Synthèse et exocytose de chlorocruorine et mise en réserve du fer par le tissu périvasculaire d'un annélide polychète

Abstract

The perivascular tissue of Sabella pavonina, a layer of brown cells covering ventral and lateral vessels, is characterized by three types of distinct inclusions in the cells: chlorocruorin vacuoles, ferritin particles and granules, and vacuoles containing both chlorocruorin and ferritin. The crystallization of chlorocruorin in trans-Golgian vesicles and the gathering of these into vacuoles suggests that this tissue is involved in the chlorocruorin synthesis and indicates that the terminal stage of this synthesis occurs in the Golgi apparatus. The basolateral exocytosis of this respiratory pigment in intercellular spaces and its transit to the lumen of the vessels are revealed. Alternating changes in chlorocruorin and ferritin contents of chloragocytes linked to ultrastructural variations in these cells, as observed in many sabella, led to the conclusion that the perivascular tissue play a role in both chlorocruorin synthesis and temporary iron storage.