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Updated: Feb 16, 2026

Intracellular Recording, Sensory Field Mapping, and Culturing Identified Neurons in the Leech, Hirudo medicinalis
Published on: November 4, 2013
Postembryonic Growth of Two Peripheral Sensory Systems in the Medicinal Leech Hirudo medicinalis
Abstract:
The midbody segments of Hirudo medicinalis have two types of sensory cilia that project from the skin into the surrounding water. These are the proposed mechanosensory S cilia and the putative chemosensory G cilia. The cells bearing these cilia are clustered together into structures known as sensilla. The skin of each midbody segment is externally divided into five annuli. Fourteen large sensilla carrying S and G cilia are found on the central annulus of each segment. Small sensilla carrying only G cilia are found on all five annuli. In this paper we show a positive correlation between the size of a neural sensillum and the number of S and G cilia it contains. Any one leech contains a range of sizes of neural sensilla, but the average area increases with the weight of the leech. In contrast, the annular sensilla show only a modest increase in size with leech weight.
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