title: The ultrastructure of the midgut epithelium in millipedes (Myriapoda, Diplopoda).
abstract: The midgut epithelia of the millipedes Polyxenus lagurus, Archispirostreptus gigas and Julus scandinavius were analyzed under light and transmission electron microscopies. In order to detect the proliferation of regenerative cells, labeling with BrdU and antibodies against phosphohistone H3 were employed. A tube-shaped midgut of three millipedes examined spreads along the entire length of the middle region of the body. The epithelium is composed of digestive, secretory and regenerative cells. The digestive cells are responsible for the accumulation of metals and the reserve material as well as the synthesis of substances, which are then secreted into the midgut lumen. The secretions are of three types - merocrine, apocrine and microapocrine. The oval or pear-like shaped secretory cells do not come into contact with the midgut lumen and represent the closed type of secretory cells. They possess many electron-dense granules (J. scandinavius) or electron-dense granules and electron-lucent vesicles (A. gigas, P. lagurus), which are accompanied by cisterns of the rough endoplasmic reticulum. The regenerative cells are distributed individually among the basal regions of the digestive cells. The proliferation and differentiation of regenerative cells into the digestive cells occurred in J. scandinavius and A. gigas, while these processes were not observed in P. lagurus. As a result of the mitotic division of regenerative cells, one of the newly formed cells fulfills the role of a regenerative cell, while the second one differentiates into a digestive cell. We concluded that regenerative cells play the role of unipotent midgut stem cells.
authors.affiliation: University of Silesia, Department of Animal Histology and Embryology, Bankowa 9, 40-007 Katowice, Poland.
authors.forename: A
authors.initials: A
authors.lastname: Sosinka
authors.affiliation: University of Silesia, Department of Animal Histology and Embryology, Bankowa 9, 40-007 Katowice, Poland; Silesian Medical College in Katowice, Mickiewicza 29, 40-085 Katowice, Poland. Electronic address: mrost@us.edu.pl.
authors.forename: M M
authors.initials: MM
authors.lastname: Rost-Roszkowska
authors.affiliation: Charles University, Faculty of Science, Department of Zoology, Vinicna 7, 128 44 Prague 2, Czech Republic. Electronic address: vilim@natur.cuni.cz.
authors.forename: J
authors.initials: J
authors.lastname: Vilimova
authors.affiliation: Institute of Soil Biology, Biology Centre AS CR, Na Sadkach 7, CZ-370 05 Ceske Budejovice, Czech Republic. Electronic address: tajov@upb.cas.cz.
authors.forename: K
authors.initials: K
authors.lastname: Tajovský
authors.affiliation: University of Silesia, Department of Animal Histology and Embryology, Bankowa 9, 40-007 Katowice, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Kszuk-Jendrysik
authors.affiliation: University of Silesia, Department of Animal Histology and Embryology, Bankowa 9, 40-007 Katowice, Poland.
authors.forename: Ł
authors.initials: Ł
authors.lastname: Chajec
authors.affiliation: University of Silesia, Department of Animal Histology and Embryology, Bankowa 9, 40-007 Katowice, Poland.
authors.forename: L
authors.initials: L
authors.lastname: Sonakowska
authors.affiliation: University of Silesia, Department of Animal Histology and Embryology, Bankowa 9, 40-007 Katowice, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Kamińska
authors.affiliation: University of Silesia, Department of Animal Histology and Embryology, Bankowa 9, 40-007 Katowice, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Hyra
authors.affiliation: University of Silesia, Department of Animal Histology and Embryology, Bankowa 9, 40-007 Katowice, Poland. Electronic address: izabela.poprawa@us.edu.pl.
authors.forename: I
authors.initials: I
authors.lastname: Poprawa
mesh_terms: D000818:Animals; D001181:Arthropods / Q000502:physiology* / Q000648:ultrastructure*; D018153:Czech Republic; D004064:Digestive System / Q000378:metabolism / Q000648:ultrastructure; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D013234:Stem Cells / Q000502:physiology / Q000648:ultrastructure
keywords: Digestive cells; Midgut epithelium; Millipedes; Regenerative cells; Secretory cells; Ultrastructure