291 EFFECT OF DIFFERENT TRANSPORT TEMPERATURES (+4°C, +32°C) ON IN VITRO MATURATION OF OOCYTES COLLECTED FROM CATTLE AND SHEEP OVARIES

Abstract

At present, blastocyst rates in embryos obtained from in vitro maturation of oocytes, and their fertilization and culture, is still not at the desired level. One of the most important problems encountered in in vitro culture studies is seen in the maturation period of oocytes until they reach the fertilizable level. Transport time of the ovaries and, in particular, temperature of the transport medium used are among the factors affecting complete maturation. The aim of this study was to determine the effects of different transport temperatures (4°C, 32°C) of sheep and cattle ovaries on the in vitro maturation of oocytes. Two experimental groups were formed in the study. Sheep and cattle ovaries were put into saline solution at 32°C. The ovaries were transported at the same temperature (Group I) or at 4°C following a 10-min incubation at room temperature (Group II), in 2–4 h to the laboratory (n = 6). For each group, oocytes were collected from ovaries using the dissection method and selected oocytes were matured in their own group in 700 μL TCM-199 (supplemented with pyruvate, LH, FCS) for 23 h at a gas atmosphere of 5% CO₂, 5% O₂, 90% N₂ and at 38.8°C. At the end of maturation, oocytes were cleansed from their cumulus oophorus cells and fixed in acetic acid-ethyl alcohol (1:3) for 48 h. The developmental stages until MII of oocytes stained with aceto-orcein were then examined under the phase contrast microscope. The chi-square test was used for statistical analysis (Table 1). While oocytes obtained from sheep ovaries transported at +32°C reached the MII stage at a faster rate compared to those at +4°C (P < 0.001), no statistically significant difference was observed between the maturation to the MII stage of oocytes obtained from cattle ovaries transported at +4°C and +32°C. As a result of this study, while it was established that cattle ovaries could be transported at both +4°C and +32°C and that there was no difference in oocyte maturation, a medium temperature of +4°C was determined to be unsuitable for transporting sheep ovaries.

Table 1.
Stages of development in sheep and cattle oocytes after 23 h of culture

This work was supported by Istanbul University.