These anatomical folds go by several different names, including the "valves of Kerckring", "Kerckring's folds", plicae circulares and valvulae conniventes. Kerckring used a microscope made by Spinoza.
These anatomical folds are also known by several alternative names, including Kerckring's valves, circular folds, and conjoining valves. Kerckring utilized a microscope crafted by Spinoza.