PARENT SESSION
GAMETE BIOLOGY AND GAMETOGENESIS - A

Monday, August 2, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(158) EFFECT OF FSH ON THE EXPRESSION OF POLARITY IN GRANULOSA CELLS OF PRE-ANTRAL MOUSE OVARIAN FOLLICLES.

Rodrigues, Patricia ^{1, 2}, Plancha, Carlos², Albertini, David¹, ¹ Tufts University School of Medicine, Boston, MA² Instituto de Medicina Molecular, Lisboa, Portugal

ABSTRACT- While FSH is known to drive the transition of pre-antral to antral follicles, the role of FSH on the establishment and maintenance of the polarized epithelial phenotype in target granulosa cells (GCs) remains unexplored. We have began to assess the role of FSH using a battery of markers for epithelial polarity that includes centrosome positioning (anti -tubulin), microtubule (MT) stability (anti acetylated-tubulin), gap junction integrity (anti connexin-43) and basolateral membrane specializations (anti cadherin and anti -catenin). In unstimulated pre-pubertal 14 day old mice, type 3b-4 follicles characteristically display oocyte oriented (apical) centrosomes and basolateral MTs, -catenin and cadherin, features consistent with a stabilized epithelial phenotype under conditions of low circulating FSH. We tested the effects of a single FSH injection (eCG) by priming animals and comparing epithelial polarity expression both prior to and following eCG on this specific class of follicles, in 6-8 week old mice. Prior to eCG, type 3b-4 follicles resemble, in terms of markers expression those of pre-pubertal animals. Following eCG, this class of follicles exhibited maintenance of polarity in outer GCs. In contrast, cells apposed to the oocyte exhibited realignment of centrosomes away from the oocyte and a reduction in the fraction of acetylated MTs. These results illustrate that the preservation of an epithelial phenotype, which may function in maintenance of paracrine interactions at the oocyte-granulosa interface, is more likely to occur following FSH stimulation in the outer granulosa cells that had established adhesion with the follicle basement membrane. Contrarily these findings imply that the oocyte connected GCs are less able to establish a polarized epithelial phenotype when responding to FSH. Grant Support: This work was supported by Fundacao para a Ciencia e Tecnologia (FCT) #SFRH/BD/6439/2001 (PR), POCTI/ESP/43628/2000 (CEP), March of Dimes Birth Defects Foundation 01-248 (DA)

KEY WORDS: Granulosa Cells, Centrosomes, Pre-antral Follicles, FSH