Fig. 2

Effects of MTX on the chromosome alignment. Chromosomes were visualized using Hoechst 33342, and were reconstructed using Amira 5.2. Chromosome alignments were observed from the directions parallel and perpendicular to the equatorial plate. The dot line indicates the equatorial plate. a Normal chromosome alignment in the in-vivo matured oocyte is rather regular and looks like a disc-shaped plate, namely, all the chromosomes are neatly arranged at the equatorial plate. We used a short circular cylinder as the model of chromosome plate, and the volume and surface area of this cylinder were same to the chromosome pate. The cylinder height (H) and univalent length (L) were measured. The normal alignment had the characteristic of H ≤ 2 L. b The irregular alignment had the characteristic of H>2 L. c The misaligned alignment was that individual univalents were not on the equatorial plate, while others were still along the plate. The red arrow indicates the misaligned chromosome. d The chromosome alignment of all the chromosomes clustered together in a great mass was defined as cluster alignment, and the equatorial plate can’t be found. The rates of abnormal chromosome alignment and chromosome volumes were shown in e. Chromosome volume was estimated by the spatial area occupied by fluorescence, and was calculated using Amira 5.2. The oocyte numbers for analyzing the rates of abnormal chromosome alignment were 384 in the control group, and 275 oocytes in the MTX group. ** p<0.01