Urinary excretion of biologically active chorionic gonadotrophin by the pregnant marmoset (Callithrix jacchus jacchus).

No significant correlation exists between the amount of biologically active marmoset chorionic gonadotrophin (mCG) in urine and results obtained with an immunological pregnancy test. The pregnant marmoset excretes large amounts of oestrogenic steroids, which must be removed, to prevent the enhancement of the response of the bioassay for mCG. More than 99% of these unconjugated and conjugated urinary oestrogens can be removed by extraction with acetone and ether. mCG is excreted throughout pregnancy, maximum levels occurring between the 8th and 9th week of gestation. There is a considerable within- and between-animal variation in the amount of mCG excreted. However, the pattern of gonadotrophin excretion by the pregnant marmoset is similar to that of man and the apes but unlike that of baboons and macaques.