The ability to measure an acrosome reaction in human sperm may lead to new diagnoses and therapy for male infertility. A number of techniques have been described, but none are routinely used in a clinical semen analysis. The objective of this research is to optimize the conditions for an indirect immunofluorescence assay using existing monoclonal antibodies, T6 an MHS-10, to quantitate acrosome reacted sperm. Assays will be developed for determining the acrosome status of a fresh ejaculate as well as for measuring the acrosome inducible population in a semen specimen. The assay will be optimized for minimal day to day and donor to donor variability. The indirect immunofluorescence assay also will be evaluated using an acrosome induction technique which has been extensively correlated with in vitro fertilization and pregnancy rates. If an acrosome reacted population can be consistently detected, the assay will be moved into clinical trials at Baylor College of Medicine to evaluate sperm from infertile patients.