The conventional ovum pick-up method requires oocytes to be transported from local farms to the laboratory, where they undergo nuclear maturation. However, atmospheric conditions for oocyte transportation differ from those for normal oocyte maturation in vitro. In this study, we examined the effects of conventional and modified oocyte transport conditions on oocyte quality and subsequent embryonic development. Cumulus-oocyte complexes were collected from slaughterhouse-derived bovine ovaries and cultured in few drops of medium on plastic plates in a CO₂-incubator (Control), in plastic tubes containing medium (C-T) in air, or in tubes containing gellan gum and medium (MC-T) in air. C-T conditions reduced mitochondrial functionality (mitochondrial membrane potential and adenosine triphosphate), lipid content, and DNA methylation but increased mitochondrial DNA copy number and phosphorylated AMP-activated protein kinase (P-AMPK) levels compared to those in control oocytes. Furthermore, RNA sequencing analysis of blastocysts derived from these oocytes revealed that C-T conditions affected mitophagy- and AMPK-signaling-related genes. However, MC-T conditions attenuated these C-T-associated changes. In conclusion, conventional C-T conditions affect oocyte metabolism and alter embryo quality, whereas the use of gellan gum as a substrate ameliorates such adverse effects. The oocyte transportation system is inadequate for embryonic production and can induce epigenetic changes. Modifying these conditions with gellan gum is a useful counter-measure.

Tubal abnormalities were evaluated on hysterosalpingo-contrast sonography (HyCoSy) using sodium alginate solution as a contrast agent in 18 repeat breeder cattle. Clear contrast enhancement was observed from the uterine horn to the tubal infundibulum in the patent cases, and the percentage of cases with unilateral or bilateral passage disorder was 64.7%. The post-examination artificial insemination conception rate when ovulatory follicles were present on the patent side was 64.3%, which was significantly higher than 12.5% seen when ovulatory follicles were present on the side affected by passage disorder (P < 0.05). The polymorphonuclear leukocyte percentage in the recovered contrast agent was significantly higher on the passage disorder side than on the patent side, whereas there was no significant difference in C-reactive protein concentrations between the patent and passage disorder sides. The present method can be used for diagnosing tubal abnormalities, and chronic inflammatory changes may be related to tubal passage disorder.