Kinetic of cortical reaction induced by Sr2+ and ionomycin in ovulated and in vitro matured oocytes

CAPPA AI; DE BLAS G; DE PAOLA MM; MAYORGA L; MICHAUT M.

Congreso; L Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2014

Meiosis progression from metaphase II to embryo development requires oocyte activation, a set of events triggered by spermatozoa. One of these processes is cortical reaction, which consists in exocytosis of small vesicles called cortical granules and is responsible to block polispermy. In vitro maturation is used in assisted reproduction; however it is unknown how it affects oocyte activation and embryo development. In this work we compare the kinetic of cortical reaction stimulated by SrCl 2 and ionomycin between ovulated and in vitro-matured oocytes. Ovulated oocytes were collected from ampulla after PMSG-hCG stimulation. Immature oocytes were obtained from ovaries after PMSG stimulation and in vitro-matured in G-IVF Plus (Vitrolife) media during 16 h. Cortical reaction was parthenogenetically activated in both cell types, ovulated and in vitro matured oocytes, in the presence of lens culinaris agglutinin (LCA)-FITC for labeling of cortical granule´s exudate. Epifluorescence images were collected (1frame /minute during 60 minutes) and recorded on a LUCA-R EMCCD camera. After each experiment, cells were fixed and cortical granules were stained with LCA-rhodamine and quantified using Image J program. Our results show that cortical reaction triggered by SrCl 2 and ionomycin have different kinetic patterns and suggest that in vitro maturation affect the kinetic of cortical reaction.