Ultrastructure and Differentiation of Hydrodictyon Reticulatum III. Formation of the Vegetative Daughter Net

Abstract

Vegetative zooids of H. reticulatum, produoed by cleavage of parental ooenobial oytoplasm, linked together within their parental oell walls to form oylindrioal nets oharaoteristio of this alga. A oonspiouous feature of net-forming zooids were bands of miorotubules underlying the plasmalemma. An active role is proposed for these miorotubules in the ordered linking of the zooids. Amorphous material, presumably adhesive, was seen only in interoellular spaces between aggregating zooids. Following adhesion of the zooids, eaoh one usually linking with four others, their flagella were retraoted and both flagellar miorotubules and basal bodies disintegrated. Centrioles arose de novo on the nuolear envelope of eaoh cell at the time of deposition of a bilayered wall.