Ultrastructure of the Male Accessory-Glands and Sperm Ducts of Cylindrotaenia-Hickmani (cestoda, Cyclophyllidea)

The ultrastructure of unicellular accessory glands (=prostate glands) and external male ducts of the cestode Cylindrotaenia hickmani are described. Accessory glands open into the lumen of the external common sperm duct (=external vas deferens). The gland cells contain abundant endoplasmic reticulum, Golgi bodies and secretory bodies, and have elongate necks that pierce the apical cytoplasm of the duct. Cell contact with the apical cytoplasm of the sperm duct is mediated by septate desmosomes. Accessory glands secrete spherical particles, with a diameter of approximately 70 nm, that adhere to spermatozoa. The roles of these accessory glands may relate to activity of the sperm or development of the female system after insemination. Paired sperm ducts arise from testes, and unite to form a common sperm duct. Each duct consists of a tubular anucleate cytoplasmic region which is supported by nucleated cytons that lie sunken in the parenchyma. The apical cytoplasm of the paired sperm ducts (=vasa efferentia) possesses apical microvilli and abundant mitochondria, but few other cytoplasmic features. The apical cytoplasm of the common sperm duct possesses sparse apical microvilli and numerous electron-lucent vesicles. The male gonoducts form an elongate syncytium which is markedly polarized along the length of the ducts. The ducts also display apical-basal polarity in that sunken nucleated cytons support the apical cytoplasm which in turn has distinct basal and apical domains