Long term storage of ovaries can provide opportunity to rescue oocytes from ovaries of endangered or
recently dead felids. The objective of the study was to examine the effect of two ovary transport
temperature (4 vs 37oC) and time on cumulus cell apoptosis and maturation rates of cat oocytes in vitro.
Ovaries were collected from 15 domestic cats at various stages of oestrous cycle by routine
ovariohysterectomy following anaesthesia at different local veterinary clinics, and maintained in PBS
(phosphate buffer saline) at 37 and 4oC. In order to determine the effects of storing time, some of the
ovaries were transported at 4oC stored at the same temperature for 24 h. Selected COCs were maturated at
38 oC for 48 h in four-well petri dishes included 500μL modified synthetic oviduct fluid (mSOF) medium
under mineral oil in a humidified 5% CO2 incubator. The morphological features of apoptosis were
analysed in the cumulus cells at the beginning of in vitro maturation (IVM) in both transporting
temperature groups (4 and 37oC) and after 24 h of cold stored group. The apoptosis rates were determined
with TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) using ApopTag®
Plus Peroxidase In Situ Apoptosis Kit (Millipore, S7101; Darmstadt, Germany). In all groups, IVM rates
of oocytes were determined after maturation period using Hoechst (33342) staining. Although the
apoptotic morphological features were seen rarely and similar rates in 37 and 4oC transporting groups
(19.40 and 21.55 %) but, it was seen more intensely in the 24 h cold stored group (34.80 %). The
differences between two transport and cold stored groups rates were statistically significant (p<0.001).
The IVM findings were 49.77, 44.55 and 18.90 % at 37oC, 4oC transporting and 24 h cold stored groups
In conclusion, the results of this study suggest that (I) cumulus cells of cat oocytes are partially exposed
to apoptosis during transportation at both warm and cold temperatures, (II) the cumulus cells exposed at
much higher rates after cold storing 24 h and (III) the cold storing of cat ovaries at 24 h, have deleterious
effects on in IVM rate of oocytes.