Evaluation of vascularization in the walls of preovulatory follicles in mares with endometritis.

Endometritis is a major cause of infertility in mares. The aim of this study is to evaluate the preovulatory follicle (POF) vascularization (A mix, A red, A blue), POF diameter, POF wall thickness, and uterine diameters in mares with or without endometritis. Ten healthy mares and 10 mares with endometritis diagnosed by the combination of transrectal palpation, ultrasonographic examination, and cytology brush were enrolled in the study. Data of the groups obtained at 2 days before the ovulation (day -2) were compared with Student's t-test. Correlations of the parameters were determined by the Pearson correlation test. To the best of our knowledge, this is the first report indicating a lower vascularization of A mix, A red, A blue, and a significantly lower wall thickness in the POFs of the mares with endometritis compared to the healthy ones (p < 0.01, p < 0.05, p = 0.06, and p < 0.001, respectively). Also, a striking and novel inverse correlation between POF wall thickness and uterine diameter (r = -0.785, p < 0.001) and moderate correlations between POF wall thickness and POF vascularizations of A mix and A red (r = 0.436, p = 0.055, and r = 0.427, p = 0.060, respectively) were determined.

Is uterine blood flow influenced by hCG and mare age?

Doppler ultrasonography is a noninvasive technique which enables us to follow the physiologic and physiopathologic changes in blood flow in tissues. It is becoming an essential tool in veterinary medicine, especially in theriogenology. Twenty-seven Arabian mares were grouped by age ('young', 3-10 y, n=15; 'old', 19-23 y, n=12). The uterine arteries of the mares were examined using Doppler ultrasonography when an ovarian follicle ≥35mm was visible (Day -1). After these measurements, human chorionic gonadotropin (hCG; 2500IU) was administered to 14 mares selected randomly. One day later (Day 0) Doppler ultrasonography was repeated and then the dominant follicles were aspirated to collect follicular fluid in all groups. On the next day (Day +1), Doppler indices of the uterine artery blood flow were measured again. Blood samples were also collected just prior to ultrasonography, for measuring serum estradiol and progesterone levels. We found that preovulatory hCG administration had no significant effects on uterine artery blood flow indices, or serum or follicular fluid estradiol concentrations. The uterine artery resistance index might decrease in young mares after ovulation, possibly because of increased uterine perfusion.