Methods of Measuring the Fertilizing Ability of Sperm

77 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.This thesis was concerned with finding methods of measuring the fertilizing ability of sperm that were more sensitive and precise than the methods commonly used, such as conception rate, non-return rate or litter size. When fertilizing ability is measured by one of these methods females are generally inseminated with sperm of a concentration that results in 90% or more fertilized eggs. Several experiments were conducted to determine if differences could be more easily detected when some other percentage of eggs was fertilized. The percentage of eggs fertilized was altered by changing either the concentration of sperm or the time of egg recovery. Female mice of ICR strain were induced to ovulate and inseminated with sperm from DBA/2N, CF1 or C57BL/6N males at 1 hour after ovulation. Eggs were recovered at various intervals after insemination. Eggs with a sperm in the perivitelline space or vitellus or with 2-cells were considered penetrated by a sperm. The results of these experiments indicated that fertilizing ability was best measured when approximately 50% of the eggs were fertilized. Fifty percent fertilized eggs could be obtained by manipulating either the concentration of sperm or the time of egg recovery.Mixed inseminations have been used to measure the comparative fertilizing ability of sperm. Females are inseminated with a mixture of sperm from two males and the proportion of offspring sired by each is determined. An experiment was conducted to compare the results of this method to the results of the methods described previously. Differences between strains appeared considerably greater when their sperm were mixed than when used seperately.An experiment was conducted to investigate a possible cause for differences among males in the percentage of eggs fertilized. The relationship between the number of sperm in the cumulus and the percentage of eggs penetrated was determined. The results demonstrated that unpenetrated eggs are associated with few sperm at the sight of fertilization.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD