Preliminary observations in in vitro development of equine embryo after ICSI

Abstract

The objective of this study was to perform intracytoplasmic sperm injection (ICSI) on in vitro matured equine oocytes and to improve in vitro embryonic development on Vero cells after activation of the microinjected oocytes with calcium ionophore. After maturation (23 or 40 h, 38.5 C, 5 % CO,), the cumulus-oocyte complexes were denuded, centrifuged and all oocytes exhibit- ing the first polar body were microinjected. ICSI was performed using fresh semen from three fertile stallions. Microinjected oocytes were activated with calcium ionophore A23187 (10 min, 10 pM) and cultured individually for 7 days on Vero cells in microdrops. In seven trials, 353 cumulus-oocyte com- plexes were matured and 103 oocytes were microinjected. Eight oocytes were sham microinjected. After ICSI, 85 oocytes (82.5 %) survived the sperm injection procedure. Among the 76 success- fully microinjected oocytes, 52 (68 %) were fertilized (two pronuclei, syngamy stage and cleaved ova). Sham microinjected oocytes were not activated. After in vitro culture, 35 ova (46 %) were cleaved 2 days after ICSI and early embryonic development was obtained (three embryos of 23 cells, 50 cells and more than 80 cells) 5 to 7 days after ICSI. © Inra/Elsevier, Paris. ICSI / equine / oocyte activation / co-culture / embryo development Rsum ― Dveloppement embryonnaire in vitro aprs ICSI dans l'espce quine : observa- tions prliminaires. L'objectif de ce travail tait d'tudier, aprs microinjection d'un spermato- zode dans le cytoplasme d'ovocytes de jument (ICSI) et activation par un ionophore calcique des ovo- cytes microinjects, le dveloppement in vitro des embryons ainsi obtenus sur un tapis de cellules Vro.