title: [Morphofunctional study of the organization of the peripheral parenchyma of Acoela Oxyposthia praedator].
abstract: The ultrastructure of undifferentiated cells in the peripheral parenchyma of Oxyposthia praedator was studied, along with the ways of their differentiation. The type I cells (3.5-4.0 microns in diameter) undergo mitotic division, while the type II cells (9 microns in diameter) produce specialized cells of the parenchyma. At the beginning of secretory cell differentiation one cistern of the rough endoplasmic reticulum (RER) is formed by the outer membrane of the nuclear envelope, the formation of other cisternae follows. The Golgi complex is formed simultaneously. The differentiated secretory cells are characterized by the abundance of RER cisternae and Golgi complexes. In the course of differentiation of other cell types RER cisternae are formed by several portions of the nuclear envelope. The Golgi complex appears in cells 12-14 microns long. The differentiation of digestive cells is characterized by autophagy. Autophagosomes are formed by RER cisternae. The consecutive stages of autophagosome formation are described. Using a cytochemical reaction revealing acid phosphatase the process of digestion of the autophagosome content was followed.
authors.affiliation: Zoological Institute RAS, St. Petersburg.
authors.forename: T G
authors.initials: TG
authors.lastname: Markosova
authors.forename: Iu V
authors.initials: IuV
authors.lastname: Mamkaev
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D018870:Endoplasmic Reticulum, Rough / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000648:ultrastructure; D008938:Mitosis; D012867:Skin / Q000033:anatomy & histology / Q000166:cytology; D014419:Turbellaria / Q000033:anatomy & histology* / Q000166:cytology / Q000648:ultrastructure