EFFECT OF DIFFERENT COCULTURE SYSTEMS IN EARLY HUMAN EMBRYO DEVELOPMENT

The objective of this study was to examine the effects of different cu lture systems on the development of early human embryos in vitro, A to tal of 460 fertilized oocytes from 82 cycles of patients were transfer red into one of four systems: (1) into droplets of Ham's F10 medium 12% normal human serum (NHS); (2) co-cultured on a human granulosa mon olayer; (3) co-cultured with bovine oviductal epithelial cells (BOEC); or (4) co-cultured with bovine uterine epithelial cells (BOEC). The p ercentage of cleavage and the morphological appearance of embryos were recorded daily for 72 h in each system using an inverted phase-contra st microscope. The results showed that the proportions of the fertiliz ed oocytes which developed to the four-cell stage 48 h after retrieval were, by culture system: (1) 70% (84/120); (2) 74% (85/115); (3) 78% (91/117); and (4) 76% (82/108). At 72 h after retrieval, the proportio ns of the eight-cell stage were, by culture system: (1) 45% (38/84); ( 2) 62% (53/85); (3) 75% (68/91); and (4) 70% (57/82). We concluded tha t a higher proportion of fertilized oocytes developed to embryos at th e eight-cell stage in systems 2, 3 and 4 than in system 1. This indica tes the beneficial effect of co-culture of human embryos with granulos a cell, BOEC and BUEC monolayers, which may be due to various factors.