Influence of Human Chorionic Gonadotropin on Maturation in Striped Murrel, Channa striatus

Abstract

Gonadal development, gonadosomatic index (GSI), oocyte diameter, fecundity, histology and level of serum steroid hormones (testosterone and estradiol-17β) were observed in captive striped murrel (Channa striatus Bloch) implanted with human chorionic gonadotropin (HCG) capsules and cholesterol capsules as control for a period of five months after implantation. HCG implants induced a significant increase in the GSI of male and female fish. The GSI values were highest in the fourth month (December) and lowest in the first month (September) in HCG implanted fishes. Variation in ova diameter of control and HCG implanted fishes revealed the presence of large size ova in HCG implanted fishes throughout the study period. Similarly, a significant increase in the fecundity of HCG implanted fishes was also observed. Fecundity was highest in December (15415 eggs) in HCG implanted fish, whereas only 2245 eggs were observed from control fish in the above sampling period. In control fish, only perinucleolar and primary oocytes were observed throughout the study period. Similarly, in testis, spermatogonia and few spermatocytes were observed till the end of the study period. Histological examination of the gonads of HCG implanted fish showed that numerous oogonia were present in the ovary after one month of HCG implantation which continued to develop into vitellogenic oocytes in the third and fourth months. The ovary in the fifth month of sampling of HCG implanted fish consisted of oocytes having completed the process of vitellogenesis. The testicular histology of HCG implanted fish showed primary spermatocytes in the first month and testis contained a large reserve of primary spermatocytes and spermatids in the second and third months. A large number of spermatids were observed in the testis in the fourth month of sampling and the testis in the fifth month of sampling predominantly contained spermatozoa. Serum testosterone level was highest (18ng•ml-1) during the fourth month (December) in HCG implanted male fish and serum estradiol-17β level was highest (61.5pg•ml-1) in the third month in HCG implanted female fish. The results of the present work can be used as a reference study for controlled breeding and reproduction of striped murrel, C. striatus.