Submitted to: Journal of Reproduction and Fertility
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/10/2001
Publication Date: 1/1/2002
Citation: King, L.M., Brillard, J.P., Garrett, W.M., Bakst, M.R., Donoghue, A.M. Segregation of sperm within sperm storage tubules of the fowl and turkey hen. Reproduction 123:79-86, 2002. Interpretive Summary: Hens are able to fertilize a succession of eggs after a single insemination of semen due to their capacity to store sperm in the lower portion of the oviduct. Located at the juncture of the uterus and vagina (UVJ) are cell lined tubular invaginations which are continuous with the cells of the UVJ lumen. These unique structures are referred to as sperm storage tubules (SST). How sperm survive within and escape from the SST is not known. Using contemporary methods of microscopy and improved staining technology, we were able to show for the first time that sperm in successive inseminations randomly fill the SST and do not stack upon each other in the same SST. Thus, the theorized last male precedence, that is, the sperm from the last male or last insemination are the first to fertilize an ovum, does not appear to be due to the stratification of sperm within the SST. This fundamental information will benefit other scientists investigating the basis of paternity (sperm competition) in commercial flocks as well as in non-domestic bird species.
Technical Abstract: In avian species, sperm reside in the oviduct for prolonged periods in specialized structures known as sperm storage tubules, but little is known regarding the relative distribution of sperm in the tubules following successive inseminations. To evaluate sperm competition, we determined the staining efficacy of various fluorescent dyes with fowl and turkey sperm. Stained and unstained sperm were then inseminated at different intervals t observe their spatial distribution within the storage tubules. It was found that several novel fluorescent lipophilic tracers that successfully stain mammalian sperm either did not stain fowl or turkey sperm or greatly impaired sperm motility. In contrast, Hoechst 33342 readily stained sperm nuclei (fowl: 25 nM; turkey: 77 nM) within 4 hr without inhibiting motility or affecting fertility or hatchability. To study sperm entry and storage within the tubules, hens were tandemly inseminated with equal numbers of stained or unstained sperm 24 hr apart and sacrificed 24 hr after the fina insemination. Oviducal mucosa containing sperm storage tubules was removed, and individual tubules were classified as empty, containing stained sperm, unstained sperm, or containing mixed (both stained and unstained) sperm. Our results indicated that sperm from two different inseminations generally segregate into different storage tubules in both fowl and turkey hens. Storage tubules containing mixed populations of sperm were found in 4% of the fowl and 12% of the turkey tubules examined. Thus, the theorized last male precedence does not appear to be due to the stratification of sperm within the tubules.