The most vulnerable stage of embryogenesis is the early embryonic period. It is here that natural selection for viability takes place, and it is here that the highest percentage of losses is observed - nature checks the viability of the embryo before allowing it to implant and begin to form a body. Solving the applied aspects of reproduction is closely related to the study of embryogenesis and the search for stimulating factors that target specific processes that determine the fate of the embryo and its potential for implantation at the blastocyst stage. In a model of early mouse embryos, premature embryo compactification was detected in the early stages of development in the presence of calcium ionophore A23187 (1.0 μM). Morphological signs of compactification appear 2 min after the addition of the ionophore and are accompanied by an increase in the concentration of cytosolic calcium (3.5 times). At the same time, the visible boundaries between the blastomeres disappear, and their contact area increases, which normally occurs in mammals at the late 8-cell stage. The observed effect under the influence of A23187 is reversible: after removing the ionophore from the environment, the morphology of the embryos is partially restored within 20-30 minutes. It has also been shown that A23187-induced compactification in the early stages stimulates in vitro development processes. In embryos that have been pretreated with an ionophore, the rate of cavitation increases, and hatching occurs faster compared to embryos that have not been exposed to A23187. It is concluded that a short-term sharp increase in intracellular calcium in the early stages of development is an incentive for triggering primary morphogenetic processes with the participation and control of the calcium-dependent phosphoinositol signaling cascade. Inhibition of the main components of phosphoinositol signaling leads to a delay in the onset of embryo cavitation, a dose-dependent decrease in the rate of cavitation or lack thereof when using a phospholipase C blocker, as well as a delay in the blastocyst in zona pellucida, which may indicate the inability of the embryo to implant in the uterus and continue its development.
Pokhlichenko et al. (Thu,) studied this question.