This book provides the ultrastructural study of the pituitary–gonadal axis through the electron microscope. It is a compilation of extensive work carried out by Dr. D.A. Bhiwgade and his researchers over the last four decades. It explains the ultrastructural characteristics of pituitary cells in different morphological states and provides a comprehensive approach to identifying the structural and functional distinctions between various pituitary cell types.  The book includes ultrastructural evaluations of the testis and epididymis after different experimental interventions to study the physiological correlations of the organs with spermatogenesis and the consequent structural deformities in sperm. An extensive section of different types of placentae is added for understanding the varied interactions of fetal and maternal tissues in the placental barrier. Placental types seen in bats, shrews, rodents, and monkeys are explained at the ultrastructural level to distinguish the tissue interrelationships within different placental layers. Detailed sketches have been provided to illustrate the correlations between the maternal and fetal tissues in different placental types for better understanding. This book is a ready reckoner and offers guidance to researchers and clinicians in understanding the cellular architecture and intracellular changes associated with various physiological states and clinical conditions of the pituitary, testis, epididymis, and placenta. This book offers assistance to all those using electron microscopy to evaluate cellular and tissue systems.