Effect of mammalian luteinizing hormone on the natural sex reversal of the rice-field eel, Monopterus albus (Zuiew)

Abstract

The effect of mammalian luteinizing hormone on sex reversal of the rice-field eel, Monopterus albus (Zuiew) has been investigated by the administration of NIH-LH-S14 into female animals, the sexual status of which was first determined by biopsy of the gonad. Treatment of the female fish with mammalian-LH at a dosage of 3 μg/g-fish/injection, thrice weekly, or 1.5 μg/g-fish/injection daily, for a period of 7.58 wk produced the same effect on the ovary. In all treated fish there was great stimulation of the development of interstitial cells, which showed very intense reactions for 3β-hydroxysteroid dehydrogenase. About 70% of the fish developed testicular lobules showing active spermatogenesis. In some fish, the only sign that showed that the gonad was an ovary at the time of biopsy were a few primary follicles. These results indicate that mammalian-LH is effective in stimulating in Monopterus, firstly, the development of static male germ-cells in the ovary to form testicular lobules with active spermatogenesis and, secondly, the proliferation of interstitial Leydig cells in the gonadal lamellae. Thus the pituitary of Monopterus may play an important role in the onset of natural sex reversal. © 1974.