noun
- Plural of pronucleus; the haploid nucleus of a sperm or egg cell before fusion during fertilization.
Usage: biology; technical
Examples
- During fertilization, the male and female pronucleuses merge to form a diploid zygote.
- The egg's pronucleus and the sperm's pronucleus are both haploid before they fuse.
- Scientists observed the two pronucleuses approaching each other under the microscope.
- The pronucleuses must align properly for successful embryonic development to occur.