Microsoft word - 184.doc

Steroid hormones concentration of the preovulatory ovarian follicles of the goose
P. Paściak1, D. Wojtysiak2
1JSR Polska Ltd.,42-510 Wojkowice Kościelne 28, Poland Email ppasciak@a4.pl 2Department of Animal Anatomy, University of Agriculture, 30-059 Kraków, Poland Introduction Ovarian follicles are the most important steroids producing structures of the avian ovary. The ovary of a
mature goose generally contains 7-9 large preovulatory follicles arranged in a follicular hierarchy, several postovulatory
follicles, and numerous small follicles, which have not entered the follicular hierarchy. It has been reported that in avian
preovulatory follicles biosynthesis of sex steroid changes during maturation (Gomez et al., 1998; Lee et al., 1998). The
cell theory for steroid production suggested that granular layer of preovulatory follicles primarily produce progesterone
that are required as substrate for the production of androgen and estradiol by theca layer (Huang et al., 1979). The
recently multiple-cell theory of steroidogenic suggest that theca layer can also synthesize progesterone, androgen and
estradiol independent of granulosa layer (Nitta et al., 1991).
Despite strong interest in bird reproductive system there is little information on the goose ovarian system. Therefore the
aim of the study was to determine concentration of progesterone, estradiol and androgens in different sizes of the
preovulatory follicles.
Materials and Methods The concentrations of steroid hormones (P4 – progesterone, E2 – estradiol and A – androgens)
were determined in isolated theca and granular layer of the three largest preovulatory ovarian follicles of the goose. The
studies were carried out on 12 one-year-old Zatorska geese during the reproductive cycle. Preovulatory follicles (F1, F2
and F3) which had entered the hierarchy were isolated from ovaries approximately after egg was layed and before the
ovulation. Yolk was removed from the tissues and were homogenized. Steroid hormones were measured by RIA
methods (Spectria Orion Diagnostic, Finland).
The concentrations of steroid were computed in pg or ng/mg protein and were expressed as means ± SD. Statistical
differences were calculated using Student’s t-test and Duncan’s new test.
Results Mean steroid concentration data for the study are given in Table 1. The major findings of the present study
were, that in preovulatory follicles of the goose; 1.) maximum level P4 was recorded in granular layer and the
concentration P4 significant increased as follicles matured. In all examined follicles level P4 in the theca layer was significantly lower than the granular layer; 2.) the greatest E2 concentration was observed in the theca layer, and next level E2 was decreased significant with follicular size. In the granular layer the E2 concentration was very low and remained constant during the third and second position in the hierarchy, and declined throughout the first position; 3.)changes in concentrations in the theca and granular layer were similar. There was a gradual decrease in both layersduring follicular maturation.
Table 1 Steroid concentration P4 (ng/mg protein ± SD), E2 and A (pg/mg protein ± SD) in the three largest preovulatory
follicles (F1, F2, F3) of the goose.
Progesterone [ng]
Estradiol [pg]
Androgens [pg]
a, b, c, d, e f - significant p<0,05bs – below sensitivity Conclusions It was concluded that, similar to hen, granular layer of the preovulatory follicles of the goose is the major
source of progesterone while theca layer is the principle source of estradiol. Additionally, in the granular layer
steroidogenic activity dramatic increase while in the theca layer gradual decrease as the follicle approaches ovulation.
References
Gomez Y., Velazquez P. N., Juarez-Oropeza M. A., Pedernera E. 1998. Steroid metabolism in granulosa and theca
interna cells from preovulatory follicles of the domestic fowl (Gallus domesticus). Anim. Reprod. Sci., 52: 81-91.
Huang E. S.-R., Kao K. J., Nalbandov A. V. 1979. Synthesis of sex steroids by cellular components of chicken follicles.
Biol. Reprod., 20, 454-461.
Lee K. A., Volentine K. K., Bahr J. M. 1998. Two steroidogenic pathways present in the chicken ovary: theca layer
prefers ∆5 pathway and granulosa layer prefers ∆4 pathway. Domest. Anim. Endocrinol., 15:1-8.
Nitta H., Osawa Y., Bahr J.M. 1991. Multiple steroidogenic cell populations in the theca of preovulatory follicles of the
chicken ovary. Endocrinology, 129: 2033-2040.

Source: http://www.bsas.org.uk/wp-content/themes/bsas/proceedings/Pdf2003/184.pdf