FB2026_03 , released September 17, 2026
FB2026_03 , released September 17, 2026
CV Term Report
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General Information
Term Malpighian tubule Type I cell ID (Ontology) FBbt:00005796 (Fly Anatomy)
Definition Morphologically distinct cell type found throughout the Malpighian tubules. It is a large epithelial cell joined by septate junctions to other Type I cells, with apical microvilli and infolding of the basal membrane. There are small differences between Type I cells in different tubule segments: in the initial segment, the cells have few microvilli and are relatively narrow compared with the larger, flatter cells of the main segment. Type I cells originate from division of the ectodermal Malpighian tubules primordial cells that are found in the junction between the hindgut and midgut. Type I cell proliferation is complete by late stage 13 of embryogenesis. In the mature tubules there are on average 484 Type I cells.[ FlyBase:FBrf0064792 FlyBase:FBrf0091042 FlyBase:FBrf0108479 FlyBase:FBrf0160477 ]
Also Known As "Malpighian tubule principal cell" ; "PC"
Comment These cells are involved in primary urine production via the secretion of K+ into the lumen by a vacuolar-type H+ ATPase transporter and K+/H+ exchanger (Davies et al., 1996; Linton and O'Donnell, 1999).
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Insertions (FBti)EXPRESSION_STAGE_TISSUE_POSITION
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 Malpighian tubule Type I cell (all annotations which use CV term, excluding "NOT" statements)
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Malpighian tubule__
somatic cell_______|
                   specialized Malpighian tubule cell
                    |__Malpighian tubule Type I cell  99 rec.
                        |__adult Malpighian tubule principal cell 68 rec.
                        |   |__adult Malpighian tubule principal cell of stem cell zone(+) 18 rec.
                        |   |__adult Malpighian tubule principal cell of upper tubule(+) 13 rec.
                        |__embryonic Malpighian tubule Type I cell 1 rec.
                        |__embryonic/larval Malpighian tubule Type I cell 27 rec.
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Is a specialized Malpighian tubule cell
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