![]() ![]() Altogether, the core and ancillary factors form a cross‐regulated network, also known as the developmental or Oct4‐centric module, which buffers against pro‐differentiation cues and stabilises the undifferentiated ESC state (Dejosez & Zwaka, 2012 Hackett & Surani, 2014). Nanog, Esrrb, Klf4, Prdm14, Tbx3, Tfcp2l1 and Nr0b1). ![]() Similar to the naïve epiblast, ESC express the core pluripotency transcription factors, namely Oct4 and Sox2, and a set of so‐called “ancillary” transcription factors (e.g. The pluripotent properties of the epiblast are captured in vitro by embryonic stem cells (ESC), which are derived from blastocyst‐stage embryos. At the same time, the epiblast transforms from a simple ball of cells into a polarised epithelium (Bedzhov & Zernicka‐Goetz, 2014 Fan et al, 2020), where during the next days the body axes are laid down and differentiation into somatic lineages is initiated. Within 24 h, between E4.5 and E5.5, a burst of cell proliferation transforms the blastocyst into a post‐implantation conceptus (egg cylinder) (Govindasamy et al, 2019). The TE mediates direct contact with the maternal tissues and initiates the implantation of the embryo into the uterine wall. The blastocyst consists of a ball of naïve pluripotent cells (epiblast) surrounded by two extraembryonic tissues: the primitive endoderm (PE) and trophectoderm (TE). Cell fate decisions establish the first lineages, which self‐organise by embryonic day four and a half (E4.5) into a hollow‐shaped blastocyst. After fertilisation, the newly formed murine embryo undergoes several rounds of cleavage divisions in which progressively smaller cells (blastomeres) are generated while the total embryo volume stays constant.
0 Comments
Leave a Reply. |