Antral, multi-layered secondary, and secondary follicles were observed in extracted ovarian grafts from the subcutaneous and bursa sites (A–B, C–D). In panel A, surrounding alginate material served to maintain separation of host tissue from follicles transplanted subcutaneously. A representative antral follicle is denoted with an asterisk (*) in panels A and C. Large numbers of primordial and primary follicles were identified in all extracted hydrogels and denoted with a single (*) or double asterisk (**) respectively in panels B and D. Hydrogel implant in panel A–B and C–D contained approximately 360 and 1,100 follicles, respectively. Similar results were observed for alginate hydrogels with follicle populations of ~730 ovarian follicles at both sites. Scale bar: 100 μm.