Fertility and corpus luteum characteristics in pigs with plastic devices in the uterine lumen.

on the 1st day of oestrus into one or both uterine horns of cyclic gilts; sham-operated gilts served as controls. Immediate post-operative oestrous cycles averaged 20\m=.\0days for twenty-seven gilts with IUDs and 19\m=.\8days for fourteen controls. Eleven gilts with IUDs were mated at nineteen later oestrous periods; all returned to oestrus after mating, with cycles averaging 21\m=.\2days. Gilts were autopsied at 3, 8 to 10 or 14 days after mating. Ova were fertilized in IUD gilts and most embryos were still alive 8 to 10 days after mating. A high rate of embryonic mortality occurred between 8 and 14 days. Leucocytes were present in the uterine lumen of IUD gilts at 8 to 10 and 14 days after mating. In twenty gilts killed 9 or 14 days after mating, weights of corpora lutea were significantly less in IUD gilts than in controls; luteal progesterone levels, however, did not differ significantly. In the IUD gilts there was no evidence that corpora lutea were smaller on the side of the IUD than on the contralateral side.