Annual cycle of plasma oestradiol-17β in the female trout Salmo gairdneri

Abstract

Summary. Levels of oestradiol in plasma of adult female rainbow trout Salmogairdneri were determined during the annual reproductive cycle using a radioimmunoassay. From January to June, during previtellogenesis and the period of endogenous vitellogenesis plasma levels were low (1,3 ! 0,2 ng/mi). At the beginning of the period of exogenous vitellogenesis, the cestradiol level rose and a maximum (16,9 ! 0,2 ng/ml) was reached at the end of vitellogenesis in November, some weeks before spawning. A positive correlation (r = 0,58) was established between plasma oestradiol levels and the gonadosomatic index. From enzymatic cytochemical studies it was concluded that the granulosa cells, as well as the interstitial cells in the ovary, are involved in oestradiol production.Introduction.

Annual reproductive cycle of the captive female Japanese sardineSardinops melanostictus: Relationship to ovarian development and serum levels of gonadal steroid hormones

“…Generally, a high plasma level of estradiol-17/3 is associated with vitellogenesis, whereas in many other species a low concentration occurs prior to oocyte maturation or spawning, e.g. salmonids (Crim and Idler 1978, Lambert et al 1978, Scott et al 1980, Kagawa et al 1981, Ueda et al 1984, Dye etal. 1986, Fitzpatrich etal.…”

“…Correlations between seasonal changes in plasma levels of gonadal steroids and gonad condition have been well documented in a number of freshwater species, including Salmoniformes (Crim and Idler 1978, Lambert et al 1978, Scott et al 1980, Kagawa et al 1981, Whitehead et al 1983, Ueda et al 1984, Hirose et al 1985, Dye et al 1986, Fitzpatrick et al 1986, Truscott et al 1986); cyprinids (Kagawa etal. 1983b, Stacey etal.…”

Role of maternally derived immunity in fish

“…The correlation between the fish gonad development and plasma level of gonadal steroids with seasonal changes is a well known fact [184,185]. Similarly, the immunocompetence, is often affected by seasonal changes.…”

Serum thyroxine, estradiol-17β, and testosterone profiles during the parr-smolt transformation of masu salmon, Oncorhynchus masou

“…During the period of smoltification, the gonad was immature; only spermatogonia were observed in the testis, and the most developed oocytes in the ovary were at the peri-nucleolus stage. According to Lambert et al (1978), and Lambert and van Bohemen (1979), the ovary in the previtellogenic rainbow trout showed low activity of estrogen synthesis, while the activity of E 2 synthesis in the brain might be responsible for the high circulating E 2 levels. Yamada et al (1989a) investigated the changes in the E 2 production (conversion of T to E 2 ) in the ovary and brain of the masu salmon accompanying smoltification.…”