Urinary steroid and gonadotropin excretion across the reproductive cycle in female Wied's black tufted-ear marmosets (Callithrix kuhli)

Details of the endocrinology of reproduction in the genus Callithrix are known only for the common marmoset, C. jacchus. This paper presents the patterns of urinary pregnandiol-3-glucuronide (PdG), urinary estrone conjugates (E ₁C), and gonadotropin excretion throughout the reproductive cycle of Wied's black tufted-ear marmoset (C. kuhli) as determined via steroid conjugate enzyme immunoassays (EIA) and gonadotropin radioimmunoassays (RIA). Postpartum ovulation occurred at 13.6 ± 1.2 days after parturition (n = 12) and was characterized by low PdG and E ₁C concentrations accompanied by a spike in luteinizing hormone (LH)/chorionic gonadotropin (CG) concentration. After conception, PdG concentrations increased dramatically until they dropped to periovulatory concentrations in the third trimester of pregnancy. Mean PdG concentrations in the first and second trimesters (33.7 ± 8.4 and 39.0 ± 10.9 μg/mg creatinine, respectively) were three times that of third trimester concentrations (11.7 ± 1.4 μg/mg Cr; n = 8). Urinary concentrations of E ₁C rose more gradually during pregnancy and remained higher prepartum than urinary concentrations of PdG. Urinary gonadotropin concentrations also increased after conception (first trimester concentrations = 24.5 ± 4.5 ng/mg Cr) and continued to increase in the second trimester (51.4 ± 7.6 ng/mg Cr), until they finally decreased in the third trimester (mean = 7.9 ± 1.4 ng/mg Cr; n = 8). The interbirth interval was 156.3 ± 2.9 days (n = 6), with a gestation of 143.1 ± 1.6 days (n = 8). Nonconceptive cycle length was 24.9 ± 0.6 days (n = 4). The results of this study suggest strong similarities in reproductive parameters in the genus Callithrix.