Physiological induction of the acrosome reaction in human sperm: validation of a microassay using minimal volumes of solubilized, homologous zona pellucida.
OBJECTIVE
The objective was to develop a method that could accommodate microvolumes of solubilized human (ZP) and sperm for assessing the induction of the acrosome reaction.


METHODS
A microassay using 1 microliter of 2.5, 1.25, 0.6, 0.3, and 0.125 ZP/microliter incubated with 1 microliter of a highly motile sperm suspension for 60 min. As a control and parallel to the microassay a standard acrosome reaction technique was performed.


RESULTS
No significant differences were observed between the percentage acrosome-reacted sperm reported by the two assays under basal conditions (spontaneous) or after induction with a Ca2+ ionophore or solubilized ZP. At a ZP concentration of 0.6 ZP/microliter, the percentages of acrosome-reacted spermatozoa in both techniques were significantly higher compared to the spontaneous acrosome reaction results, namely 18% and 17%, compared to 10% and 10%, respectively. Approximately a 30% level of acrosomal exocytosis was induced with 2.5 ZP/microliter both methods.


CONCLUSIONS
This newly devised microtechnique is easy and rapid to perform, is repeatable, and facilitates the use of minimal volumes of solubilized human ZP (even a single ZP) for assessment of the inducibility of the acrosome reaction of a homologous sperm population.
Department of Obstetrics and Gynaecology, University of Stellenbosch, Tygerberg, South Africa.
D R
DR
Franken
H S
HS
Bastiaan
S C
SC
Oehninger
D020101:Acrosome Reaction; D002118:Calcium / Q000378:metabolism; D005260:Female; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*; D015044:Zona Pellucida
D005456:Fluorescent Dyes; D007476:Ionophores; D016650:Fluorescein-5-isothiocyanate; D002118:Calcium