ACROSOMAL MORPHOLOGY AS A NOVEL CRITERION FOR MALE-FERTILITY DIAGNOSIS - RELATION WITH ACROSIN ACTIVITY, MORPHOLOGY (STRICT CRITERIA), AND FERTILIZATION IN-VITRO

Objective: To determine the relationships between sperm acrosin activi ty, sperm morphology evaluated according to strict criteria, visually observed acrosomal morphology, and IVF rates. Design: Prospective anal ytic study. Acrosin activity was determined on all semen samples toget her with a standard semen analysis. Emphasis was placed on sperm morph ology and especially a novel criterion viz acrosome morphology (acroso me index) as recorded with bright field microscopy. Setting: Universit y-based tertiary care center. Patients: Thirty-three couples undergoin g IVF or GIFT with two or more metaphase II ova inseminated in vitro. Main Outcome Measure: In vitro fertilization rates of inseminated ova. Results: Strong correlations were found between acrosome index, norma l sperm morphology, and IVF rates. An acrosome index cutoff value coul d be established at >10% normal acrosomes for IVF rates of greater tha n or equal to 50% (sensitivity and specificity = 100%) and an acrosin activity cutoff value at >18 mu IU/10(6) sperm. A multiple linear regr ession analysis showed that the acrosome index and acrosin activity ad ded a significant contribution to the explanation of the variation in the fertilization rates. Conclusions: A strong positive correlation wa s found between acrosome index and IVF rates. Although the numbers of the study are small, the results indicate that the acrosome index poss ibly may be regarded as an additional tool in the prediction of IVF ou tcome and especially may be of value in the group of men with severe t eratozoospermia, i.e., less than or equal to 4% morphologically normal spermatozoa.