Advanced reproductive age is associated with changes in ovarian architecture and extracellular matrix composition in the South African cheetah (Acinonyx jubatus)

Cryopreservation of germplasms from endangered species offers a last line of defense against loss of genetic diversity. However, animals under human care live extended lifespans compared to wild counterparts, and our understanding of the influence of aging in endangered species is limited. Therefore, we used the South African cheetah (Acinonyx jubatus) as an ambassador species to understand the influence of age on follicle content and composition of the surrounding extracellular matrix. We performed histological analyses of formalin-fixed paraffin-embedded (FFPE) ovarian tissue from 11 cheetahs (3.85–14.75 years) formerly managed under the San Diego Zoo Wildlife Alliance (SDZWA). Ovarian follicles were visualized by H&E and classified by stage. All follicle stages tended to decrease with age, with a significant decline observed in primordial follicles. We then used histochemical approaches to probe components of the ovarian microenvironment, including iron, elastin, hyaluronan (HA), and collagen I/III. Iron and elastin were enriched near follicles with abnormal morphology and multi-nucleated giant cell (MNGC)-like structures. HA localized throughout the ovary and tended to decrease with age in the tunica albuginea, cortex, and stroma. The tunica and medulla of the cheetah ovary were collagen-rich relative to the cortex. With age, collagen increased in the tunica albuginea and the cortex, whereas it decreased in the medulla. The age-associated increase in collagen was associated with thickening of the tunica. These data demonstrate hallmarks of ovarian aging in the cheetah and will inform how future protocols for follicle recovery from ovarian tissue may need to be tailored based on age of the individual.