Dissimilarity of Corpora Lutea Within the Same Ovaries or Those from Right and Left Ovaries of Pigs During the Oestrous Cycle

A total of 48 corpora lutea from the right and left ovaries of 2 gilts on Day 9 and 2 gilts on Day 13 of the oestrous cycle were analysed for gonadotrophin binding, progesterone concentration and 3 enzyme activities. The weights of corpora lutea from the right and left ovaries on Days 9 and 13 did not differ, but the values on Day 13 were lower than those on Day 9. The specific binding of 125I-labelled hCG, progesterone concentration, and activities of cytochrome c oxidase (a mitochondrial enzyme), beta-N-acetyl-D-glucosaminidase (a lysosomal enzyme) and glucose 6-phosphate dehydrogenase (a cytosol enzyme) differed, with some exceptions, among the corpora lutea within the same ovaries and those from the right and left ovaries on Days 9 and 13 of the cycle. The gonadotrophin binding differences amongst the corpora lutea appeared to be due to the differences in the total number of available receptors rather than in the receptor affinities. There was no strict correspondence between the magnitude of gonadotrophin binding and luteal progesterone concentration. These data show that porcine corpora lutea within the same ovaries, and those from the right and the left ovary, are quite dissimilar.