Histological and ultrastructural observation of testis and GtH cell and quantification of sexual steroid hormones in the male Japanese eel during artificially induced maturation

Abstract:

In this paper, histological and electron microscopy observations of the testis and GtH cells were conducted, and ultra-performance liquid chromatography coupled with electronspry ionization-triple quadruple mass spectrometry (UPLC/MS/MS) method was applied to determine the content and changes of 6 steroid hormones in the testis of male farmed mature eels during artificially induced maturation through carp pituitary extract and hCG injection. The results showed that the eel testis developed to fully mature and then absorbed and degraded 10 days post spermiation. The contents of progesterone (P), estradiol-17β (E₂) and estriol (E₃) were below limit of detection. The average contents of testosterone (T), 17α,20β-dihydroxy-4-pregnen-3-one (DHP), and 17α-hydroxypro-gesterone (17α-OHP) were significantly higher than those in the control group. The results indicated that the contents of T, DHP and 17α-OHP were low in the control group, and increased during spermiation and then decreased after spermiation in male eel. The results showed that 17α-OHP, T and DHP might be key elements during testis maturation which are regulated by GtH secretion in the pituitary gland.