This volume contains the proceedings of the Symposium on Molecular and Cellular Aspects of Periimplantation Processes, held July 15 - 18, 1994, in Boston, Massachusetts. Despite considerable research, the molecular and cellular bases of embryo-uterine interactions are still poorly understood. The papers included in this volume address recent advances in several areas in the field of implantation, including uterine receptivity, hormonal regulation, cell-cell interaction, growth factors/cytokines, immunobiology, and trophoblast invasion.1. Nidation Window: From Basic to Clinic.- 2. Surges of Interest and Progress in Implantation Research: An Overview.- I. Hormonal Regulation.- 3. Regulation of Endometrial Responsiveness to Estrogen and Progesterone by Pregnancy Recognition Signals During the Periimplantation Period.- 4. Hormonal Control of Implantation in Some Carnivores.- 5. Differential Gene Expressions and Programmed Cell Death in the Two Cell Populations Forming the Rat Decidua.- II. Uterine Receptivity.- 6. Uterine Receptivity and Endometrial Secretory Protein Patterns.- 7. Mucins and Proteoglycans as Modulators of Embryo-Uterine Epithelial Cell Attachment.- 8. Blastocysts State of Activity and the Window of Implantation in the Mouse.- III. Cell-Cell Interaction.- 9. Extracellular Matrix Remodeling at Implantation: Role of Hyaluronan.- 10. Cellular Interactions During Implantation in Ruminants.- 11. Active and Passive Morphological Interactions of Trophoblast and Endometrium During Early Implantation.- IV. Growth Factors/Cytokines.- 12. IGF System in Periimplantation Uterus and Embryonic Development.- 13. Cytokine Gene Expression and Distribution of Inflammatory Leukocytes in the Periimplantation Mouse Uterus.- 14. Epidermal Growth Factor Receptor Deficiency Results in Periimplantation Lethality in Mouse.- 15. Estrogen Regulation of Uterine Proliferation: How Many ERRs Are Required?.- V. Immunobiology of Implantation.- 16. Proteinase Inhibitors at the Trophoblasls,