Scanning Electron and Light Microscopic Characterization of the Endometrium Exposed to Ozonated Sunflower Oil at High Peroxide Index Value in Postpartum Primiparous Cows.

Abstract The goals of the present study were to characterize the uterine response to the infusion of ozonized sunflower oil in first-calf heifers and to determine the in vitro antimicrobial action of the therapy. A total of 18 cows were submitted to a single treatment with ozonized or non-ozonized oil (O₃ and non-O₃ groups, respectively; n=9 cows/group) between days 10 and 12 after calving. Scanning electron and light microscopy were performed immediately before and 15 days after treatment (D0 and D15, respectively) to assess morphometric and morphological parameters of the endometrium. Additionally, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the treatments were done against uterine bacteria (Escherichia coli, Staphylococcus ssp., Streptococcus ssp. and Arcanobacterium pyogenes) isolated at D10. On D15, the number of endometrial glands was greater (P<0.01) in the O₃ group (32.6±2.5) than in non-O₃ group (11.0±1.0). Endometrial glands from O₃ group had reduced (P<0.01) number of cells (34.1±2.2), diameter (111.9±10.8 µm) and luminal area (2376±830 µm²) after treatment, when compared to the non-O₃ group (57.7±2.9, 2013.5±20.9 µm and 15008±1757 µm², respectively). Scanning electron microscopy indicated the absence of surface structure abnormalities in the endometrium of the O₃ group. Ozonized sunflower oil inactivated (MIC and MBC ≤0.18 µg mL⁻¹) all isolated uterine bacteria. In conclusion, the infusion of ozonized oil at high peroxide index value enhanced the endometrial gland proliferation and the uterine involution through the first weeks after calving in cows. In addition, the ozonized oil had a broad-spectrum germicidal action against uterine bacteria.