Testosterone concentrations in the seminal plasma of cocks ranged from 0.46 to 5.05 ng/ml and were substantially lower than in blood plasma. No significant variation was noted in seminal plasma testosterone concentrations during the light phase of the day, whereas the concentration in blood declined over this period. Spermatozoal concentration and seminal testosterone decreased in the third sample of the semen collected sequentially at 3 h intervals. Testosterone concentrations in seminal plasma (1.57 +/- 0.17 ng/ml) and in the semen from the ductus deferens (1.34 +/- 0.24 ng/ml) were not significantly different.

Summary ― Changes in plasma testosterone (T), thyroxine (T 4 ), triiodothyronine (T 3 ), semen output and remex moult were studied in domestic ganders. A bimodal pattern in both plasma T and sperm concentration was observed during the annual cycle. Ganders started to produce semen at the end of January; maximum semen volume (0.32 ± 0.04 ml) and sperm concentration (148 ± 38 x 10 3 /mm 3 ) were reached in March and a marked decrease was observed after mid-April, when the moult of the remiges began. Plasma T 3 levels peaked in February (9.7 ± 0.6 nmol·I-! ) and this peak coincided with maximum T concentrations (9.8-10.4 nmoi'i!). ). Elevated levels of T 4 were found from late February until mid-April (31.0-33.6 nmol·I-!). Plasma T concentration was low at all stages of remex moult and regrowth. Decreased T 4 levels were found in ganders during remex regrowth from the &dquo;brush&dquo; to half of the full primary growth stage. Higher plasma T 4 levels were found before and after this stage of the moult. A reverse pattern was observed for T 3 concentrations.testosterone / thyroxine / sperm concentration / semen volume / moult / gander Résumé ― Testostérone, thyroxine et triiodothyronine plasmatiques en relation avec la production spermatique et la mue chez le jars domestique. Les changements de concentration plasmatique de testostérone (T), de thyroxine (T 4 ) et de triiodothyronine (T! ainsi que la production de spermatozoïdes et la mue des rémiges ont été étudiés chez le jars domestique. La sécrétion de T et la concentration des éjaculats en spermatozoïdes présente un profil bimodal au cours de l'année. Les premiers spermatozoïdes sont observés à la fin du mois de janvier, leur production est maximale en mars (57 ± 17 x 10 6 /éjaculat) puis diminue en avril au moment où les rémiges commencent à tomber. La concentration de T 3 est maximale (9,7 ± 0,6 nmolll) en même temps que celle de T (9,8 ± 10,4 nmol/1). La concentration en T 4 augmente de la fin février à la mi-avril (31-34 nmoili). Les concentrations plasmatiques de T sont faibles pendant la mue des rémiges; celles de T 4 passent par un minimum aux stades 4-5 de la mue et présentent un profil inverse de celui des concentrations plasmatiques de T 3 .

No abstract

1. The effects of relatively small concentrations of polychlorinated biphenyls (PCB) in the diet of hens on the hepatic microsomal aryl 4-monooxygenase [EC 1.14.14.1] activity in their progeny were investigated. 2. PCB caused enhanced activity of aryl 4-monooxygenase in the progeny.

Auto radiography offers a simple method of giving preliminary information about the metabolism in vivo of steroids. 2. In Japanese quail injected testosterone is metabolised mainly in the gastro-intestinal tract.