BACKGROUND The clinical efficacy of the current methods used for cryopreservation of metaphase II human oocytes is low. Meiotic spindle disorders are thought to be largely responsible for this situation. METHODS Supernumerary fresh metaphase II human oocytes were cryopreserved in 1,2-propanediol with 0.1 M sucrose using a slow freezing/rapid thawing programme. Meiotic spindles were analysed i...

INCENP and aurora-B kinase are two chromosomal passenger proteins that are thought to play key roles in coordinating chromosome segregation with cytokinesis in somatic cells. Here we have analyzed their subcellular distribution, and that of phosphorylated histone H3, and the timing of their relative appearance in mouse spermatocytes during both meiotic divisions. Our results show that in mitoti...

Fertilization of metaphase II-arrested mouse eggs results in resumption of meiosis and a decrease in both cdc2/cyclin B kinase and MAP kinase activities; the decrease in cdc2/cyclin B kinase activity precedes the decrease in MAP kinase activity. Cycloheximide treatment of metaphase II-arrested mouse eggs also results in resumption of meiosis but bypasses the fertilization-induced Ca2+ transient...

Cohesin maintains sister chromatid cohesion until its Rad21/Scc1/Mcd1 is cleaved by separase during anaphase. DNA topoisomerase II (topo II) maintains the proper topology of chromatid DNAs and is essential for chromosome segregation. Here we report direct observations of mitotic progression in individual HeLa cells after functional disruptions of hRad21, NIPBL, a loading factor for hRad21, and ...

Butyrolactone I (BL I), a potent and specific inhibitor of cyclin-dependent kinases, was shown to block germinal vesicle breakdown (GVBD) in porcine oocytes in a concentration-dependent manner. GVBD was almost totally inhibited over the course of 44 h of culture when 100 pM BL I was included in TCM 199 containing either 3 mg/ml BSA or 5 % fetal calf serum (FCS). In contrast, 50 pM BL 1 was full...

Mitosis and male meiosis were studied in Myrmedobia coleoptrata (Fn.), (Heteroptera, Microphysidae). Spermatogonial metaphase revealed 14 chromosomes (2n=12 + XY). The nucleolar organizing region was found on the X chromosome. No m-chromosomes were present in the complement. Male meiotic prophase was characterized by a prominent condensation stage. At this stage, the sex chromosomes were positi...

Cep55 is a relatively novel member of the centrosomal protein family. Here, we show that Cep55 is expressed in mouse oocytes from the germinal vesicle (GV) to metaphase II (MII) stages. Immuostaining and confocal microscopy as well as time lapse live imaging after injection of mRNA encoding fusion protein of Cep55 and GFP identified that Cep55 was localized to the meiotic spindle, especially to...