Coculture of In Vitro Fertilized Bovine Embryos with Oviductal Epithelial Cells Originating from Different Stages of the Estrous Cycle

bovine embryos derived from in vitro fertilization procedures were cocultured in vitro with oviductal cells obtained from heifers between d 4 and 6 or d 14 and 16 of the estrous cycle. In addition, proteins secreted by oviductal cells isolated between d 4 and 6 or d 14 and 16 of the cycle were monitored. Embryos (2- to 4-cell) were incubated in Tissue Culture Medium-199 with 10% fetal bovine serum with or without oviductal cells at 39°C for 10 d following in vitro insemination. There were more morulae, blastocysts, and hatched blastocysts following coculture with oviductal cells than with culture in medium alone. However, no differences were noted in embryo development following coculture with oviductal cells obtained between d 4 and 6 or d 14 and 16 of the estrous cycle. Also, no differences were detected in the amount of [35S]methionine-labeled proteins secreted by oviductal cells isolated from different days of the estrous cycle. These results indicate that oviductal epithelial cells isolated from early and late luteal phases of the estrous cycle will effectively support early embryonic development following prolonged in vitro culture. © 1992, American Dairy Science Association. All rights reserved

Abnormal Early Cleavage Events Predict Early Embryo Demise: Sperm Oxidative Stress and Early Abnormal Cleavage

Human embryos resulting from abnormal early cleavage can result in aneuploidy and failure to develop normally to the blastocyst stage. The nature of paternal influence on early embryo development has not been directly demonstrated although many studies have suggested effects from spermatozoal chromatin packaging, DNA damage, centriolar and mitotic spindle integrity, and plasma membrane integrity. The goal of this study was to determine whether early developmental events were affected by oxidative damage to the fertilizing sperm. Survival analysis was used to compare patterns of blastocyst formation based on P2 duration. Kaplan-Meier survival curves demonstrate that relatively few embryos with short (<1 hr) P2 times reached blastocysts, and the two curves diverged beginning on day 4, with nearly all of the embryos with longer P2 times reaching blastocysts by day 6 (p < .01). We determined that duration of the 2nd to 3rd mitoses were sensitive periods in the presence of spermatozoal oxidative stress. Embryos that displayed either too long or too short cytokineses demonstrated an increased failure to reach blastocyst stage and therefore survive for further development. Although paternal-derived gene expression occurs later in development, this study suggests a specific role in early mitosis that is highly influenced by paternal factors