US EPA

7350406 

Journal Article 

Concentration of immunoreactive progesterone and androgens in the yolk of hens' eggs (Gallus domesticus) 

Mostl, E; Spendier, H; Kotrschal, K 

2001 

1 

Wiener tierärztliche Monatsschrift
ISSN: 0043-535X 

88 

3 

62-65 

WOS:000168075700001 

The theca and granulosa cells of the follicular wall produce gonadal steroids. We investigated the progesterone and androgene concentrations in the yolk layers to gain information on the concentrations of these hormones, as chicken embryos are exposed to this environment. After extraction, the mean concentrations of immunoreactive progesterone and androgens in the yolk of twenty eggs were measured. In another six yolks, cross-section disks from the whole frozen yolks (2 mm thick) were prepared, six concentric layers separated and the values of progesterone, androstenedione and testosterone determined using enzyme immunoassays (EIAs). The extracts were separated by straight phase HPLC and the immunoreactive substances were determined in all fractions to validate the assays. Using the progesterone EIA, three immunoreactive substances were found. Immunoreactive androstenedione was the dominating androgen. The mean concentrations of immunoreactive progesterone were 13.7 +/- 2.9 mug/yolk and of androstenedione 1.2 +/- 0.7 mug/yolk, respectively. The yolk contained highest progesterone concentrations in the outer layer (693 +/- 55 ng/g). The concentrations decreased reaching 14.1 +/- 8.7 ng/g yolk in the centre. The lowest androstenedione concentrations were measured in the surface layer (61.3 +/- 25.1 mug/g yolk). The values increased reaching a maximum in layer 4 (131.3 +/- 35.7 ng/g) and decreased in the following two layers. We conclude that the steroid concentrations in different layers of the yolk represent the metabolic capacity of theca and granulosa cells during the stages of follicular maturation. 

eggs; birds; progesterone; androgens