Oogenesis and steroid profiles during the reproductive cycle of female angelfish Pterophyllum scalare (Cichlidae)

Abstract

The changes in oogenesis and sex hormones during the reproductive cycle of the multi-spawning, synchronic angelfish, Pterophyllum scalare, were studied. The average cycle lasts 11 days, during which the oocytes pass through vitellogenesis to maturation before spawning occurs. Six major stages of the oocytes during oogenesis are described. The patterns of steroid changes were traced by high pressure liquid chromatography and by radioimmunoassay. The levels of the main steroids 17P-estradiol (E^) and testosterone (T), rose during vitellogenesis while 17a, 20P, dihydroxy-4-pregnen-3-one was very low and did not change markedly. The levels of E^ and T increased significantly in the plasma by an injection of carp pituitary extract which also led to a higher percentage of oocytes in maturation than was found in the control group.