IVM media, oocyte diameter and donor genotype at RYR1 locus in relation to the incidence of porcine diploid oocytes after maturation in vitro

In vitro production of porcine embryos: current status, future perspectives and alternative applications

“…However, little is known about the mechanism that lies behind the meiotic arrest during IVM. It has been reported that, in pigs, this malfunction is neither related to oocyte diameter nor the composition of basic media or donor age but seems to be affected by genotype (Lechniak et al . 2005, 2007).…”

Altered microfilament dynamics contribute to the formation of diploid metaphase spindles in porcine oocytes which fail to reach the metaphase‐II stage during in vitro maturation

“…This status is morphologically similar to that of oocytes at the first meiotic metaphase (also known as the metaphase‐I (MI) stage) before the segregation of homologous chromosomes and therefore such oocytes were previously addressed as MI‐arrested ones (Kikuchi et al, 1999). However, later studies revealed diploid (2n = 38) sets of 2‐chromatid (monovalent) chromosomes (a status called “diploid MII” stage) among those porcine oocytes that failed to extrude 1PB during IVM (Lechniak et al, 2005, 2007; Sosnowski et al, 2003). This suggests that homologous chromosome segregation may occur in some oocytes which fail to extrude the 1PB.…”