Posthatch developmental changes in the ovary with emphasis on follicular development and atresia in the native chicken (Uttara fowl) of Uttarakhand, India

This experiment was designed to investigate the postnatal development of the ovary in the Uttara fowl chicken and was conducted on 54 apparently healthy female birds divided into different age groups, namely Day 1 and Weeks 1, 4, 8, 12, 16, 20, 24, 28 with six birds each. During postnatal development, the left ovary gradually increased in size and complexity. The segmentation of the ovary started by 4 weeks, follicular eruption by 8 weeks, small liquor follicles (1-5 mm) appeared by 16 weeks, pre-hierarchical follicles by 20 weeks and hierarchical follicles by 24 weeks of age. The cortex was distinctly differentiated from the medulla in the early stage of ovarian development. However, the division between cortex and medulla was gradually obscured with age (transitional stage) and distinction was completely lost in the mature ovary. The different stages of follicular development in the chicken ovary were classified as primordial, primary, growing at Stage I, II and III stromal follicles besides pre-hierarchical and hierarchical surface follicles. The primordial and primary follicles showed cytoplasmic sudanophilic substances, especially in the Balbiani's yolk body, indicating the presence of lipids (Sudan Black B) with no activity for neutral polysaccharides (periodic acid Schiff method). It was observed that apoptotic changes may affect any stage of developing follicle resulting in arrested growth and atrophy. An early form of follicular atresia was the fate of the growth-arrested primordial and primary follicles, whereas the glandular form of atresia was commonly observed in growing follicles arrested at Stages I and II. The scanning electron micrographs unveiled the follicles as hollow oval structures with a follicular lumen lined by the perivitelline membrane (glycoprotein membrane) having lacunae giving a honeycomb-like appearance.