Definition of Morphokinetic Events

Morphokinetic eventDefinition
tPNappearanceTime at which pronuclei formation can be first be identified
tPNfadedTime at which both pronuclei have faded
tnTime from insemination to completion of division to n cells
tSCTime from insemination to when the first cells of the embryo begin to compact
tMTime from insemination to formation of a morula, where all cells have compacted and cell membranes are unclear
tSBTime from insemination to start of blastulation, when the first sign of a cavity formation between two cells is visible
tBTime from insemination to formation of a full blastocyst; when the blastocoele cavity fills the embryo with less than 10% increase in its diameter
tEBTime from insemination to expanded blastocyst; when the blastocyst has increased in diameter by more than 30% and the zona pellucida has started to thin
THBTime from insemination to hatching blastocyst, when the trophectoderm herniation through the zona pellucida is first observed
Direct cleavageDirect or rapid (<5hours) cleavage from 1 to 3 or from 2 to 5 cells