Spindle And Chromosome Changes Of Human MⅡ Oocytes During The Incubation After Slow Freezing-Fast Thawing Procedure

Objective: Meiotic spindle destruction is one of the critical problems responsible for the low survival and vitality of the frozen-thawed metaphase Ⅱ (M Ⅱ) human oocytes. After thawing, it takes certain time for these oocytes to reconstruct the spindles before they are ready for fertilization. This study is designed to discover how long the meiotic spindles need to reorganize well.Material and method: 89 M Ⅱ oocytes of 17 consenting patients undergoing ovarian stimulated cycles were collected in the Reproductive Center of Shandong University and Shandong Provincial Hospital. 71 oocytes of 11 patients were cryopreserved with a 1.5mol/L 1,2-propanediol +0.3mol/L sucrose solution . After thawing, oocytes from the same patient were divided randomly into 3 groups and incubated at 37°C for 1,3,5 hours respectively before immunostaining of tubulin and chromatin and at last visualizing by confocal microscopy. 18 oocytes retrieved from 6 patients as control were immunostained without freezing.Result: 62 oocytes survived with a survival rate of 87.32%. 21 oocytes were incubated for one hour after thawing, and the proportions of oocytes exhibited normal spindle and chromosome configuration are 28.57% and 57.14% respectively. 20 oocytes incubated for 3 hours showed the proportions as 65% and 70% respectively. 21 oocytes for 5 hours were 66.67% and 71.43% respectively...