Intracellular pH changes during zona drilling.
OBJECTIVE
To investigate whether zona drilling of oocytes, a technique used to locally disrupt the zona pellucida, causes important changes in intracellular pH.


METHODS
In a first set of experiments, intracellular pH was measured during zona drilling of mouse oocytes, using pH-sensitive microelectrodes. In a second set of experiments human oocytes that failed to fertilize were used to measure intracellular pH during drilling. In these cells intracellular pH was measured using microfluorimetry with the pH-sensitive dye 2',7'-bis-carboxyethyl-5(6)-carboxyfluorescein.


RESULTS
In mouse oocytes intracellular pH dropped from 7.25 +/- 0.02 (mean +/- SEM) to 7.09 +/- 0.03 during zona drilling, followed by a recovery to pH 7.17 +/- 0.02 after 4 minutes (n = 20). In human oocytes, intracellular pH dropped over 0.36 +/- 0.10 pH units during drilling, followed by a recovery that was complete within 4 minutes (n = 14).


CONCLUSIONS
Zona drilling is associated with a significant cytoplasmic acidification both in mouse and human oocytes. This effect is perhaps related to the high incidence of cytoplasmic degeneration after zona drilling of human oocytes.
Depypere
H T
HT
University Women's Clinic, University Gent, Belgium.
Leybaert
L
L
D000818:Animals; D005260:Female; D005307:Fertilization in Vitro; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006801:Humans; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008839:Microelectrodes; D009865:Oocytes / Q000502:physiology*; D015044:Zona Pellucida / Q000502:physiology*
D005452:Fluoresceins; D005456:Fluorescent Dyes; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein