Ultrastructure of the chromocentre region in salivary gland polytene nuclei of Drosophila hydei

It is well known that during the process of polytenization in salivary gland nuclei of Drosophila larvae, the heterochromatic centric and pericentric regions of different chromosomes fuse together to form the chromocentre. On the basis of condensation and other cytogenetic features, Heitz (1934) distinguished between the 'alpha' and 'beta'-heterochromatin in these nuclei. Electron microscopic studies have shown that there are two distinct types of heterochromatin organization in the chromocentre region in salivary gland polytene nuclei of D. melanogaster (Lakhotia and Jacob 1974; Lakhotia 1974). In the present paper, the ultrastructure of the chromo-centre heterochromatin in larval salivary gland nuclei of Drosophila hydei is briefly reported