Effect of HCG antiserum on ovulation and corpus luteum formation in the monkey (Macaca fascicularis)

Abstract

Considerable evidence is available from recent literature (1,2,3) that ovulation can be induced in the Simian primates by exogenous administration of LH or HCG. It has also been shown, using radioimmunoassay, that a surge of LH is released into the plasma of the intact cycling monkey just prior to ovulation (4,5). An attempt has been made here to neutralize this endogenous LH surge by giving HCG A/S and thereby study the role of LH in inducing ovulation and formation of a functional corpus luteum in the monkey. Antiserum (A/S) to HCG (Ayerst) was raised essentially according to methods described earlier (6) by administering to three New Zealand rabbits repeated injections of HCG in Freund's complete adjuvant (Difco) over a period of several months. The antiserum was absorbed with 1:10 diluted normal human serum and a Kaolin-acetone extract prepared from the urine of nursery school children. The cross-reactivity of this antiserum with human pituitary LH (HLH) and monkey pituitary LH (MPE, an extract of lyophilized pooled monkey pituitaries), was established both by the Ouchterlony double diffusion test and the ovulation inhibition test. The latter test consisted in administering to 22-day-old Charles River female rats 12 1U of PMS followed 48 hours later by an i.p. injection of 2.5 μg of HLH or 1-2 mg of MPE. Antiserum in graded doses was administered by i.p. route 1-2 hours prior to the LH injection. The number of ova shed were counted the next morning according to the method of Ying and Meyer (7). One ml of HCG A/S could neutralize in this test the response of up to 50 μg of HLH or 3 mg of MPE.