Masters Theses

Date of Award

12-2021

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Daniel J. Mathew

Committee Members

J. Lannett Edwards, Kyle J. McLean, Liesel G. Schneider

Abstract

In vitro produced (IVP) bovine embryos provide enhanced genetic value and a means for studying early embryonic development. However, IVP embryos are developmentally compromised and are lower quality compared to in vivo derived (IVD) embryos. Consequently, after transfer pregnancy rates from IVP embryos are consistently lower, as they exhibit the highest amounts of pregnancy failure during the early embryonic phase (prior to day 28). Progesterone (P4) has been shown to influence bovine endometrial epithelial (EPI) and stromal fibroblast (SF) cells to secrete developmentally important molecules that promote early embryo development and conceptus elongation. However, IVP embryos are not exposed to these factors until Day 7 whereas IVD embryos gain exposure on Day 4, when the developing embryo begins migration out of the oviduct and into the uterus. Our hypothesis is that P4 stimulated bovine endometrial EPI and SF cell conditioned media will improve IVP bovine embryo development rate and quality by Day 8 of development compared to non-cell conditioned media. The first objective of this study includes observing the effect of dose dependent P4 treatment on isolated bovine uterine EPI and SF cells through expression of genes involved in luteolytic pathways, solute-like carrier transporters and growth factors. The second objective is to assess the effect of P4 stimulated bovine endometrial cell conditioned media on IVP bovine embryos, assessing development rate, morphologic quality, and expression of developmentally important genes that indicate embryo quality. The first study identified cell-specific expression of certain histotroph genes and P4 regulated genes between uterine EPI and SF cells. The second study illustrated that while IVP bovine embryos developed better in KSOM, evidence still presents future implications for improving IVP bovine embryo culture systems using endometrial cell conditioned media. Improving IVP embryo cultures systems along with a deeper understanding of the maternal environment will enhance IVP embryo production and quality.

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