Experiments were conducted to identify components of the basal lamina of the ovarian follicle. Pure and intact basal lamina was isolated from preovulatory follicles of the chicken ovary. Some components of the basal lamina could be solubilized with guanidine-HCl (designated Fraction 1) and remaining components with beta-mercaptomethanol containing guanidine-HCl (designated Fraction 2). With Western blot analysis, monoclonal and polyclonal antibodies raised against avian, mammalian, and human proteins recognized proteins in Fractions 1 and 2 of solubilized basal lamina. Thus, antibodies raised against extracellular matrix proteins, laminin, fibronectin, entactin or nidogen, tenascin, heparan sulfate proteoglycan, osteonectin, and Type IV collagen reacted positively with basal lamina proteins. Antibodies raised against the growth factors; epidermal growth factor; acidic and basic fibroblast growth factors; platelet-derived growth factor-AA; transforming growth factor-alpha; transforming growth factor-beta1, -beta2, -beta3, and -beta5; and insulin-like growth factor-I and -II cross-reacted with basal lamina proteins. Similarly, antibodies raised against insulin-like growth factor-binding proteins-2, -3, -4, -5, -6, and -7 cross-reacted with basal lamina proteins. In addition, antibodies generated against matrix metalloproteinases-1, -2, -3, -4, -8, -9, and -13 reacted positively with basal lamina proteins. Furthermore, antibodies produced against tissue inhibitors of matrix metalloproteinases-1, -2, -3, and -4 also reacted positively with basal lamina proteins. Moreover, interleukin-3, granulocyte macrophage-colony-stimulating factor, interferon-gamma antibodies recognized proteins in basal lamina. These observations are consistent with the view that the basal lamina of avian ovarian follicle is a store or source of biologically active molecules, namely growth factors, growth factor-binding proteins, cytokines, matrix metalloproteinases, and their tissue inhibitors. The growth factors could exert major effects on ovarian cell behavior and function, and the enzymes could participate in tissue remodeling during follicular development.