Although the physiological, molecular and genetic determinants that initiate and sustain follicular growth and maturation have received much attention (see reviews by McNatty et al., 1999;McGee and Hsueh, 2000), comparatively little information has been forthcoming with regard to the changes in cellular behaviour that attend the process of folliculogenesis. When viewed in the context of other developmental systems, in which paracrine control of cell differentiation is considered implicitly relative to cell signalling, cell-cell adhesion and cell-extracellular matrix (ECM) interactions, our knowledge of cellular behaviours in the ovarian follicle is lacking, despite the wealth of information available on the role of growth factors and hormones in ovarian follicle development (for a review see Elvin and Matzuk, 1998). Recently, Rodgers et al. (1999 have drawn attention to the role of the ECM during bovine follicle growth as related to changes in the follicular basal lamina that may influence the growth and differentiation of both granulosa and theca cells. Given the