EVALUATION OF THE SPINDLE APPARATUS OF IN-VITRO MATURED HUMAN OOCYTESFOLLOWING CRYOPRESERVATION

The present study was conducted to determine if the cryopreservation o f immature human oocytes has a deleterious effect on the meiotic spind le following maturation in vitro. Oocytes were obtained in excess from in-vitro fertilization patients and divided into four groups, Groups 1 (n = 98) and 2 (n = 80) consisted of immature oocytes cryopreserved before or after maturation in vitro respectively, Groups 3 (n = 37) an d 4 (n = 9) served as nonfrozen controls and included oocytes matured in vitro and in vivo respectively. The meiotic spindle was identified after incubation in anti-tubulin monoclonal antibody (1 h, 37 degrees C) and fluorescein-conjugated goat anti-mouse immunoglobulin G (IgG) ( 1 h, RT). Chromosomes were counterstained with 4',6'-diamidino-2-pheny lindole. Following cryopreservation, group 1 oocytes demonstrated a 63 % survival rate and 68% maturation rate in vitro. In all, 58% of the o ocytes in group 2 survived the thaw. The number of oocytes with normal spindles in group 1 (81.0%) was not significantly different from cont rol groups 3 (83.8%) and 4 (88.9%), while the number of group 2 oocyte s with normal structures (43.5%) was significantly lower than groups 1 (P = 0.0004), 3 (P = 0.0002), and 4 (P = 0.025). These results sugges t that cryopreservation of the prophase I human oocyte does not signif icantly increase abnormalities in the resulting meiotic spindle.