This book provides illustrated histological, ultrastructural, and histochemical descriptions of the developing mouse ovary and covers the prenatal ovarian development of five stages (day 14-18), the early postnatal development (day 0, 1, 3, 5 and 7), the immature ovary (week 2, 3, 4 and 6) and mature ovary (week 8). The portrayal of the mature mouse ovary included the description of: 1- the estrous cycle, 2- the anatomy of female genital organs, 3- the pre-ovulatory and ovulatory changes during oocyte maturation, and 4- the transformation of post-ovulatory follicles into corpora lutea. Besides, the book provides illustrated descriptions of the follicular atresia in pre-antral and antral follicles. The histochemical studies included the activity of two enzymes (succinate dehydrogenase and adenosine triphosphatase) and lipid contents in different ovarian components of postnatal ovary. The book includes 115 illustrations in color with texts of essential concepts and comments. It also includes 59 ultrastructural microphotographs and 4 diagrams.This illustrated book will be a helpful guide for under and postgraduate students of Zoology, Medicine, Nursing, and Veterinary Medicine.