ADVANCED OVULATION IN GILTS BY THE INTRAUTERINE APPLICATION OF A LOW-MOLECULAR-MASS PRONASE-SENSITIVE FRACTION OF BOAR SEMINAL PLASMA

The shortening of the time interval between the onset of oestrus and o vulation in sows by the transcervical administration of seminal plasma was investigated in 23 German Landrace gilts, using the technique of single horn infusions (Mariensee model) in combination with the transc utaneous sonographic monitoring of ovaries. Preparative surgery compri sed the detachment of the left uterine horn from the corpus, leaving t he caudal end open to the peritoneal cavity but sealing the corpus wou nd. The left ovary was loosely tied to the ventral abdominal wall for better sonographic distinction. The animals were used in two to four c onsecutive cycles. After detection of oestrus by the teaser boar, the patent (right) horns were filled by transcervical infusion of 100 ml o f a variety of test solutions. Ovulation was probed by transcutaneous sonography at intervals of 4h thereafter. Native seminal plasma provok ed ovulation in the ipsilateral ovary of the treated horn 10.7 h earli er than in the contralateral ovary. This effect was reduced to 7.3 h a fter charcoal treatment of seminal plasma; addition of 10 mu g oestrad iol restored the effect in full, while 10 mu g of oestradiol in PBS sh ortened the time interval to only 3.3 h versus the control ovary. Litt le effect was seen with oestrone sulfate, none with prostaglandins in PBS or with PBS alone. The preliminary characterization of the nonster oidal component of seminal plasma advancing ipsilateral ovulation afte r transcervical infusion suggests a proteinaceous nature. The activity resides in the 1-10 kDa fraction separated by ultrafiltration and is lost after treatment with pronase.