Light Microscopy and Ultrastructure of Body Wall in Leech Haemadipsa zeylanica.

Background information: Leeches are widely distributed worldwide in a diversity of habitats, such as freshwater, seas, desert, and oases. Since literature does not have an elaborate study on histology of leeches, thus emphasis is given to study the histology.

Aim: The aim of this study is to examine the histology of free-living leeches Haemadipsa zeylanica under light microscopy and extended to ultrastructural study under transmission electron microscopy.

Materials and methods: Tissue was fixed in 10% formalin, dehydrated with alcohol, infiltrated and embedded in wax, and thin section was cut using a rotary microtome. Sections were stained with hematoxylin and eosin.

Results: The epithelial layer of cells in H. zeylanica had a thin layer of cuticles covering it. In light microscopy, the epidermis has three types of epidermal cells, namely, glandular cells (Type I, Type II, and Type III), supporting cells (Type IV), and pigment cells (Type V). When the three glandular cells of the body wall of H. zeylanica epidermis were examined under an electron microscope, three types of distinct electron-dense granules were identified. Type I cells with granules, Type II cells with course granules close to the dermis were identified as pear-shaped secretory cells, and Type III cells with electron-dense granules.