Abstract
Distal to the flame cells, the protonephridial tubules of fresh-water planarians are circumferentially composed of at least two cells attached by septate junctions; and may be divided, on the basis of morphological criteria, into three longitudinal regions. The cells of nonciliated ductules and ciliated collecting ducts appear to be absorbing material from the lumen; and a distinct proximal-distal polarity is present in each individual cell. At the proximal pole are concentrated micropinocytotic caveolae with amorphous and structural coats on the luminal and cytoplasmic surfaces, respectively. Proceeding distally, a Golgi complex is situated between the micropinocytotic vesicles and large, basophilic, paracrystaline granules. This unusual polarity is interpreted to be important to the resorptive function of the cells.
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Schedule a callMore From: Zeitschrift fur Zellforschung und mikroskopische Anatomie (Vienna, Austria : 1948)
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