Morphometric categorization of the human oocyte and early conceptus.

Morphometrical procedures were used to quantitatively evaluate human oocytes and embryos in an IVF programme. The metaphase II oocyte was an irregular 3.5 x 10(6) microns 3 sphere of 1.05 coefficient of form. The ooplasmic volume of 1.4 x 10(6) microns 3 was reduced by 10% by fertilization. The zona pellucida behaved as a stable and almost spherical envelope of 1.8 x 10(6) microns 3 volume and 17 microns thickness. Through the first three cleavages, mean blastomere reduces 28.5% volume per division, evolving from an irregular spherical shape with 0.9 coefficient of form to an ellipsoid (0.8) at the 8-cell stage. The coefficient of diversity between sister blastomeres progressively moved from 1.4 to 1.6 during the first two (2n) cleavages. The coefficient of diversity also increased at 3-cell (2.2) and 6-cell (2.6) asynchronous divisions. Morphologically abnormal embryos showed some morphometrical differences. Embryos which successfully implanted and progressed to birth showed a higher coefficient of diversity between sister blastomeres.