Cytoplasmic Structure and Contractility in Amoeboid Cells

This chapter discusses the cytoplasmic structure and contractility in amoeboid cells. It describes a select group of cell types and the role of actin in both cytoskeletal and contractile events. Amoeboid movement has been defined mechanistically as cell movement occurring in one of two possible ways: by the use of pseudopodia or by cytoplasmic streaming. The amoeboid cells discussed in this chapter have been separated into three categories based on the nature and extent of changes in cytoplasmic structure and contractility during movement and not on any proposed mechanism of movement. The first category consists of cells exhibiting cyclic and extensive changes in cytoplasmic structure and contractility correlated with amoeboid-like movement. The second category consists of amoeboid cells in which filopodia and small lobopodia predominate and in which cyclic but more localized changes in cytoplasmic structure and possibly contractility occur. The third category of cells includes the various mammalian cells grown in culture and cells that exhibit cell sorting during embryogenesis.