Urinary chorionic gonadotropin in middle and late pregnancy in the chimpanzee.

Abstract

Twenty-four hr urine samples were collected at 7-day intervals from two pregnant chimpanzees during middle, late and post-partum phases of gestation. An aliquot of each sample was prepared by acetone precipitation and the remainder was extracted by a kaolin-acetone method. Chimpanzee chorionic gonadotropin (ChCG) activity was determined by radioimmunoassay (RIA) and rat uterine weight (RUW) bioassay methods. Second International Standard Human Chorionic Gonadotropin (HCG) was a suitable reference preparation for both assay methods. Samples prepared by acetone precipitation showed more ChCG activity in RIA and RUW bioassay than those extracted by kaolinacetone procedures, but in general, patterns of change were similar in samples prepared by both methods. ChCG levels were elevated during midgestation. Beginning about 40–50 days before either abortion or normal delivery, the ChCG levels fell precipitously until about 25 days prior to expulsion of the placenta. A brief rise in ChCG excretion was evident at t...