title: Blastocyst development in co-culture: development and morphological aspects.
abstract: A retrospective study was undertaken to determine if initial culture conditions and embryo quality had an effect on subsequent blastocyst development in co-culture for cryopreservation. The apparent effects of freeze-thawing on blastocysts at the ultrastructure level were also observed. On day 3 of culture, embryos were categorized into two groups based on their morphological attributes. Results suggest that the initial culture environment of embryos up to day 3 (5- to 8-cell stage) did not affect the subsequent rate of blastocyst formation in co-culture. However, the initial embryo quality had an impact on blastocyst formation and quality. On day 5.5, 90% (60/67) of the optimal quality embryos (six to eight blastomeres with minimal or no fragmentation on day 3) had attained the blastocyst stage, which was greater (P < 0.01) than the 55% (31/56) observed with the sub-optimal embryos (five to eight blastomeres with 30-50% fragmentation on day 3). Furthermore, 66% (44/67) of embryos initially graded as optimal were suitable for cryopreservation, which was greater (P < 0.01) than attained with embryos of lesser quality (22/56; 39%). At the ultrastructural level, the polarized distribution of plasma membrane microvilli was retained, as was the integrity of the nuclear membrane following thawing.
authors.affiliation: Institute for Assisted Reproduction, Charlotte, NC 28207, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Wiemer
authors.forename: B
authors.initials: B
authors.lastname: Dale
authors.forename: Y
authors.initials: Y
authors.lastname: Hu
authors.forename: N
authors.initials: N
authors.lastname: Steuerwald
authors.forename: W S
authors.initials: WS
authors.lastname: Maxson
authors.forename: D I
authors.initials: DI
authors.lastname: Hoffman
mesh_terms: D001755:Blastocyst / Q000648:ultrastructure*; D015925:Cryopreservation; D046508:Culture Techniques; D005314:Embryonic and Fetal Development; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D012189:Retrospective Studies; D013997:Time Factors