[Monoamine- and peptide-containing elements in the nemertine digestive tract]

Area of Science:

• Neurobiology
• Invertebrate Zoology
• Histology

Context:

• The digestive system of nemertines, or ribbon worms, is innervated by various cell types containing biologically active substances.
• Previous research has not comprehensively detailed the localization and morphology of these neurochemical elements within the nemertine digestive tract.

Purpose:

• To provide the first detailed comparative histological data on the localization and morphological characteristics of catecholamine-, serotonin-, neurotensin-, and FMRFamide-containing elements in the digestive system of White Sea nemertines.
• To investigate species-specific variations in the distribution of these neurochemical elements along the pharynx, esophagus, and midgut.

Summary:

• Utilizing fluorescent histochemistry and immunohistochemistry, this study examined five nemertine species from three genera.
• Intra- and subepithelial cells containing biologically active substances were identified, with processes extending into the basal and subepithelial nerve plexuses and potentially contacting the digestive tract lumen.
• Distinct species-specific patterns were observed in the localization of these cells relative to the digestive tract's length and epithelial layers.

Impact:

• This research offers foundational data for understanding the neurochemical control of digestion in nemertines.
• The findings contribute to comparative neurobiology and may shed light on the evolution of digestive system innervation in invertebrates.
• Identifies potential functional roles for monoamine and peptide signaling in invertebrate gut physiology.