THE MECHANISM OF 1PN FORMATION AFTER IVF INCLUDING FEMALE AND MALE GENOMES

Abstract

Normal fertilization after in vitro fertilization (IVF) occurs in metaphase II oocytes by the fusion of a single sperm with the oocyte membrane. A sperm which has fused with the oocyte membrane sometimes forms an ooplasmic protrusion (FC: fertilization cone) and then forms a male pronucleus (PN). Shortly after PN formation, a female PN develops beneath the 2nd polar body (PB). However, 2.7-5.6% of fertilized zygotes are reported to exhibit only one PN (1PN). Diploid 1PN formation has been considered to be the result of the fusion of paternal and maternal PNs.