In mammalian development, the embryo which is in the process of compaction, involves a progressive flattening of blastomeres against each other with the consequence that the embryos assumes a spherical shape. This stage happens in the first
differentiation.
The present study was aimed to examine the involvement of other metal ions in compaction by treating with various divalent cations in the absence of Ca++.
When 8-cell embryos were cultured in Ca++ -free medium for 24hrs, they developed to 16-cell stage but did not compaction, and degenerated after 48hrs of culture. Embryos were cultured in Ca++-free medium for 24hrs and then transferred to the
control
medium showed the normal compaction afterwards.
When 8-cell embryos were cultured in the presence of Ni++, known as a Ca++ inhibitor, they cleaved to 16-cell stage but did not compact in the absence of Ca++. On the other hand, embryos cultured in the media containing both Ca++ and Ni++
developed
normally so that they underwent compaction during culture for 48hrs. However, they failed to hatch during further 24hrs in the same medium, indicationg that Ni++ may exert some harmful effects. Embryos grow in the control medium that contained
Ca++
but
not Ni++, developed to the hatched blastocysts.
The treatment with Cd++ 10E-1, 10E-2μM, Mn++ or Ba++ 10, 100, 1000μM in Ca++-free medium, respectively, inhibited compaction and embryonic degeneration began as in Ca++-free medium.
When 3, 5, 10mM of Sr++, known as a substitute for Ca++ in cell, was added to Ca++-free medium, respectively, compaction was induced unlike the above metal ions. Embryos were cultured in Sr++ developed to blastocysts, but failed to hatch after
72hrs and
degenrated. On the other hand, when embryos were cultured in 3, 5, 10mM of Sr++ but in Ca++-free medium for 24hrs respectively and then transferred to the control, they showed the similar development as that in the control.
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