polytene chromosomes resulting in typical reticular endopolyploid nuclei is normal to salivary gland nuclear development in many Cecidomyiid larvae. Sharp differences in the degree of chromatid conjugation may be related to tissue-specific features of cells. In many dipteran species, polytene chromosomes of the classic type are detected in the salivary gland cells. However, they are identified in the ovarian nurse cells in only a few species; in other species ovarian nurse cell nuclei are highly polyploid and reticular, i.e. they show cryptic polyteny.