Statement of Purpose: Decellularization is a promising technique to generate tissue-specific biomaterials for tissue engineering and regenerative medicine. Our group was the first to decellularize an ovary, repopulate it with ovarian cells, and show that the decellularized ovary scaffold supported the function of ovarian cells in vitro and in vivo, as evidenced by secretion of estradiol and inhibin A (1). Despite this success, the use of decellularized tissue scaffolds comes with limitations; specifically, matrix properties and architectures are “locked in," and it is very difficult to control the placement and seeding efficiency of different cell types within the structure. Furthermore, there is another important consideration specific to ovary tissue engineering: maintenance of the 3D architecture of the ovarian follicle, the oocyte surrounded by somatic cells. Maintenance of this 3D architecture is critical for follicle survival and function but cannot be achieved efficiently in decellularized tissue scaffolds due to their fixed porosity. To overcome these limitations, we processed decellularized ovaries into ovary-specific hydrogels compatible with follicle encapsulation and 3D patterning (e.g. micromolding, direct extrusion 3D printing). The goal of this study was the evaluate the structural and mechanical properties of bovine ovary decellularized extracellular matrix (dECM) hydrogels derived from ovarian cortex and medulla and whole ovary, and whether they could be used to support in vitro growth of bovine ovarian follicles, which has been challenging using other biomaterial scaffolds (e.g. alginate, fibrin).