The Using of Morphometric Parameters in Establishing the Viability of Mouse Embryos

Abstract

The aim of this paper was to investigate if morphometric parameters can be used in establishing the viability of the mouse embryos. For the experiments, we used mouse mature oocytes and embryos in vivo obtained. The morphometric parameters taken into consideration were: pellucid zone thickness, outer and inner diameter, and outer and inner perimeter and for oocytes and zygotes the cellular mass diameter was also measured. The oocytes were measured immediately after recovery then they were in vitro fertilized. After 4-6 hours after fecundation the oocytes that manifested the extrusion of the second polar body (zygotes) were measured, and at 24 hours after fecundation the unfertilized oocytes were also measured. The embryos were obtained from mouse females superovulated with gonadotrope hormones (eCG and hCG). For the experiments we used embryos in different developmental stages (2, 4 and 8 cells, morula and blastocyst). After recovery the embryos were morphologically analyzed and divided in viable (quality code 1, 2 and 3) and nonviable embryos (quality code 4) (IETS Manual, 1989) and they were measured for establishing the morphometric parameters value. The data obtained were statistically analyzed using Minitab 15, and T test. For the oocytes it was noticed that the pellucid zone thickness is registering a slightly increase if the oocyte is fertilized, without significantly difference from recovery, but if the oocyte is not fertilized the pellucid zone thickness decrease from 8.3±1.5 µm to 8.0±1.5 µm. For the embryos in early developmental stages only the thickness of the pellucid zone can be an indication of the viability. For the embryos in morula stage the thickness of the pellucid zone and inner diameter can be used as indicator of viability. For the embryos in blastocyst stage the thickness of the pellucid zone, the inner and outer diameter can be used as a viability indicator.