Annual cycle of the chromaffin cells of Triturus cristatus

Morphology of the chromaffin cells of Triturus cristatus during a complete annual cycle has been investigated. General ultrastructural characteristics are similar for all chromaffin cells, including numerous small mitochondria, well‐developed Golgi apparatus and rough endoplasmic reticulum with short cisternae. The primary difference among cells is the type of the chromaffin granules they posses. These are of two kinds: adrenalin (A) and noradrenalin granules (NA). Both types are simultaneously present in the chromaffin cells but with different ratios during the year. During December–January and May–August, NA granules largely prevail, while in September–November and February–April, A and NA granules are present in about equal quantities. The total quantity of catecholamine granules, however, is relatively constant throughout the year. These findings suggest that T. cristatus has a single type of chromaffin cell, the granule content of which varies according to different functional states. The catecholamines are apparently discharged by exocytosis.