Anatomy and ultrastructure of the proboscis in Mesorhynchus terminostylis (Platyhelminthes, Rhabdocoela)
De Vocht, A. (1981). Anatomy and ultrastructure of the proboscis in Mesorhynchus terminostylis (Platyhelminthes, Rhabdocoela), in: Schockaert, E.R. et al. The Biology of the Turbellaria: Proceedings of the 3rd International Symposium held in Diepenbeek, Belgium, 11-15 August 1980. Developments in Hydrobiology, 6: pp. 291-298. https://dx.doi.org/10.1007/978-94-011-2775-2_41 In: Schockaert, E.R.; Ball, I.R. (Ed.) (1981). The Biology of the Turbellaria: Proceedings of the 3rd International Symposium held in Diepenbeek, Belgium, 11-15 August 1980. Developments in Hydrobiology, 6. W. Junk Publishers: The Hague/Boston/London. ISBN 978-94-009-8670-1; e-ISBN 978-94-009-8668-8. XIV, 302 pp. https://dx.doi.org/10.1007/978-94-009-8668-8, more In: Dumont, H.J. (Ed.) Developments in Hydrobiology. Kluwer Academic/Springer: The Hague; London; Boston; Dordrecht. ISSN 0167-8418, more |
| Keywords | Mesorhynchus terminostylis Karling, 1956 [WoRMS]; Turbellaria [WoRMS]
Marine/Coastal | | Author keywords | ULTRASTRUCTURE; ANATOMY; TURBELLARIA; PROBOSCIS; EPITHELIA |
| Abstract | The ultrastructural organization of the proboscis in Mesorhynchus terminostylis is distinctly different from that in other members of the Polycystididae in which it is currently classified. The sheath epithelium is formed by three belts, all with intra-epithelial nuclei. The apical belt of the bipartite cone epithelium has a single intrabulbar nucleus, and the basal belt possesses five insunk nucleiferous cell parts behind the bulb. Six types of glands surface through the epithelia; the three types emerging through the cone epithelium can be homologized with those described for Polycistis naegelii. Only uniciliary receptors are found in the epithelium. The musculature in the bulb has a very loose appearance, and the bulbar septum appears to be a bipartite basement membrane. The septum can be considered the basement membrane of the cone epithelium as if the contractile portion of the inner longitudinal muscles have invaded the epithelium and come to lie between the epithelial cells and the basement membrane. Thus the inner musculature of the bulb is entirely intraepithelial as is the case for Psammorhynchus tubulipenis and Cytocystis clitellatus. The systematic position of M. terminostylis remains uncertain but seems to lie between Psammorhynchus and Cytocystis on one hand and Koinocystididae and Polycystididae on the other. |
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