Experiments designed by the author for the research of production and reaction of point defects during his stay in eight universities and research institutes for about forty years are reviewed. Two-step aging method elucidated the stability of vacancy cluster nucleus in quenched metals, and the deformation induced vacancies were detected by the aid of quenched-in vacancies. High-voltage electron microscopes were efficiently used as micro-laboratories, especially to do the quantitative electron microscopy to extract fundamental properties of point defects and defect interactions. Fusion neutron irradiation with a neutron source RTNS-II was a unique systematic experiment on defects produced by large collision cascades. Advantage of the use of thin foil samples for neutron irradiation was emphasized. The temperature control in fission reactor irradiation was improved to eliminate the influence of the reactor power. Temperature cycle reactor irradiation became possible, and a multi-section removable rig was constructed for systematic irradiation. The role of freely migrating point defects in microstructure evolution was detected by changing the depth of damage zone with the incidence of self-ions with glancing angles. Finally, the ultra-high-speed plastic deformation gave rise to the anomalous production of vacancies and vacancy clusters, and then to the proposal of plastic deformation of metals without dislocations.