Testicular Changes of Honey Bee Drones,<i>Apis mellifera</i>(Hymenoptera: Apidae), During Sexual Maturation
Colby D. Klein, Ivanna V. Kozii, Sarah C. Wood, Roman V. Koziy, Michael W. Zabrodski, Ihor Dvylyuk, Ígor Médici de Mattos, Igor Moshynskyy, Ali Honaramooz, Elemir Simko
Abstract
The normal developmental anatomy and histology of the reproductive tract of the honey bee drone, Apis mellifera (Linnaeus, 1758), has been well documented. The post-emergence maturation changes of the accessory glands are likewise well understood, but the normal histological changes of the testicle undergoing physiologic atrophy are not well characterized. To address this knowledge gap, herein we describe the anatomy and sequential histological stages of normal testicular atrophy of drones sampled daily from emergence to sexual maturity in the spring (June) and early summer (July). Testicular histological changes during maturation are characterized by the following stages: I) conclusion of spermiogenesis; II) evacuation of spermatodesms from tubular lumens; III) progressive follicular cell atrophy, and IV) complete atrophy and collapse of testicular parenchyma. Tubular changes occur in a basilar to apical direction where segments closer to the vas deferens are histologically more mature than corresponding apical segments. In addition, the rate of testicular maturation was found to change with seasonal progression. This description of physiologic testicular atrophy should be useful for future studies investigating potential pathological effects of stressors on drone testes during sexual maturation.