Conjugates of ovarian steroids, including 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (maturation-inducing steroid), accumulate in the urine of a marine teleost (plaice; Pleuronectes platessa)

J Endocrinol. 1989 Oct;123(1):R1-4. doi: 10.1677/joe.0.123r001.


Free and conjugated 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P), 17 alpha,21-dihydroxy-4-pregnene-3,20-dione (11-deoxycortisol) and 3 alpha,17 alpha,21-trihydroxy-5 beta-pregnan-20-one (3 alpha,17,21-P-5 beta) were measured by radioimmunoassay in matching blood plasma and urine samples from plaice (Pleuronectes platessa) females at several ovarian maturity stages: post-vitellogenesis (IV), final oocyte maturation (V), and ovulation (VI). Free steroids were generally low in all samples. Conjugated steroids were up to 2 orders of magnitude higher in urine than in plasma samples. Conjugated 17,20 beta-P was higher in stage V than in stage IV or VI females. Conjugated 11-deoxycortisol was higher in stage IV and V females. Conjugated 3 alpha,17,21-P-5 beta was higher in stage V and VI females. These results support earlier studies which indicated that 17,20 beta-P was the most likely maturation-inducing steroid (MIS) in plaice, and that the urine might be a vehicle for steroid pheromones synthesized by the gonads.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cortodoxone / analogs & derivatives
  • Cortodoxone / urine
  • Female
  • Flatfishes / metabolism*
  • Hydroxyprogesterones / urine*
  • Oogenesis
  • Ovulation
  • Radioimmunoassay
  • Time Factors


  • Hydroxyprogesterones
  • 17 alpha,20 beta-dihydroxypregn-4-en-3-one
  • tetrahydro-11-deoxycortisol
  • Cortodoxone