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.
