Identification and Pattern of Primary Sensory Cells in the Body Wall Epithelium of the Tubificid Worm, Limnodrilus hoffmeisteri

Abstract

This study compares the effectiveness of two examination methods suitable for morphological observations, scanning electron microscopy (SEM) and light microscopic NADH-diaphorase (NADP-d) histochemistry, to identify location and distribution pattern of primary sensory cells situated in the body wall epithelium of Limnodrilus hofmeisteri. SEM observations revealed that grouped sensory cells forming two distinct types of sensillas (or sense organs) are scattered over the body surface. The easily identifiable first type (ciliated sensilla) contains numerous penetrative ciliate sensory cells while no ciliate sensory cells were seen in the second type (sensory bud). NADH-d staining proved to be a suitable method to identify both structures further staining solitary sensory cells, and certain sensory fibres that could not be visualised by SEM preparations. Our results show that NADH-d staining, as a histochemical marker of primary sensory cells, is a suitable and effective method to reveal their morphology and distribution pattern in whole mount preparations in the smallest detail, suggesting that the application of this relatively simple and cheap method may contribute to understand the basic organisation and evolution of the peripheral sensory structures of oligochaetes.

Mechanosensory cells in annelid oligochaete Lumbricus terrestris (Linnaeus, 1758): A new insight on worm evolution

“…Five different types of sensory cells in earthworms have been identified based on descriptions of their histology and ultrastructure: phaosomal photoreceptors, penetrative uniciliate and multiciliate sensory cells, nonpenetrative multiciliate sensory cells and basal ciliate sensory cells. These cells can be found in groups called sensory organs or individually (Kiszler et al, 2012; Molnár et al, 2006). Langdon (1895) believed that these isolated sensory cells were single cells functioning as sense organs.…”

Vibration sensitivity in earthworms : surfacing responses to seismic vibrations in Florida and Ontario

“…Similarly, the clitellate worm Branchiobdella pentodonta possesses similar sense buttons that are both uniciliated and multiciliated (Farnesi et al, 1982). Two types of sensory buds (in this case ciliated ad non-ciliated) have been also observed in the freshwater oligochaete Limnodrilus hoffmeisteri, which is an even closer relative of the earthworm (Molnar et al, 2006). These are often arranged in rows near the chetae of this organism, although they can also be found randomly on the body surface, and similar organs have been described in other freshwater oligochaetes (Yanez et ah, 2006).…”