Ultrastructure of the regenerating growth cones of catecholamine nerve terminals in rat hypothalamic nuclei after 5,7-dihydroxytryptamine administration.

Ultrastructure of the regenerating growth cones of catecholamine axons is examined in the paraventricular nucleus and median eminence of the rat. Growth cones are observed during 1 to 4 months, and most frequently at 2 months, after the administration of 300 microgram of 5,7-DHT in the lateral ventricle. The growth cones of catecholamine axons are characterized by an accumulation of branching smooth endoplasmic reticula which contain dense material.