Detection of Macaque Chorionic Gonadotropin in the Placenta of the Cynomolgus Monkey (Macaca Fascicularis)

An appraisal of the mouse uterine weight assay for the bioassay of chorionic gonadotrophin in the macaque term placenta

“…It is advisable therefore to determine by experiment the suitability of a particular strain for the assay of hCG. The inability of Fujiwara et al (1980) to detect CG in placentae of cynomolgus monkeys after the 5th week of gestation could be due to the insensitivity of the assay mice and/or the injection technique used. Doubling the dose of hCG produced a small increase in mouse uterine weight in their assay and the slope value (b) of the regression line was 0-299 and significantly different (P < 0-001) from 1.…”

“…Burn, Finney & Goodwin (1950) pointed out that when using bioassay methods it was "unwise to be satisfied with results unless the curve relating effect to dose shows a reasonably steep rise". The method of Fujiwara et al (1980) of injecting animals over a period of 48 h and performing the autopsy 96 h after the first injection could have contributed towards a lower response. It has been shown that the response of the ovary and uterus of the immature mouse to injected gonadotrophin decreased by 75 and 67% respectively when the animals were killed at 96 h instead of 72 h after the first injection (Levin & Tyndale, 1937).…”

“…1). Because of this it was not possible to make a dose-for-dose comparison between our bioassay and that used by Fujiwara et al (1980), in which 1, 2 and 4 i.u. hCG were injected per mouse.…”

“…The increase in mouse uterine weight to lower doses of hCG was examined using the dose schedule of Fujiwara et al (1980) and by varying the time at which mice were killed. For comparison the assay method used routinely was done in parallel.…”

“…These differences are of interest, especially as both groups used a mouse uterine weight assay (Levin & Tyndale, 1937) of apparently similar sensitivity. Fujiwara, Suzaki, Yamada & Honjo (1980) used a similar assay to estimate the concentration of CG in placentae of cynomolgus monkeys (M. fascicularis). Only placentae obtained in the 4th and 5th week of gestation could be shown to contain gonadotrophin, which would seem to support the notion that the production of CG by macaques is limited to the first 10 weeks of pregnancy.…”