Morphological Study of Gonads of Rainbow Trout (Oncorhynchus Mykiss) afterAdministration of 17-Alpha- Methyl Testosterone Via Feed and/or Immersion

Objective: To study the morphology ofgonads and sperm ducts of sex reversed male rainbow trout after administration of I 7-cr- methyl testosterone. Animals: Rainbow trout, Oncorhynchus mykiss. Procedure: l7-alpha-methyl testosterone (17-alpha-MT) was administered to rainbow trout in 5 treafinents as follows: I) rwo times immersion of eyed eggs and yolk sac alevins in 250 pg/l bath with 2 hours duration and 8 days interval. II) three times immersion of eyed eggs and yolk-sac alevins in 250 trrgil bath with 2 hours duration and 4 days intervals .III) two times immersion of eyed eggs and yolk sac alevins in 250 pg/l bath with2hours duration and 8 days intervalplus oral adminishation of 3ppm l7-cr-MT starting from active feeding of larvae for 90 days. IV) oral administration of 3ppm l7-alpha-MT starting from active feeding of larvae for 70 days. V) oral administration of 30ppm 17-a-MT starting from active feeding of larvae for 120 days. In addition, a control group was maintained with no hormonal treatment. 20 fishes from each treatment as well as control groups were examined morphologically for their reproductive organs at the age of 24 months. Results: Arange of normal to totally atrophic reproductive organs was observed in different treatment groups. Four types of sperm ducts were detected ranging from normal open-ended sperm ducts containing fluid semen, closeended sperm duct containing fluid semen, close-ended sperm duct lacking fluid semen, to close-ended atrophic sperm duct with no semen. The highest number of functional males with the ability of production of fluid spenn was found in treatment II. Conclusion: 17-alpha-MT administration in an optimal dosage and route to female rainbow trout can produce functional males with the ability of normal sperm production although the gonads and sperm ducts may be affected morphologically.