Physiologic cell necroses
Springer Online Journal Archives 1860-2000
Summary Mice embryos from day 9 to 15 p.c. have been studied by 1. Supravital staining of the whole embryo with nile blue sulfate. 2. Light and 3. Electron microscopic investigation of serial sections from the longitudinal axis of the back of the trunk. Nile blue sulfate staining revealed segmental necroses in the back of mice embryos centrally between the intersegmental arteries. Necroses appeared in the cranial myotomes and extended to the caudal ones during the days 9 to 13 p.c. By light microscopy the necroses extended in the centre of the myotome to the ventromedial margin. Electron microscopy revealed in this area myoblast-like cells rich in filaments, arranged in parallel without striation. A part of these myoblasts were electron-opaque and the nucleus was no longer evident. Forming vortices of filaments, these cells on the cranial and caudal end of the myotomes ceased fusion with the more centrally situated myoblasts. Vortices of filaments were also found in phagolysosomes of macrophages on day 12 p.c. On the same day of gestation we found an unsegmented myoblastema with irregular long myoblasts and striated polynuclear muscle fibres, arranged parallel to the neural tube. Between and parallel to the muscle fibres elongated individual cells could be seen, growing necrotic. Their nuclei were electron-dense with the chromatin clumping cap-like on the inner nuclear membrane. Fragments of myofibrils, corresponding approximately to sarcomeres, were dispersed irregularly as filament logs in the cytoplasm. Logs of filaments were bent at an obtuse angle, partly showing remnants of Z line material. In this stage of necrosis cells were phagocytized by macrophages. After disintegration of the segmental arrangement in scleroblastemata and myoblastemata a segmental rearrangement was not achieved by segmental shifting or by necrotic liquefaction zones. Whether the described cell necroses are due to differentiation, or even to phylogenetic causes is discussed.
Type of Medium: