Fertilization and early embryology: Effect of different co-culture systems in early human embryo development

Abstract

The objective of this study was to examine the effects of different culture systems on the development of early human embryos in vitro. A total of 460 fertilized oocytes from 82 cycles of patients was transferred 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 monolayer; (3) co-cultured with bovine oviductal epithelial cells (BOEC); or (4) co-cultured with bovine uterine epithelial cells (BUEC). The percentage of cleavage and the morphological appearance of embryos were recorded daily for 72 h in each system using an inverted phase-contrast microscope. The results showed that the proportions of the fertilized 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 proportions 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 that a higher proportion of fertilized oocytes developed to embryos at the eight-cell stage in systems 2, 3 and 4 than in system 1. This indicates the beneficial effect of co-culture of human embryos with granulosa cell, BOEC and BUEC monolayers, which may be due to various factors.