The aim of the present research was to verify the influence of two different atmosphere gases (A: 5%CO2, B:
5%CO2, 5%O2 and 90%N2) on three different maturation media on in vitro maturation (IVM) rates for oocytes from
anoestrous and diestrous bitches that were cultured in vitro for 48h. Oocytes harvested from bitches were selected and
allocated into three maturation media groups, cultured in atmosphere A or B. Group 1, oestrous bitch serum; Group 2,
bovine serum albumin (BSA), glutamine, cisteamine; Group 3, BSA, estrogen (E2), epidermal growth factor (EGF).
Progression of nuclear maturation was evaluated under fluorescent microscopy after staining with Hoechst 33342
The results demonstrated that different maturation media was not influenced by the atmosphere in any case. Group 1
showed the lowest maturation rates in both cases: 4.3±1.3 vs 7.3±2.1 and 7.9±2.5 for groups 1, 2 and 3 respectively in
atmosphere A (p≤ 0.5), 0 vs 7.2± 2.9 and 9.3± 4.0 in atmosphere B (p= 0.33). Maturation rates were similar among
treatments 2 and 3 in both atmospheres, were slightly higher for treatment 3. Moreover, group 1 obtained the highest
degeneration rates: 65.5±7.3 vs 39.63±7.1, 28.19±6.4 (p= 0.018) and 71.43±12.2 vs 27.71±10, 25.33± 10.20 (p= 0.010)
for mediums 1, 2, and 3 in atmospheres A and B respectively.
Our findings indicate that atmosphere B seems to be more favorable habitat for canine oocytes and independently of
gassed, maturation with not controlled supplementation, with estrous bitch serum, is not a good option.