No abstract

No abstract

Retzius, Bizzozero, and many others it is now known that in the embryo and adult, in plant and animal, vertebrates and invertebrates, all kinds of cells, before their protoplasm undergoes division, show complicated changes of their nucleus, leading to division. This manner of division is called the indirect division or karyokinesis.It has been observed by Mayzel, Schleicher, and Flemming, that the nuclear fibrils show movement, hence the name karyokinesis. This ELEMENTS OF HISTOLOGY.[chap. n. circulating blood or in blood that has just been removed from the vessels. Their substance is transparent granular-looking protoplasm, containing larger or smaller bright granules. These granules are either of a fatty nature, or, as in some kinds of blood, notably horses', are of a reddish colour, and these corpuscles are supposed by some observers (Semmer and Alexander Schmidt) to be intermediate between red and white corpuscles. The protoplasm of the colourless corpuscles contains glycogen (Ranvier, Schafer).In the blood of lower vertebrates the colourless corpuscles are considerably larger than in mammals. But in all cases they consist of protoplasm, include one, two, or more nuclei, and show amoeboid movement. This may be

No abstract

Medullomyoblastoma is a rare histologic variant of medulloblastoma. Of the 20 cases reported in the literature, 19 were in children ages 2.5 to 10.5 years and one was in a 26-year-old woman. In the reported adult case the myogenic component of the tumor was leiomyosarcomatous. The authors report a case of medullomyoblastoma with a rhabdomyosarcomatous component in a 40-year-old man with light microscopic, immunohistochemical, and ultrastructural findings. The histogenetic theories regarding this tumor include that it is a teratoma, or that the myogenic component arises from the perivascular or leptomeningeal ectomesenchyme, or pluripotential neuroectodermal cells, or endothelial cells. The authors' findings do not elucidate the histogenesis but argue against an endothelial origin of the rhabdomyoblastic component.