Epidermis and sensory receptors of Temnocephala minor (Plathelminthes, Rhabdocoela, Temnocephalida): an electron microscopic study

Abstract

The epidermis, rhabditic glands and receptors of the commensal flatworm Temnocephala minor are described using electron microscopic techniques. The epidermis is syncytial and non-ciliated at the anterior body end; it bears folds, microvilli and other structures which differ according to the body side. The nuclei are located intraepithelially and distally from the basal membrane. Long cilia occur at the posterior end anteriorly from the sucker. All receptor structures described belong to a single morphological type and stand in groups arising from epidermal pits. On the tentacles these groups are regularly distributed. Each receptor has a single cilium and a long rootlet. More than 15 000 receptors of this type have been estimated to occur on the surface of a single medium-sized specimen of T. minor. Although the total number of receptor structures appears very high, the number of different receptor types is extremely low in comparison to other taxa of flatworms.& b d y :Abbreviations bl basal lamina · bm body musculature · bu bulges of the epidermis · ci cilium/cilia · ep epidermis · gr grana · mo mouth-opening · mu musculature · mv microvilli · re receptor · rh rhabdites · ro ciliary rootlet · sd septate desmosome · su sucker · te tentacle& / f n -b l o c k :

Hazard Analysis of Exotic Pathogens of Potential Threat to European Freshwater Crayfish.

“…None of these are considered to be significant pathogens of the freshwater crayfish hosts from which they were described, and therefore present an obvious significant risk to European freshwater crayfish if introduced. However, concerns have been expressed about the potential loss of biodiversity caused by co-translocation of competitor metazoan commensals with freshwater crayfish (MITCHELL and KOCK, 1988;AVENANT-OLDEWAGE, 1993;XYLANDER, 1997;QUAGLIO et al, 1999).…”

Ultrastructural study of the epidermis in two free‐living Platyhelminthes, Mesostoma viaregginum and M. productum (Rhabdocoela, Typhloplanida)

“…Ciliation shows variability within the Rhabdocoela; the entire body is covered by cilia in most free-living rhabdocoels (Tyler & Hooge 2004;Culioli 2006), whereas ciliation is limited to some areas of the body in ectosymbiotic rhabdocoels such as the Temnocephalida (Rohde 1987;Williams 1992;Xylander 1997). On the other hand, the presence of microvilli in M. viaregginum and M. productum is a constant feature of the turbellarian epidermis (Rieger 1981;Rieger et al 1991;Tyler & Hooge 2004).…”

“…In this article, we describe the epidermis of two species of free‐living typhloplanids, Mesostoma viaregginum K olasa 1976 and M. productum (S chmidt 1848) L euckart 1854, and compare the data with those of other Rhabdocoela. Little information is currently available on the detailed epidermal ultrastructure of free‐living Platyhelminthes; ectosymbiotic taxa have been studied with much more attention (Rohde 1987; Rohde & Watson 1988, 1990a,b; Rohde et al 1988a; Joffe et al 1995a,b; Xylander 1997; Joffe & Cannon 1998). Photomicrographs of the epidermis of several typhloplanid species have been published by Bedini & Papi (1974) and Rieger (1981).…”

First description of collar receptors in Temnocephalidae (Platyhelminthes)

“…The ultrastructure of sensory cells in Platyhelminthes has been studied in detail, and, as a result, several types of epidermal receptors have been described (Ehlers 1985; Rieger et al . 1991; Rohde 1994; Xylander 1997; Pfistermüller and Tyler 2002). In ciliated receptors, uni‐ or multiciliated dendritic processes protrude from bipolar neurones whose cell bodies are in the parenchyma surrounding the brain (Reuter and Gustafsson 1995).…”

“…1995a,b; Rohde and Watson 1995; Damborenea and Cannon 2001). The receptor most commonly found is the typical monociliary receptor, with cross‐striated rootlets (Williams 1975, 1977, 1980, 1982, 1994; Rohde 1987; Xylander 1997; Joffe et al . 1998a,b).…”