The posthatching development of the quail ovary is a well-organized procedure, involving the formation of different ovarian follicles to achieve its
function of producing steroid hormones and eggs. This study was performed on 20 healthy Japanese quail chicks on the day of hatching and 10,
30, and 50 posthatching. The results show the differentiation of cortical germ cells into oocytes and somatic cells into pre-granulosa cells
surrounding the oocyte, forming primordial follicles. Primary and secondary follicles develop, with possible atresia. The follicular thecal layers
developed, and the interstitial stromal cells close to the follicle differentiate into thecal glands. The ovarian stroma is composed of interstitial
glands, intermediate filaments, and lacunar channels. COX2 reacts with ovarian somatic cells differentiated into granulosa and interstitial
stroma cells. Alpha Smooth Muscle Actin (α-SMA) is a marker of myofibroblast cells, while proliferating cell nuclear antigen (PCNA) indicates
the oocyte development and growth. Caspase-3 is involved in the apoptosis of atretic follicles. These results advance our knowledge of avian
reproduction by giving extensive insight into the posthatching development of the Japanese quail ovary. In conclusion, this research examines
structural changes during the growth of ovaries and follicles at various age stages. Future research will broaden the molecular and genetic
aspects of the developing ovary.