In vitro maturation of domestic cat oocytes subjected to different incubation times

Denilsa Pires Fernandes,Roberta Gonçalves Izzo,Alexsandra Fernandes Pereira,Fernanda Araujo Dos Santos,Muriel Magda Lustosa Pimentel,Brenna De Sousa Barbosa,Marcelo Barbosa Bezerra,Luã Barbalho De Macêdo

doi:10.33448/rsd-v10i3.13074

Abstract

The aim of this study was to evaluate the effect of three different incubation times on in vitro maturation of domestic cat oocytes. Thus, ovaries (n = 42) were submitted to slicing procedure and the oocytes recovered were classified; only good quality oocytes (Grade I and II) underwent in vitro maturation for three different periods (24 vs. 30 vs. 36 h) in supplemented TCM-99 medium. After, oocytes were evaluated for cumulus cell expansion and presence of the first polar body. After six replicates (7 ± 1,7 ovaries per replicate), a total of 334 viable oocytes were recovered. Differences (p <0.05) were observed regarding the percentage of oocytes presenting expansion of the cumulus cells, where higher values were observed in the group of oocytes incubated for 36 h (84.3%), when compared to 30 (73.4%) and 24 h (71.0%). Moreover, differences were also observed regarding the presence of the first polar body (24 h: 29.7%; 30 h: 58.2%; 36 h: 69.8%). We conclude that the incubation period influenced the maturation rates, indicating 36 h as the ideal period for the in vitro maturation of domestic cat oocytes in supplemented TCM-199 medium.

Highlights

In vitro maturation (IVM) of oocytes is a primordial and essential step of in vitro embryo production (IVEP), providing the necessary conditions for in vitro fertilization (IVF) and subsequent in vitro embryonic development
It was reported that domestic cat oocyte populations undergo two “waves” of nuclear maturation, the first occurring in 26 h of culture and the second after 28-30 h, mimicking the in vivo copulation and ovulation given in response to induction of sexual stimulus (Johnston et al, 1989; Katska-Ksiazkiewicz et al, 2003; Gómez et al, 2006)
Differences among the three IVM times were observed for both cumulus cell expansion and 1st PB extrusion (P < 0.05)

Summary

Introduction

In vitro maturation (IVM) of oocytes is a primordial and essential step of in vitro embryo production (IVEP), providing the necessary conditions for in vitro fertilization (IVF) and subsequent in vitro embryonic development. Approximately 50-79% of immature oocytes from domestic cats reach nuclear maturation (Snoeck et al, 2016; Sowińska et al, 2016; 2017; Prochowska et al, 2019). The maturation rate can gradually increase over a period of 24 h (Zhong et al, 2015), and the pool of immature oocytes at different development stages may require different maturation periods (Gómez et al, 2006) In this context, it was reported that domestic cat oocyte populations undergo two “waves” of nuclear maturation, the first occurring in 26 h of culture and the second after 28-30 h, mimicking the in vivo copulation and ovulation given in response to induction of sexual stimulus (Johnston et al, 1989; Katska-Ksiazkiewicz et al, 2003; Gómez et al, 2006). A study is needed that seeks consensus on the ideal incubation period to promote oocyte maturation in the feline species

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