Studies on Eupyrene and Apyrene Spermatozoa in the Silkworm, Bombyx mori L. (Lepidoptera : Bombycidae) : I. The Intratesticular Behaviour of the Spermatozoa at Various Stages from the 5th-instar to the Adult

Abstract

Apyrene sperm bundles showed their first appearance from the testicular follicle into the vas efferens at 144 hours after pupation. The bundles were separated when they passed through the basement membrane. At 192 hours after pupation the majority of the separate apyrene spermatozoa was observed in the vas efferens. On the other hand, the eupyrene sperm bundles first appeared from the follicle into the vas efferens at 192 hours after pupation. At 240 hours after pupation (the day before emergence) the majority was observed in the vas efferens. Maintaining their bundle in the intact state, those eupyrene sperm bundles passed through the basement membrane with their tails ahead and were mixed with the separate apyrene spermatozoa.When the apyrene sperm bundles appeared from the follicle, the tissue of the basement membrane became rough in appearance and when the majority of the apyrene spermatozoa was accumulated in the vas efferens, the tissue began to recover its original state. Before the recovering of the tissue was completed, the eupyrene sperm bundles began to appear in the vas efferens and the tissue resumed a remarkable rough appearance again. From the above observation, it was suggested that the apyrene spermatozoa played an important role in facilitating the passage of the eupyrene sperm bundles through the basement mambrane.