Radioimmunoassays are used to follow plasma 1 I-oxotestosterone and glycoprotein gonadotropin levels related to sperm production in male rainbow trout at the onset of spermiation. The 11-oxotestosterone concentrations are higher in the plasma of males giving a measurable volume of sperm. When these levels increase as spenniation progresses, the gonadotropin level tends to decrease slightly. Furthermore, the quantities of collected sperm are positively correlated with the 11-oxotestosterone levels, but not with GTH secretion.
Summary. Plasma immunoreactive t-GTH and androgens, sperm production and biochemical changes in seminal fluid were studied during the spermiation period in rainbow trout. The volume of sperm collected by hand-stripping was very low (< 0.1 ml) at the onset of spermiation, increased slowly during the next 4 weeks and sharply thereafter. Plasma t-GTH was high (6 ng/mi) at the onset and then decreased ; the sharp rise in sperm production started when circulating androgens had reached maximum values. In a second phase (b-12 weeks), the elevation in sperm production was strongly correlated wth plasma t-GTH, while plasma androgens fluctuated. Spermatocrit did not vary significantly during the period studied so that increased sperm production corresponded to an elevation in spermatozoal production. During spermiation Na + ionic concentration in the seminal fluid increased sharply and that of K + only slightly. Total protein in the seminal fluid decreased significantly after 8 weeks.Introduction.
Summary. Plasma gonadotropin (GTH) and 17p-estradiol (17p-E 2 ) levels and oocyte stage have been studied in the common carp, Cypinus carpio L., after classical « hypophysation » (two intraperitoneal pituitary injections of 0.3 mg/kg and 2.7 mg/kg at a 12-hr interval) or LH-RH treatment (two intracardiac injections of 3 fL9/ kg at a 3-hr interval). After the first pituitary injection of LH-RH treatment, GTH increase was followed by a significant increase of 17p-E 2 7 hrs after the injection. The higher GTH levels after the second pituitary injection did not increase that secretion. After classical « hypophysation », one-half of the females ovulated. There was no difference between spawning and non-spawning fishes in relation to hormonal parameters. LH-RH treatment only induced a shifting of the nucleus.Introduction.
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