[Role of adhesive forces in phagocytosis and cell spreading]

A number of demonstrations have been presented in favour of the hypothesis that the main, if not the only, force providing phagocytosis and secretion of rigid (elastic) particles, as well as cell spreading on the substrate is the force (energy) of adhesive interaction between the cellular membrane and substrate. These processes, if carried out only due to adhesion forces, require the following inequality: Wa greater than 2 gamma, where Wa--the work of adhesion per unit of the contact area, gamma--membrane tension. According to the literary data gamma = 0.03--3 mJ/m2, therefore Wa greater than 0.06--6 mJ/m2. Van-der-Waals interaction between the membranes or the membrane and substrate gives Wa less than 0.1 mJ/cm2. When Wa is of the order of units or even tens of mJ/m2, only intermolecular interactions may arise (hydrogen bonds, ion--ion interaction, etc.) with the energy of about 1 kJ/M and even higher according to the number of bonds per unit of a contact surface. The existence of high Wa values is proved by Phillips (1969) who obtained Wa approximately 10 mJ/m2 for one-day embryo cultures.