat embryos (14-17 days gestation). Less than half of the cultures contained fluorescent cells, and in these specific immunofluorescence was confined to groups of neurones situated in the dorsolateral region of the explants. The neurones became morphologically fully developed after 21 days in culture. Their axons grew up to 1.7 mm in length and travelled within fibre bundles which were oriented around the circumference of the explant. The axonal growth patterns of spinal neurotensin-immunoreactive neurones in tissue culture suggest that they may project over relatively long distances in the rat spinal cord in situ.