pronuclear stage
Pronunciation: pro-NEW-klee-ar
The embryonic stage immediately after fertilization when male and female pronuclei are visible but have not yet fused.
Full Definition
The pronuclear stage represents the earliest stage of embryonic development, occurring 16-20 hours after fertilization when both the male and female pronuclei are clearly visible within the cytoplasm but have not yet undergone nuclear fusion. This stage is characterized by the presence of two distinct pronuclei and typically two polar bodies. Assessment of pronuclear morphology and number is crucial in IVF laboratories for determining normal fertilization and predicting embryo developmental potential.
Usage
Usage note: Often abbreviated as '2PN' in laboratory reports when referring to normal fertilization.
In Context
- "Embryo assessment at the pronuclear stage showed normal 2PN morphology in 12 of 15 oocytes." — Laboratory report
- "The pronuclear stage evaluation revealed several embryos with abnormal pronuclear patterns requiring disposal." — Clinical documentation