In addition, the cytoplasm of the amoeba can be differentiated into the ectoplasm and endoplasm. The ectoplasm lies just beneath the cell membrane and is in a gel state due to actin filaments held together by binding proteins. In contrast, the endoplasm is in a fluid state and comprises most of the cytoplasm filling the cell interior. It is much less viscous than the ectoplasm (see Figure 7.1) When an amoeba moves, it extends a pseudopodium so that more cytoplasm streams into the pseudopodium. The interaction of actin filaments in the ectoplasm with the fluid endoplasm causes the endoplasm to contract so that an ectoplasmic tube is formed. This causes the cytoplasm to slide forward and the amoeba moves by extending and flowing into the pseudopodia.