Ultrastructural identification of monoaminergic synaptosomes from one day old rat brain.

Synaptosomes from one day old and adult rat brain were studied. Specific cytochemical methods for demonstrating monoaminergic (MA) nerve endings were used. Permanganate fixation after preincubation with 5-OHDA or alpha-methyl-NA demonstrated MA synaptosomes. Their number was small in the adult (less than 1 %) and still smaller in the one day old rat brain. The MA synaptosomes from developing rats were different from the adult ones. The large amount of endoplasmic reticulum in developing synaptosomes suggests that granular vesicles are formed from endoplasmic reticulum in nerve endings.