Production of viable bovine embryos by intracytoplasmic sperm injection of oocytes harvested from slaughtered old cows

Mihai Cenariu,Mihai Borzan,Emoke Pall,Remus Chiorean,Sorin Dan

doi:10.52331/cvj.v26i1.8

Abstract

Abstract: (1) Background: Intracytoplasmic sperm injection (ICSI) is currently used to increase fertilization success by avoiding several oocyte or sperm deficiencies that would normally prevent conception after in vivo fertilization or classical in vitro fertilization. This paper aimed at improving the in vitro fertilization protocol of bovine oocytes, harvested from old cows after slaughtering, using intracytoplasmic sperm injection; (2) Methods: Oocytes were harvested by puncture of follicles from ovaries obtained from slaughtered old cows, followed by aspiration. Out of the 127 cumulus-oocyte complexes that were harvested, 84 (66.14%) were declared suitable for cultivation, after morphological evaluation. Following oocyte maturation for 22 hours, 77 cumulus-oocyte complexes were morphologically intact and could undergo the steps required for intracytoplasmic injection of spermatozoa. Frozen-thawed bull semen was used for ICSI and the 77 fertilized oocytes were kept for 24 hours in an atmosphere enriched with 5% CO2.; (3) Results: Fertilized oocytes transformed into 46 zygotes (fertilization rate of 59.74%), while after 168 h of cultivation 38 transferable compact morulae or early blastocysts were obtained; (4) Conclusions: Intracytoplasmic sperm injection can represent a viable alternative to classical IVF, when oocytes or sperm with lower fertility are used.

Highlights

Intracytoplasmic sperm injection (ICSI) is currently used especially in assisted human reproduction as it was shown to be capable of increasing fertilization success by avoiding several oocyte or sperm deficiencies that would normally prevent conception after in vivo fertilization or classical in vitro fertilization (IVF) [1]
They used in vitro-matured (IVM) oocytes that were injected with immobilized bovine spermatozoa, and obtained embryos that developed in vitro up to the blastocyst stage and were further transferred to recipient cows that calved viable offspring
Such inconveniences could be surpassed by ICSI, allowing the prolongation of productive life and number of offspring obtained from valuable cows

Summary

Introduction

The first successful ICSI was reported by Goto et al in 1990 [2] They used in vitro-matured (IVM) oocytes that were injected with immobilized bovine spermatozoa, and obtained embryos that developed in vitro up to the blastocyst stage and were further transferred to recipient cows that calved viable offspring. An interesting study by Magata et al, 2019 [3], proved the beneficial effects of ICSI on the production of chromosomally normal embryos using oocytes harvested from aged cows They showed that aging of females negatively influences the distribution of cortical granules during oocyte maturation, which could lead to abnormal fertilization, low developmental competence of oocytes, or/and increased aneuploidy. Such inconveniences could be surpassed by ICSI, allowing the prolongation of productive life and number of offspring obtained from valuable cows

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