FIG. 12.

Components of staphylococcal cross walls. These sketches (modified from reference 54) give preliminary information about the cross wall components involved in cell division and in the different types of cell separation of staphylococci. (A) Situation during initiation of cell separation. Illustrated is a divided staphylococcus with a newly completed cross wall before cell separation liberates the two daughter cells; however, in order to look inside the cross wall with its divers components, the right daughter cell is depicted separately, at some distance from its normal location. Cell separation is just being initiated by the centrifugally directed lytic activity of the murosomes (MuS) which punch two rows of pores (po) into the peripheral cell wall. In slowly growing staphylococci cell separation takes place along the concentrically arranged rings of the splitting system (Sp) which is synthesized during cross wall formation; in rapidly growing staphylococci cell separation takes place along the spoke-shaped canals (spo) which originate only after completion of the cross wall by the centripetally directed lytic activity of the murosomes. The cross wall material located between the two rows of pores including the splitting system is only destined for cell separation and will be disintegrated; this material can only be considered as being transitory parts of the staphylococcal cross wall. Reference figures, Fig. 4b and 11d. (B) Situation after the onset of cell separation. Illustrated are those parts of a completed cross wall which are located directly beneath the peripheral cell wall (pW). In a first lytic step the murosomes (MuS) have punched, via their centrifugal lytic activity, two circumferential rows of pores (po) into the peripheral wall (upward arrow, left side). These pores in the peripheral wall are then torn apart along the perforation line (right row). In a second lytic step the murosomes attack central parts of the cross wall via centripetally directed lytic actions (downward arrow, left side), resulting in the formation of spoke-shaped canals (spo). Between the presumptive cell walls of the future daughter cells (dW) and the peripheral wall of the mother cell (pW) is the location of the so-called stripping system (Str) which is involved in cell wall turnover. Reference figures, Fig. 10a and b and e to g and Fig. 11c to e.