This book explores insect vitellogenesis, the process of egg yolk formation in insects. The author examines the role of the ovary in this process, with a focus on the uptake of extraovarian vitellogenin by vitellogenic follicles and protein synthesis by the ovary itself during vitellogenesis. The book discusses the structural and functional morphology of the insect ovary, the selective uptake of vitellogenin by developing oocytes, and changes in follicular epithelial cells during vitellogenesis. It also examines the potential role of an intercellular matrix in maintaining diffusion channels for vitellogenin uptake. The book concludes by discussing the significance of these insights for understanding the molecular and cellular mechanisms underlying insect vitellogenesis.