Histological Characteristics of the Endometrium and its Affecting Factors in Dairy Cattle (Bos taurus) on Embryo Transfer Day

In cows embryo transfer occurs on the 7^th day of the oestrous cycle. Embryo survival and successful pregnancy depend on many factors, including early interaction between embryo and endometrium. Therefore, the aim of our research was to describe histo-morphological characteristics of endometrium in donor and recipient cows on obtaining and transfer day, respectively (7^th day of the oestrus cycle). In addition, progesterone and oestradiol levels, the ipsilateral and contralateral corpus luteum, animal age, lactation number and days postpartum were determined. The results of the study revealed a significant difference in endometrial gland cell size, vacuolisation of glandular epithelium cytoplasm, and stromal oedema in the donor and recipient cows. However, these parameters were related only to the level of progesterone in the blood, and no other investigated factors in this study.