Effect of Intracytoplasmic Sperm Injection (ICSI) on Mouse Embryos Preimplantational Development

It is known that the in vitro culture (IVC) of preimplantation embryos is associated with changes in gene expression. It is however, not known if the method of fertilization affects the global pattern of gene expression. We compared the development of mouse blastocysts produced by intracytoplasmic sperm injection (ICSI) versus blastocysts fertilized in vivo and cultured in vitro from the zygote stage (IVC). At the end of cultivation (96 hrs for blastocyst stage embryos), expanded blastocysts of each group were randomly selected, and ICM and total cells number were differentially stained. The total cell number of blastocysts was estimated by counting the total number of nuclei using DAPI staining. Cell number for inner cell mass (ICM) was estimated by counting the OCT4 (POU5FL) positive cells. Digitally recombined, composite images were analyzed using the Zeiss Axion Vision software and Zeiss Apotome. All 5–10 optical sections were divided using a standard grid over each layer to count all. Comparing the total cells and the ICM cells number, it appears that each method of fertilization has a unique pattern development. The developmental rate and the total cell number of the blastocyst were significantly lower in ICSI versus in vivo fertilized embryos which affect the embryonic developmental rate and the total cell number of blastocysts.