Effect of endometrial damage and prostaglandin F2α on experimental cystic ovarian follicles in the cow

Abstract

Injection of increasing doses of testosterone during the follicular phase of the oestrous cycle resulted in the cystic ovarian condition in experimental cows. Peak concentrations of oestradiol in daily plasma samples varied between 25 and 35 pg/ml, although values as low as 6 pg/ml were noted. Progesterone values were generally less than 2 ng/ml. The appearance of the endometrium was characteristic of cows with high oestradiol concentrations. By scanning electron microscopy (SEM) the luminal surface was uneven and oedeniatous with numerous cilia and microvilli present. Both SEM and light microscopy (LM) revealed dilated uterine gland openings filled with secretory products. As previously reported, the induced cyst underwent spontaneous atresia between days 13 and 17 in the presence of a healthy uterus. In four instances, damage to the endometrium by intrauterine injection of Lugol’s iodine solution or of a culture of Escherichia coli organisms resulted in persistence of the cystic follicle. By SEM, exfoliated epithelial cells, inflammatory cells and fibrin with areas of necrosis were seen. Necrosis was also observed by LM and uterine glands were distorted and contained inflammatory exudate. After cessation of iodine injection or following antibiotic treatment, endometrial repair occurred shown by regenerating epithelial cells with cilia and microvilli. During this repair the persistent cysts underwent atresia, accompanied by a marked decline in oestradiol values. Cystic atresia was observed in six instances after intrauterine injection on two successive days with 6 mg of prostaglandin F2α (PGF2α during endometrial damage with iodine solution. In the first two instances, cyclic ovarian activity did not resume during the 30 day post-treatment period. An intramuscular injection of progesterone was therefore given at the time of PGF2α treatment in an attempt to facilitate a return in ovarian activity. When 1 g of depot progesterone was injected, values of 2 ng/ml in plasma for up to 10 days were achieved but with no return in ovarian activity after cystic atresia. In contrast, injection of 1 g of progesterone in oil resulted in a brief peak of 5 to 6 ng/ml in plasma progesterone values and new follicular growth with ovulation occurred within 10 days of cystic atresia. Similarly, when progesterone in oil was administered with PGF2α to three cows with spontaneously occurring cystic follicles, cystic atresia was followed by new follicular growth and ovulation.