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Browsing by Author "Yuan, Ye, committee member"

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    Development of a bison-specific embryo culture system through targeted supplementation of media with stage-specific growth factors
    (Colorado State University. Libraries, 2024) Acevedo Barriga, Carolina, author; Barfield, Jennifer P., advisor; Dawit, Tesfaye, committee member; Pinedo, Pablo, committee member; McCue, Patrick, committee member; Yuan, Ye, committee member
    In vitro embryo production (IVP) offers a practical genetic exchange method for bison herds, eliminating the need for live animal transport and reducing stress on the animals. While successful in cattle, IVP efficiency is lower in bison. This study aims to enhance bison embryo quantity and quality by supplementing IVP media with stage-specific growth factors. Thirteen growth factor receptors (GFRs) were screened in bison and bovine embryos, with six GFRs falling within acceptable ranges. Abattoir-sourced oocytes were used for IVP (4 replicates). GFR expression, notably IGFR2, BMPR2, FGFR1, and EGFR1, peaked in bison embryos at the zygote and 8-16 cell stages, with higher IL6 expression at the morula stage. Bovine embryos displayed highest expression of BMPR2, EGFR, and IGFR1 at zygote and 8-16 cell stages, and of FGFR1 and IGFR2 at zygote stages. Corresponding growth factors were incorporated into bison culture media based on GFR expression. Treatment evaluations, included EGF, IGF1, IGF2, IL6, BMP2, FGF1, and a combination of all GFs to bison culture media. Results revealed that the addition of BMP2 resulted in a decrease in cleavage rates. Notably, EGF, IGF1, and IGF2 enhanced blastocyst rates, with IGF1 significantly higher than the control. Subjective embryo qualitative evaluation showed an upward trend in the number of high quality expanded blastocysts, and lipid content decreased (IGF1) while cell count increased (IGF1, IL6, BMP2, FGF1) with growth factor supplementation. In conclusion, supplementing IVP media with GFs, particularly IGF1 at 50 ng/mL, significantly improved both quantity and quality of bison embryos. Application of IVP theology has advance the use of assisted reproductive technologies for bison, potentially benefiting other species.
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    Modeling human trophoblast development during the peri-implantation period using extended embryo culture
    (Colorado State University. Libraries, 2023) Logsdon, Deirdre Maria, author; Winger, Quinton, advisor; Krisher, Rebecca, advisor; Yuan, Ye, committee member; Tesfaye, Dawit, committee member; DeLuca, Jennifer, committee member
    During the peri-implantation period, a human embryo must transition from a pre-implantation stage blastocyst to a gastrulating embryonic disc surrounding by the primitive placenta. The primitive placenta at this time establishes contact, proliferates, invades, modulates the maternal immune system, and provides a primitive form of nutrients to the implanting embryo proper. Insights into this period have been largely stunted due to the ethical and technical challenges that accompany human embryo research. Studies using donated human embryos following fertility treatment are complicated by confounding infertility diagnoses and limited sample sizes. The development of the extended culture system has provided an avenue to functionally study the peri-implantation period. Further, by using a variety of models including mouse embryos, human embryos, and stem cell-derived blastoids in the extended culture system, researchers are finally able to begin to piece together the puzzle of the peri- implantation period. Here, our objectives were to demonstrate the utility of mouse models in modeling human trophoblast during peri-implantation extended culture, examine and summarize human development during peri-implantation in the context of confounding fertility diagnoses, compare human trophoblast in extended culture to other widely available regenerative trophoblast models, and determine to what extent blastoids are able to reflect human peri-implantation development and maternal-fetal crosstalk in extended culture. Further, we show that estrogen signaling in trophectoderm may be conserved between mouse and human embryos, aged embryos exhibit hindered growth in extended culture, peri-implantation trophoblast cells have unique transcriptional priorities, and the presence of endometrial stromal cells encourage fusion of syncytiotrophoblasts. Our studies both reinforce the significance of the extended culture system and lay the groundwork for future studies on early trophoblast and embryo development during peri-implantation.