Extracellular matrix of the developing ovarian follicle

Abstract

Ovaries can be considered tissues in which endocrine organs--follicles and corpora lutea--continually grow and regress. Follicles have both epithelial and stromal layers in which cell migration or movement, cell division, specialization and differentiation, and death occur. A fluid-filled antrum develops and at ovulation the epithelial cells undergo an epithelial to mesenchymal transition into luteal cells. Although growth factors and hormones are very important in some of these processes, the extracellular matrix participates in all of them. Importantly, the matrix is diverse in composition and cells rarely behave without reference to the composition and structure of the matrix. When follicles commence growing, the follicular basal lamina changes in its composition from containing all six alpha chains of collagen type IV to only alpha 1 and alpha 2. Perlecan and nidogen 1 subsequently become components of the follicular basal lamina, and there is an increase in the amount of laminin chains alpha 1, beta 2 and gamma 1, at least in cows. Late in follicular development and on atresia some follicles contain laminin alpha 2. On atresia the follicular basal lamina is not degraded as occurs at ovulation, but can be breached by cells from the thecal layer if granulosa cells no longer align it. Other matrix components are present and also change during follicular development. Versican was identified in all the follicular layers and has been found to play a key role together with inter-alpha-trypsin inhibitor, tumour necrosis factor alpha-stimulated gene 6 (TSG-6) and hyaluronan in cumulus oocyte expansion and fertility. Recent studies are directed at investigating the regulation of the matrix and its function in the ovary.

Mechanisms of fibroblast growth factor signaling in the ovarian follicle

“…Antral follicles contain numerous proteoglycans and granulosa cells produce HSPG (Yanagishita & Hascall 1983, McArthur et al 2000. Theca cells are separated from granulosa cells by a basement membrane, which contains perlecan as well as other components, and the levels of these components change with follicle growth (Rodgers et al 2003). In addition, a particular form of extracellular matrix (focimatrix) occurs as aggregates within the granulosa cell layer and which contains perlecan (Irving- Rodgers et al 2004).…”

Estradiol supports in vitro development of bovine early antral follicles

“…Furthermore, LAMA1, LAMB2 and LAMC1 are expressed in bovine follicular basal lamina of healthy antral follicles but have reduced expression in the atretic antral follicle . Rodgers et al (2003), suggesting that decreased type 4 collagen and increased laminin are markers for healthy follicle development. Bovine GCs cultured on type 1 collagen gel exhibit a round shape and enhanced E 2 secretion (Huet et al 2001).…”

Expression of protease nexin-1 and plasminogen activators during follicular growth and the periovulatory period in cattle

“…The granulosa and theca cell layers are separated by the basal lamina, and the theca cells are enclosed in a dense extracellular matrix (ECM). Remodeling of the basal lamina and ECM occurs as follicles expand, and changes in the chemical composition of the basal lamina have been described during follicular development (Rodgers et al 2003). Extensive breakdown and remodeling of the basal lamina and connective tissue of the follicular wall is required for ovulation (Curry et al 2001, Richards et al 2002.…”