The ultrastructural localization of lysosomal acid hydrolases in developing oocytes of the common marine mussel Mytilus edulis.

Azo dye techniques were used to investigate the ultrastructural localization of lysosomal acid hydrolases in ovarian oocytes of the common marine mussel Mytilus edulis. The enzymes were arylsulphatase, beta-glucuronidase, nonspecific esterase, N-acetyl-beta-hexosaminidase and acid phosphatase. For arylsulphatase, the azo dye technique was compared with an alternative method using nitrocatechol sulphate as the substrate and barium as the capturing ion. Activity of all the enzymes was found to be associated with the yolk granules and with pinocytotic phenomena which were observed along the basal membrane of developing oocytes. Activity was also found to be associated with resorption of atretic oocytes.