The Hemizona Assay: A Simplified Technique
The hemizona assay is an important diagnostic tool in assessing human sperm fertilizing potential. Previous hemizona assay results have proven that this functional test is a good predictor of fertilization in vitro and can be used in clinical practice to supply additional information in male factor subfertility cases. The objective of this study was to compare two methods for cutting human zona pellucida into equal halves (manual handcutting versus micromanipulation) in order to examine the necessity of an expensive micromanipulator in performing this assay. Comparable results for recovery rate, diameter size of the hemizonae, and sperm binding were achieved with both methods. According to these results, the use of an expensive micromanipulator is not essential in performing the hemizona assay.
An in vitro test of sperm function in which a human zona pellucida is divided in half and one half is incubated with sperm from a donor known to be normal and the other half with sperm from the patient being tested. The number of sperm bound to each half is calculated, and that from the patient’s sperm is divided by that from the donor’s sperm. A figure of less than 0.60 indicates abnormal patient sperm.
Characterized antihuman sperm monoclonal antibodies from mice were evaluated using the hemizona assay (HZA) to determine whether sperm: zona binding was effected. The seven monoclonal antibodies were characterized using human sperm in agglutination, immobilization, and penetration assays. Semen was provided by four fertile men and used in the HZA to determine if the presence of a monoclonal antibody would affect tight binding of the sperm to the zona pellucida. Pre-incubation of MA-14 for 1 h with the sperm induced a 33–54% reduction of the number of tightly bound sperm. This antibody reacts to an antigen located on the acrosome and midpiece. Experiments in which there was no pre-incubation of the antibody with sperm, resulted in no significant reduction in the number of sperm bound in the HZA. These findings suggest that an anti-human sperm antibody produced in mice can modulate sperm: zona binding. Reduction in zona binding could indicate a cause of immune-related infertility and this test may be useful in selecting an antigen for contraceptive vaccine development.
