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Colorado State University, Fort Collins 80521
Abstract
Thymidine methyl- [3H] was injected into the spermatic arteries of eight stallions and radioactive spermatozoa in ejaculated semen were detected by liquid scintillation counting and autoradiography. Minimal time for spermatozoal transit through the excurrent ducts averaged 4.9 days, while the average time was estimated to be between 7.5 and 11.0 days.
The extra-gonadal sperm reserves (EGR) of stallions ejaculated daily and sacrificed 24 hr. after the last ejaculation were 58.6 billion (109) spermatozoa of which 88% were located in the epididymides. The number of spermatozoa located in the caudae accounted for 61% of the total spermatozoa in the epididymides. A sufficient number of spermatozoa were located in the ductuli deferentia and ampullae to account for one ejaculate of semen. Epididymal sperm reserves and EGR were correlated (P< .05) with total testis weight (0.81, 0.70), daily sperm production (DSP) (0.71, 0.70), and daily sperm output (DSO) (0.74, 0.68), respectively.
1 This investigation was supported in part by grants-in-aid from American Breeders Service; Cryenco; and the National Association of Animal Breeders.
2 Portions of these data were from a thesis submitted by M. R. Gebauer to the Graduate Faculty of Colorado State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
3 Present address: Universal Semen Service, Ltd., Box 910, Cardston, Alberta, Canada.
4 Animal Reproduction Laboratory, Department of Physiology and Biophysics.
5 Visiting Scientist, Agriculture Canada, Research Station, Brandon, Manitoba, Canada.
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