PARENT SESSION
OVARY - C

Wednesday, August 4, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(793) TUMOR NECROSIS FACTOR (TNF) MAY BE INVOLVED IN FOLLICULAR ENDOWMENT IN THE MOUSE OVARY.

Greenfeld, Chuck¹, Chen, Ying², Pepling, Melissa², Roby, Kathy³, Babus, Janice⁴, Terranova, Paul³, Flaws, Jodi⁴, ¹ University of Maryland, Baltimore, MD² Syracuse University, Syracuse, NY³ University of Kansas, Kansas City, KS⁴ University of Maryland, Baltimore, MD

ABSTRACT- In the embryonic mouse ovary, germ cell nests form due to incomplete cytokinesis during germ cell proliferation. These nests break down early in neonatal life to facilitate primordial follicle formation. Germ cell nest breakdown (GNB) is thought to result from selective apoptosis of germ cells within nests, which serves to break connections between germ cells to yield individual oocytes that become enclosed within primordial follicles. The regulation of GNB is unknown. Since TNF is expressed in the mouse ovary shortly after birth and is capable of inducing oocyte apoptosis in the neonatal rat ovary, TNF may play a role in regulating GNB. Thus, the objectives of this study were to investigate whether TNF induces oocyte death and GNB in the neonatal mouse ovary, and whether it does so via signaling through its TNFR1 receptor. Ovaries were collected from pups (day of birth) and cultured in supplemented Waymouth's medium with 0-50 ng/ml TNF. After 3 days in culture, ovaries were subjected to histological evaluation of naked oocyte (i.e. oocytes within nests), primordial and primary follicle populations. Ovaries were also collected from TNFR1 deficient (TNFR1 -/-) and wild type (WT) females on postnatal day 7, and subjected to histological evaluation of follicle populations. The results indicate that low doses of TNF did not affect naked oocyte, primordial or primary follicle numbers. In contrast, 50ng/ml TNF caused a significant reduction in the number of naked oocytes (control=365.4+40.6; TNF=168.5+49.7, n=12-14; p<0.05) and primary follicles (control=142.7+16.9; TNF=61.6+13.5, n=12-14; p<0.005). In addition, the percentage of oocytes that were enclosed within primordial/primary follicles was significantly higher in the 50ng/ml TNF treatment group compared to controls (control=67.1+1.2%; TNF=79.0+3.1%, n=12-14; p<0.005). Further, there were no differences in the numbers of primordial, primary or preantral follicles in TNFR1 -/- ovaries compared to WT ovaries (n=5-7; p=0.2). Collectively, these data suggest that TNF may participate in GNB, but that TNFR1 is not necessary for this activity. Supported by NIH 38955, T32HD07170, and a grant from the Women's Health Research Group at the University of Maryland.

KEY WORDS: tnf alpha, germ cell nest breakdown, follicular endowment