<P> The middle lamella is laid down first, formed from the cell plate during cytokinesis, and the primary cell wall is then deposited inside the middle lamella . The actual structure of the cell wall is not clearly defined and several models exist - the covalently linked cross model, the tether model, the diffuse layer model and the stratified layer model . However, the primary cell wall, can be defined as composed of cellulose microfibrils aligned at all angles . Cellulose microfibrils are produced at the plasma membrane by the cellulose synthase complex, which is proposed to be made of a hexameric rosette that contains three cellulose synthase catalytic subunits for each of the six units . Microfibrils are held together by hydrogen bonds to provide a high tensile strength . The cells are held together and share the gelatinous membrane called the middle lamella, which contains magnesium and calcium pectates (salts of pectic acid). Cells interact though plasmodesmata, which are inter-connecting channels of cytoplasm that connect to the protoplasts of adjacent cells across the cell wall . </P> <P> In some plants and cell types, after a maximum size or point in development has been reached, a secondary wall is constructed between the plasma membrane and primary wall . Unlike the primary wall, the cellulose microfibrils are aligned parallel in layers, the orientation changing slightly with each additional layer so that the structure becomes helicoidal . Cells with secondary cell walls can be rigid, as in the gritty sclereid cells in pear and quince fruit . Cell to cell communication is possible through pits in the secondary cell wall that allow plasmodesmata to connect cells through the secondary cell walls . </P> <P> There are several groups of organisms that have been called "fungi". Some of these groups (Oomycete and Myxogastria) have been transferred out of the Kingdom Fungi, in part because of fundamental biochemical differences in the composition of the cell wall . Most true fungi have a cell wall consisting largely of chitin and other polysaccharides . True fungi do not have cellulose in their cell walls . </P> <P> In fungi, the cell wall is the outer-most layer, external to the plasma membrane . The fungal cell wall is a matrix of three main components: </P>

Name the kinds of organisms that have cells without cell walls