Spermatogenesis in Diploid Drones of the Honeybee

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Abstract
The process of spermatogenesis was investigated in 35 diploid honeybee drone pupae and compared with that in 15 haploid pupae. Altogether 25 013 chromosomes were counted, and 1200 measurements were made of cells in different stages of spermatogenesis. The spermatocytes of the diploids contained twice as many chromosomes and were twice as large as those of the haploids. The chromosomes did not pair or separate during metaphase I (prometaphase), when only a cytoplasmic bud was formed. The chromatids separated during metaphase II, and in anaphase a diploid set of chromosomes was visible. Only one spermatid and one polar body with chromatin were formed from one spermatocyte. Both the nucleus of the spermatid and the polar body were twice as large as in the haploids. The process of spermatogenesis in diploids was very similar to that in the haploids, with no reduction of the number of chromosomes, and thus the diploid drones produced diploid spermatozoa. This was probably caused by the homozygosity of the sex locus.