Decreased Spermatozoal Survivability Associated with Aberrant Morphology of the Ductuli Efferentes Proximales of the Chicken (Gallus Domesticus)1

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Abstract
The objective of this research were twofold: 1) to determine if decreased spermatozoal longevity, a previously reported heritable trait in chickens, was attributable to spermatozoal passage through the excurrent ducts, and 2) to document the morphology of the testicular excurrent ducts from affected roosters. Though spermatozoa were viable at ejaculation, as evidenced by their exclusion of ethidium bromide, fertility after intravaginal insemination of spermatozoa from affected roosters was less (p < 0.001) than that observed with spermatozoa from nonaffected controls, 37 ± 2.3 versus 58 ± 1.5%, respectively, over a 21-day egg-collection interval. In contrast, fertility after intramagnal insemination of testicular spermatozoa from affected roosters was equivalent (p > than 0.05) to that of nonaffected controls, 47 ± 2.2 versus 41 ± 3.6%, respectively. After intravaginal insemination, neither type of testicular spermatozoa fertilized oocytes. The ductuli efferentes proximales from affected roosters were characterized by a greater luminal cross-sectional area as well as a diminished height and number of longitudinal epithelial folds (p < 0.005). It was concluded that heritable decreased spermatozoal longevity in the chicken is not attributable to an inherent spermatozoal defect. Rather, the defect is acquired during passage of spermatozoa through the extragonadal ducts of the rooster.