COMPARATIVE ULTRASTRUCTURE OF THE PRIMARY NUCLEUS IN <i>BRYOPSIS</i> AND <i>ACETABULARIA</i>¹,²

Abstract

SUMMARY The fine structure of the primary nucleus in Bryopsis hypnoides was compared with that of the primary nucleus in Acetabularia calyculus and Batophora oerstedii. In Bryopsis the mature primary nucleus contains a peripheral reticulum composed of 4–6 layers of 200 A diameter fibrils. The nuclear membrane has numerous nuclear pores that are located adjacent to the openings in the layers of the reticulum. Each nuclear pore is constituted of peripheral globular elements and a central granule. Although pores of similar structure are present in the nuclear envelope of Acetabularia and Batophora , a fibrillar reticulum is absent.