Histological effects of the synthetic androgen, 17 a-methyl testosterone, on the gonadal sex differentiation of nile tilapia (Oreocromis niloticus, Linnaeus) /
Paller, Vachel Gay
Histological effects of the synthetic androgen, 17 a-methyl testosterone, on the gonadal sex differentiation of nile tilapia (Oreocromis niloticus, Linnaeus) / by Vachel Gay Paller. - Los Baños, Laguna : University of the Philippines, 1997. - xiii, 55 pages : illustrations ; 28 cm.
Thesis (Master of Science in Zoology) University of the Philippines.
Includes bibliographical references.
VELASCO-PALLER, VACHEL GAY B., University of the Philippines Los Banos, October 1997, Histological Effects of the Synthetic Androgen, 17a-Methyltestosterone, on the Gonadal Sex Differentiation of Nile Tilapia (Oreochromis niloticus, Linnaeus). Major Professor: Dr. Rafael D. Guerrero III
A synthetic androgen, 17a- methyltestosterone at a dose of 0, 15, 30, and 60 mg/kg diet were administered to fry of Nile tilapia (Oreochromis niloticus L.) daily for a period of 25 days from 7 days post hatching. Sampling was done every week during treatment and at 60 days post-hatching. The control and treated fry were processed and examined both for light and electron microscopy to determine the effects of 17a-methyltestosterone (MT) on the gonadal sex differentiation of O. niloticus.
Gonadal development was normal from 7 until 14 days Posthatching or when the fry measured 7-14 mm in total body length. Histological changes began to appear at 21-30 days posthatching or at a total body length of 15-25 mm, except for those treated with 15mg MT/kg diet. Intersexes were observed in some gonads treated with a 30mg MT/kg diet. In fry treated with 60mg MT/kg diet gonadal masculinization was observed with the oocytes developing late and degenerating afterwards.
Electron microscopic observations showed that germ cells from the treated gonads of presumptive females had very few endoplasmic reticula and mitochondria with undefined cristae. On the other hand, gonads of presumptive males developed into structurally defined testes like those of the control.
The results indicate that 17a - methyltestosterone at a dose of 60mg/kg diet administered to fry for 25 days from 7 days post hatching, under aquarium conditions, is effective in inducing gonadal masculinization in O. niloticus.
Tilapia
Nile tilapia
597 / P17 1997
Histological effects of the synthetic androgen, 17 a-methyl testosterone, on the gonadal sex differentiation of nile tilapia (Oreocromis niloticus, Linnaeus) / by Vachel Gay Paller. - Los Baños, Laguna : University of the Philippines, 1997. - xiii, 55 pages : illustrations ; 28 cm.
Thesis (Master of Science in Zoology) University of the Philippines.
Includes bibliographical references.
VELASCO-PALLER, VACHEL GAY B., University of the Philippines Los Banos, October 1997, Histological Effects of the Synthetic Androgen, 17a-Methyltestosterone, on the Gonadal Sex Differentiation of Nile Tilapia (Oreochromis niloticus, Linnaeus). Major Professor: Dr. Rafael D. Guerrero III
A synthetic androgen, 17a- methyltestosterone at a dose of 0, 15, 30, and 60 mg/kg diet were administered to fry of Nile tilapia (Oreochromis niloticus L.) daily for a period of 25 days from 7 days post hatching. Sampling was done every week during treatment and at 60 days post-hatching. The control and treated fry were processed and examined both for light and electron microscopy to determine the effects of 17a-methyltestosterone (MT) on the gonadal sex differentiation of O. niloticus.
Gonadal development was normal from 7 until 14 days Posthatching or when the fry measured 7-14 mm in total body length. Histological changes began to appear at 21-30 days posthatching or at a total body length of 15-25 mm, except for those treated with 15mg MT/kg diet. Intersexes were observed in some gonads treated with a 30mg MT/kg diet. In fry treated with 60mg MT/kg diet gonadal masculinization was observed with the oocytes developing late and degenerating afterwards.
Electron microscopic observations showed that germ cells from the treated gonads of presumptive females had very few endoplasmic reticula and mitochondria with undefined cristae. On the other hand, gonads of presumptive males developed into structurally defined testes like those of the control.
The results indicate that 17a - methyltestosterone at a dose of 60mg/kg diet administered to fry for 25 days from 7 days post hatching, under aquarium conditions, is effective in inducing gonadal masculinization in O. niloticus.
Tilapia
Nile tilapia
597 / P17 1997