title: Inverse relationships between steroid concentration and volume in preovulatory follicles of the golden hamster.
abstract: In order to investigate variations in the microenvironment of oocytes within a cohort of maturing follicles the follicular volumes as well as the intrafollicular concentrations of oestradiol (E2) and progesterone (P) were measured in the golden hamster. At 10 h before ovulation the follicular volumes varied from 0.009 to 0.037 mm3 (mean +/- SD: 0.0187 +/- 0.0071 mm3; n = 36). Large follicles (greater than 0.025 mm3; n = 8) contained statistically significantly lower E2 and P levels (30.1 +/- 10.4 and 517 +/- 113 mumol/l, respectively) than the medium sized group (less than 0.025 and greater than 0.015 mm3; n =20): 46.9 +/- 16.0 (P less than 0.02) and 919 +/- 264 (P less than 0.0001) mumol/l, respectively. Small follicles (less than 0.015 mm3) showed the highest steroid levels: 97.0 +/- 33.3 and 1590 +/- 517 mumol/l for E2 and P (P less than 0.001 versus the medium sized group values). Correlation coefficients for the steroid concentrations and the follicular volumes appeared to be -0.674 for E2 and -0.612 for P (P less than 0.001). At the time studied a positive correlation between E2 and P concentrations in the follicles was found: r = 0.655 (P less than 0.001). The mean ratios of intrafollicular over serum steroid concentrations appeared to be approx 36 x 10(3) in the case of E2 and about 17 x 10(3) in the case of P. These results clearly show that there is an inverse relationship between follicular volume and intrafollicular steroid concentrations. The presence of a fine regulatory mechanism for a collective maturation of follicles is hypothesized.
authors.affiliation: Medical Faculty, Catholic University, Department of Obstetrics and Gynaecology, Nijmegen, The Netherlands.
authors.forename: H J
authors.initials: HJ
authors.lastname: Goverde
authors.forename: E M
authors.initials: EM
authors.lastname: Aarden
authors.forename: L A
authors.initials: LA
authors.lastname: Bastiaans
authors.forename: C M
authors.initials: CM
authors.lastname: Thomas
authors.forename: R
authors.initials: R
authors.lastname: Rolland
mesh_terms: D000818:Animals; D006224:Cricetinae; D004958:Estradiol / Q000032:analysis*; D005260:Female; D008647:Mesocricetus; D006080:Ovarian Follicle / Q000032:analysis*; D010060:Ovulation; D011374:Progesterone / Q000032:analysis*
chemical_list: D011374:Progesterone; D004958:Estradiol