MONITORING REPRODUCTIVE DEVELOPMENT, MENSTRUAL CYCLICITY AND PREGNANCY IN THE LOWLAND GORILLA (GORILLA-GORILLA) BY ENZYME-IMMUNOASSAY

Enzyme immunoassay (EIA) of urinary estrone conjugates (EC) and pregna nediol-glucuronide (PdG) was used to monitor ovarian activity during p uberty and to evaluate the use of EIA as compared with radioimmunoassa y (RIA) for assessing normal menstrual cyclicity and pregnancy in lowl and gorillas (Gorilla gorilla). Urinary hormone profiles revealed pube rtal onset of ovarian activity beginning at 5.5 yr in one female, but regular ovarian cyclicity was not established until 7.5 yr. After the onset of puberty, distinct but irregularly spaced urinary EC peaks (21 -38 days) were observed. Luteal phase durations at this time were shor t (5-9 days), and PdG concentrations were low (1.0-1.8 mu g/mg Cr) rel ative to normal adult cycles. During 13 menstrual cycles and four preg nancies in four adults, substantial interanimal variation in absolute concentrations of urinary steroid metabolites was detected, suggesting that ''normal'' population means for this species should be interpret ed with caution. Metabolite excretion profiles for nonpregnant and pre gnant females in the present study were similar to previously reported hormone excretion patterns, and EIA correlated well with RIA for both EC (r = 0.91, P < 0.005) and PdG (r = 0.89, P < 0.005), indicating th at EIA provides a useful alternative to RIA for measuring urinary ster oid metabolites.