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Embryo development in cattle and interactions with the reproductive tract

Lonergan, P., Sánchez, José María, Mathew, Daniel J., Passaro, Claudia, Fair, Trudee
Reproduction, fertility, and development 2019 v.31 no.1 pp. 118-125
blastocyst, cattle, cattle production, conceptus, early development, embryogenesis, embryonic mortality, hatching, luteolysis, oviducts, pregnancy, production technology, profitability, reproductive efficiency, uterus
Embryo mortality is a major contributor to poor reproductive efficiency and profitability in cattle production systems. Coordinated interaction between the developing embryo or conceptus and the maternal reproductive tract is essential for pregnancy establishment in mammals. Up to the blastocyst stage, the embryo can grow in the absence of contact with the oviduct or uterus; however, conceptus elongation after hatching and before implantation, a characteristic of ruminant early development, is entirely maternally driven and is essential to ensure that sufficient quantities of interferon-τ (IFNT) are secreted by the developing conceptus to abrogate the mechanisms that bring about luteolysis. Surprisingly, many questions, such as the threshold level of IFNT required for pregnancy maintenance, remain unanswered. Failure of the conceptus to elongate undoubtedly results in embryonic loss and is thus believed to contribute greatly to reproductive failure in cattle.