At the early stages of mammalian embryo development, Ca(2+) influences the processes of cleavage and differentiation. An important role in these processes is played by peptide growth factors. One of them, pentarphin, is a peptide growth factor similar to the central part of β-endorphin molecule and a fragment 369-373 of IgG heavy chain. We used fluorescent Ca(2+) indicators Fluo-3 AM and Fura Red AM. Pentarphin added to embryos in a concentration of 0.1 μM 1.5-2 fold increased intercellular Ca(2+) level in comparison with the initial level.