Tissue-level Consequences of Segmental Abnormalities in Hirudo verbana: A Morphological and Histological Approach

This study aimed to investigate the histological and morphological differences between healthy and deformed specimens of the medicinal leech Hirudo verbana, with particular focus on tissue integrity and cellular organization.

We conducted comparative histological analysis using haematoxylin and eosin staining on tissue sections obtained from both healthy and deformed leeches. The evaluation included examination of epithelial layer integrity, muscle tissue organization, secretory cell distribution, and pigment accumulation patterns.

Healthy specimens demonstrated well-preserved epithelial layers with regularly arranged circular and longitudinal muscle fibers. The secretory cells (T1, T2A, and T2B types) maintained normal distribution and activity, while melanin pigment showed limited and organized deposition in connective tissues. In contrast, deformed leeches exhibited significant structural abnormalities including disrupted epithelial layers, disorganized muscle architecture (particularly in circular muscles), and reduced T2B secretory cell populations. Notable accumulation of mononuclear immune cells, accompanied by increased melanin deposition, was observed in association with inflammatory foci. Morphological abnormalities included body segmentation defects, tissue atrophy, functional impairment of suckers, and compromised mobility.

Our findings demonstrate that deformation in Hirudo verbana leads to substantial histological and morphological alterations affecting epithelial integrity, muscular organization, secretory functions, and pigmentation patterns. These changes may significantly impact the leeches' biological functionality and therapeutic potential. Further investigation using immunohistochemical techniques and molecular analyses are warranted to elucidate the underlying mechanisms of these pathological changes.