Physiological induction of the acrosome reaction in human sperm: validation of a microassay using minimal volumes of solubilized, homologous zona pellucida.
OBJECTIVE
To develop a method that could accommodate microvolumes of solubilized human zona pellucida (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. An approximately 30% level of acrosomal exocytosis was induced with 2.5 ZP/microliter in 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.
Franken
D R
DR
Department of Obstetrics and Gynaecology, University of Stellenbosch, Tygerberg, South Africa.
Bastiaan
H S
HS
Oehninger
S C
SC
D020101:Acrosome Reaction / Q000187:drug effects / Q000502:physiology*; D001681:Biological Assay / Q000379:methods*; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D005260:Female; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D012995:Solubility; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*; D015044:Zona Pellucida / Q000737:chemistry / Q000502:physiology*
D007476:Ionophores; D002118:Calcium