FIG. 13.

Thin sections (a and g) and freeze fractures (b to f) of staphylococcal cells. (a) Cell separation in untreated cells along the small layer of the splitting system without detectable loss of cross wall material. (b) During the separation of untreated cells not even remnants of the concentrically arranged tubuli of the splitting system can be detected on the just-exposed cross wall surfaces of the daughter cells. Only the clefts (arrowheads) are preserved which mark the site of the initial cutting through of the peripheral wall (reproduced with permission from reference 54). (c) After growth in the presence of chloramphenicol (20 μg/ml) and subsequent regeneration in drug-free medium, the concentrically arranged tubuli of the splitting system are preserved on the just-exposed surfaces of the daughter cells (reproduced with permission from reference 44). (d) This untreated cell of S. aureus SA 113 reveals the concentrically arranged tubuli of the splitting system on the cross wall surfaces of both daughter cells during cell separation. (e) After growth in the presence of chloramphenicol (20 μg/ml) and subsequent regeneration in drug-free medium, the next division plane is already initiated beneath the center of the still-preserved concentrically arranged rings of the splitting system (arrowheads) (reproduced with permission from reference 44). (f) In the presence of penicillin (0.1 μg/ml), the murosome-mediated punching of holes into the peripheral wall for cell separation starts in a zigzag-like manner (stars), resulting in the formation of two parallel rows of circumferential pores (reproduced with permission from reference 38). (g) In spite of growth in the presence of penicillin, this murosome just released from the cell appears to be rather well preserved.