Das Bewegungsverhalten der Coelomzellen von Psammechinus miliaris bei der Wundheilung (Echinodermata)

Abstract

In the sea urchin P. miliaris application of time lapse photography allows a study of the very slow movements of coelom cells during the healing process of small wounds on the surface of the calcareous skeleton near the periproct. For observation and time lapse photography LEITZ-Ultropak objectives were used (incident light). Ambulacral feet, spines and pedicellaria were removed, and the animal was fixed in three places in a ring of plexiglass by means of three little screws, which touched the equator of skeleton. The rate of time transformation was 1/240 to 1/480. The film reveals the behaviour of coelom cells, which move out the skeleton to the surface of the small experimental region. Within several hours the white "polished" surface is covered with hundreds of red-brown amoebocytes; only these are visible on the white lime-ground; they have no function in the healing process, which takes place below the surface of the "primäre Wundverschluß" and therefore cannot be observed. There are three main types of coelom cells: red-brown amoebocytes, "körnchenführende Zellen" (white amoebocytes) and leucocytes ("netzbildende" or "skelettbildende Zellen"); the flagellated cells may be neglected here. In order to be able to study the behavior of the three main types of coelom cells, the "primäre Wundverschluß", i. e. the total cell-covering of the wound, is removed and torn into microscopic fragments. These are studied (time lapse) under normal optical conditions (transmitted light). The slides show many "aggregates" of different sizes, single cells and little calcareous concrements torn off the skeleton. The aggregates, even the big ones, exhibit slow locomotion and change their positions considerably. If the distance of two aggregates becomes small enough, they fuse. In these cases a loose cell bridge between the two aggregates is formed. Sometimes no union occurs, although the distance is very small. Even big aggregates suddenly show considerable contractions if spreading has preceded. All movements and place changing of cell-aggregates are caused by contractions and dilatations of the plasmatic network which forms the cellular basis. Little wounds in the newly built "Wundverschluß" scratched with a lancet, heal within several hours. Time lapse shows passive movements of small calcareous fragments, which by chance sometimes enter the small wounds, where they help and accelerate the closing of the injury. The fragments are fixed on the edge of the wound by newly produced lime. Skeleton building coelom cells ("netzbildende Coelomzellen") come up in batches from the depth of the sea urchin's skeleton; each cell contains lime crystals. © 1965 Biologischen Anstalt Helgoland.