Cell differentiation events in pre-implantation mouse and bovine embryos

Abstract

Early mammal embryogenesis starts with oocyte fertilization, giving rise to the zygote. The events that the newly formed zygote surpasses are crucial to the embryo developmental success. Shortly after activation of its genome, cells of the embryo segregate into the inner cell mass (ICM) or the trophectoderm (TE). The first will give rise to the embryo while the latter will become the placenta. This first segregation involves cellular and molecular processes that include cell polarity linked to intracellular pathway activation, which will regulate the transcription of trophectoderm-related genes. Then, cells of the ICM undergo the second event of mammalian cell differentiation, which consists of the separation between epiblast (EPI) and hypoblast or primitive endoderm (PrE). This second segregation involves paracrine signaling, leading to differential expression of key genes that will dictate the fate of the cell. Although these processes are described in detail in the mouse, recent studies suggest that the bovine embryo could also be an interesting model for early development, since there are differences to the mouse and similarities with early human embryogenesis. In this review, we gathered the main data available in the literature upon bovine and mouse early development events, suggesting that both models should be analyzed and studied in a complementary way, to better model early events occurring in human development.

Heterozygosity and homozygosity regions affect reproductive success and the loss of reproduction: A case study with litter traits in pigs

“…The expression level of CCDC91 , MACF1 , MFSD2A , EPC2 , and MBD5 has a significant fluctuation during the development of early embryo, but showed different trends in human, pig, and mouse. The phenomenon was consistent with previous studies, which stated that the molecular mechanisms of embryonic development shared many similarities, but also several marked differences in mammals [90] , [91] . In addition, the infants born to GDM females had reduced size at birth and persisting reductions in adiposity [92] .…”

The Centriole’s Role in Miscarriages

“…Additional similarities identified between bovine and human early embryogenesis are absent in mice ( Carreiro et al, 2021 ). Recently, it was reported that horses, whose sperm also have two centrioles, suffer from a high rate of aneuploidy in naturally occurring pregnancies ( Shilton et al, 2020 ).…”

Domínios ICRs 1 e 2 de bovinos no período pré-implantação: expressão, perfil da metilação do DNA e suas associações com a reprogramação epigenética

“…Já o segundo aumento da expressão deste gene durante o desenvolvimento embrionário vai de acordo com a sua função, uma vez que ele é um dos responsáveis pela primeira diferenciação celular que ocorre no embrião. Sabe-se que entre os estadios de mórula e blastocisto é iniciada a cavitação da blastocele e a diferenciação nas duas primeiras linhagens celulares, a MCI e TE (BERG et al, 2011;BÓ;MAPLETOFT, 2013;CARREIRO et al, 2021). Apesar do OCT4 ser fundamental para a diferenciação celular, sua ausência não é o suficiente para impedir o desenvolvimento embrionário.…”