Radioimmunoassay of Progesterone in Peripheral Plasma of the Domestic Fowl in Various Physiological States and in Follicular Venous Plasma

Abstract

A radioimmunoassay for the estimation of progesterone in plasma from the domestic fowl is described. Antibodies were raised in goats to progesterone conjugated at the 11 position of the steroid nucleus to bovine serum albumin. An antiserum of high specificity was obtained which allowed the estimation of progesterone in extracts of plasma without purification. The sensitivity of the assay, which was 25 pg using an antiserum dilution of 1:8000, allows the determination of progesterone in 200 μl plasma. The accuracy and precision of the method were highly satisfactory. Plasma progesterone levels in laying hens ranged from 0.67–9.60 ng ml−1 with a mean value of 3.13 ± 0.37 ng ml−1 but were low (< 0.10–0.67 ng ml−1) in plasma from moulting, ovariectomised and hypophysectomised hens and in plasma of intact and castrated cockerels. Progesterone concentrations in blood obtained from a follicular vein ranged from 12.8–133.1 ng ml−1; these values were 8–50 times higher than in peripheral blood collected concurrently. The results suggest that high concentrations of progesterone found in the blood of laying hens are associated with the ovulatory cycle and that the preovulatory follicle secretes significant amounts of progesterone.

A Preliminary Assessment of the Source of Oestrogen Within the Ovary of the Domestic Fowl, Gallus Domesticus

“…All these results indicate that, unlike progesterone (Furr, 1969(Furr, , 1973 (Senior & Cunning¬ ham, 1974). Certainly, the major follicles contain enzymes necessary for oestrogen biosynthesis (Chieffi & Botte, 1965;Boucek & Savard, 1970) and further investigations are essential to determine whether a large increase in oestradiol output by the follicles occurs 4 to 8 hr before ovulation.…”

“…Collection offollicular venous blood A polyvinyl cannula was inserted (Furr, 1973) (Hertelendy & Common, 1965).…”

“…The follicular vein cannulation procedure will have some influence on blood flow through the follicle, but it is not likely that this will significantly affect the steroid output since progesterone was present in high concentrations in the same plasma samples that contained low levels of oestradiol (Furr, 1973). The conclusion that oestradiol is not an important secretion of these large follicles is also supported by the finding that all such follicles together account for only 7-0% of the total ovarian oestradiol content.…”

“…In the domestic fowl, progesterone may be the ovarian hormone that causes the release of LH required for ovulation (Fraps & Dury, 1943;Fraps, 1955Fraps, , 1961Ralph & Fraps, 1959, 1960Furr, 1969Furr, , 1973Peterson & Common, 1971;Kappauf & van Tienhoven, 1972;Furr, Bonney, England & Cunning¬ ham, 1973) though, in mammals, oestrogens may induce the LH surge (Vande Wiele & co-authors, 1970). A similar rôle for oestrogens in the hen has not been fully investigated.…”

Abrupt decrease in daylength and short-term changes in the plasma concentrations of FSH, LH and prolactin in anoestrous ewes

“…The least detectable amounts of hormone were 0-5 ng NIH-LH-S16/ml and 25 ng NIH-FSH-S8/ml. The assay for progesterone was essentially specific (Furr, 1973) and could detect 0-2 ng progesterone/ml with a recovery of 75%.…”