Analysis of the morphology of Sus scrofa domesticus oocyte-cumulus complexes exposed to low and ultra-low temperatures

Relevance . The priority task of reproductive technologies in animal husbandry is the development of effective storage protocols for female gametes. One way to preserve gametes is vitrification, which reduces damage to intracellular organelles by increasing viscosity upon cooling and minimizing crystallization. Methods . Various additives to cryoprotectants are used for optimization. In our work, titanium tetrapolyethylene glycolate was used in a 10-fold molar excess of polyethylene glycol (TTP EG *10PEG), the nature of the effect of which on cells was studied during short-term storage at low (5 °С) and ultra-low temperatures (-196 °С). The purpose of the study is a comprehensive analysis of the morphology of gametes and somatic cells (cumulus) of ovarian follicles of pigs after exposure to low and ultra-low temperatures (vitrification) when included in the TTP EG *10PEG low-temperature storage and vitrification protocol. Results . Exposure to TTP EG *10PEG at 5 °С caused an increase in the level of oocytes with subsequent morphological degenerations in points with control (from 13% to 5%, р = 0.005). After vitrification with TTP EG *10PEG: the level of gametes with low cumulus cells expansion increased to 35% in terms of the proportion of control gametes (23%); the proportion of denudated gametes was reduced to 50% compared to the control 65% (р < 0.05); the level of morphologically degenerated gametes corresponded to that of native oocytes (8% each) and was lower than in the control (17%), р < 0.005. The obtained data indicate the protective and cryoprotective effects of TTP EG *10PEG at a concentration of 2%, which suggests the possibility of its use in the technology of intraovarian vitrification of female reproductive cells.