title: Ultrastructure of the midgut and hindgut of Derocheilocaris remanei (Crustacea, Mystacocarida).
abstract: Ultrastructural features and structure of the midgut and hindgut of Derocheilocaris remanei were studied. The large endodermal midgut is differentiated into an anterior midgut and a posterior midgut separated by a conspicuous constriction. Both circular and longitudinal striated muscle bands surround the midgut, while the hindgut only presents longitudinal muscles. The limit between the midgut and the cuticle-lined hindgut is marked by a rectal valve. In cross-section, the short hindgut is triradiate and has a distinct Y-shaped lumen. The hindgut cuticular lining appears interrupted at the tip of every branch of the Y. Three different cell types are found in the midgut epithelium: basally located undifferentiated cells that give rise to the other two specialized cell types; secretory zymogen-like cells responsible for extracellular digestion and located mainly in the anterior midgut; and vacuolated cells, distributed all along the midgut and appearing to have several functions, including absorption, intracellular digestion, and nutrient transport. A single basic cell type forms the hindgut epithelium. The suggested function for the hindgut is the transport and ejection of waste products.
authors.affiliation: Departamento de Biología Animal I, Facultad de Biología, Universidad Complutense, Madrid, Spain. letiziaherrera@ctv.es
authors.forename: L
authors.initials: L
authors.lastname: Herrera-Alvarez
authors.forename: I
authors.initials: I
authors.lastname: Fernández
authors.forename: J
authors.initials: J
authors.lastname: Benito
authors.forename: F
authors.initials: F
authors.lastname: Pardos
mesh_terms: D000818:Animals; D003445:Crustacea / Q000033:anatomy & histology / Q000648:ultrastructure*; D004064:Digestive System / Q000033:anatomy & histology / Q000648:ultrastructure; D008854:Microscopy, Electron