Different methods of microanalysis (energy of wavelength dispersive X-ray spectrometry microprobes, ion microanalyser) combined with histochemistry, allowed us to analyse the cement of the tube and the main glands connected to the building organ of Sabellaria alveolata (L.). These methods clearly showed a mineral component of which the main elements are phosphorus, probably linked to the organic component, calcium, and magnesium, with some manganese and iron. The biomineral is produced by glandular cells having "heterogeneous spherulae." The quick hardening of this cement probably takes place independent of and before the quinonic tanning of the inner organic lining of the wall of the tube.

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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.