Karl G. Grell

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In order to study the origin of metazoans, we have compared sequences from the 5' end of the large subunit ribosomal RNA of a number of protists, fungi, plants and metazoans, including all diploblastic phyla (sequences of 10 new species have been determined, including that of the placozoan, Trichoplax adhaerens). These sequences were analyzed using distance(More)
1. The cells of the ventral epithelium form no microvilli but a spongy meshwork of fenestrated ledges and folds which may play a rôle in the adhesion of the animal to the substratum and/or in the extrasomatic predigestion of the food. 2. During cell division typical centrioles occur at the spindle poles. 3. The growing egg cells phagocytize projections of(More)
1. The egg cells, or oocytes, of Trichoplax adhaerens probably derive from cells of the ventral epithelium. They leave the epithelial layer and go through their growth phase within the interspace between both epithelia. 2. During the growth phase the egg cells are surrounded by fiber cells, which evidently have a nutritive function. 3. Characteristic of(More)
1. An Hand elektronenmikroskopischer Abbildungen wird die Feinstruktur der Chromosomen verschiedener Dinoflagellaten beschrieben. Die Chromosomen sind fibrillär aufgebaut. Die Verfasser halten an der Möglichkeit fest, die im Schnittbild erscheinende Querbänderung der Chromosomen auf den Verlauf eines „Spiralchromonemas“ zurückzuführen. Der natürliche(More)
Leucodictyon marinum Grell, obtained from tide pools near the Shimoda Marine Research Center (Japan), is a meroplasmodium with flattened cell bodies, enclosed in loricae, and a common reticulopodial network. The cell bodies have a single, excentrically located nucleus which contains a central nucleolus, several heterochromatic areas and a filamentous rodlet(More)
1. Cachon-Enjumet's (1961) attempt to interpret the nuclear division of the radiolarian, Aulacantha scolymantha, as a typical, though superficially modified mitosis is subject to criticism. There is no evidence for differences between the numerous chromosomes of this species. The identification of nucleolus organizing chromosomes is inconclusive since(More)
Reticulosphaera socialis GRELL, a protist from the Caribbean coast of Mexico, has a life cycle consisting of a benthic and a pelagic phase. The benthic phase is the dominating part. It is represented by the meroplasmodium, a cellular association which consists of the spherical cell bodies and a common reticulopodial network. Each cell body is surrounded by(More)
1. The fine structure of the tentacle of the suctorian Acineta tuberosa is described. 2. Organelles originally called “missile-like bodies” which stick to the pellicle of the knob of the tentacle are now termed haptocysts. By these haptocysts the tentacle is attached to the prey. 3. Our results partially supported by earlier investigations allow to discuss(More)