Df(2R)achi¹ homozygotes (which is a deletion that creates two alleles achi¹ and vis^achi-1) are viable. Their males are completely sterile and females crossed to wild-type males exhibit a delay in egg laying. testes from homozygous males have a complete absence of mature sperm. Stages up to late spermatocyte are present but no meiotic stages can be seen. Df(2R)achi¹ testes exhibit a marked defect in the chromatin of mature primary spermatocytes (stages S5 and S6). While these cells are large and have the prominent nucleoli characteristic of this stage, the chromatin is condensed into tight central blobs normally observed only in later meiotic cells.