Quarterly Journal of Microscopical Science, Vol s3-98, 301-314, Copyright © 1957 by Company of Biologists

A Histochemical Study of the Pigment Cells of the Leech, Glossiphonia complanata

¹ Cytological Laboratory, Department of Zoology, University Museum, Oxford

Glossiphonia complanata was found to contain two types of pigment cell. One is very large, usually globular in section, and is found in the deeper layers of connective tissue near the intestinal caeca. The second type is smaller and occurs only in the subcutaneous region of the body.

The large pigment cell contains very many, regular, pigmented spheres, each of which is about 3µ. in diameter. These spheres have a proteinaceous substrate which is partly composed of tyrosine, arginine, and perhaps some histidine. Histochemical and other tests indicate that the yellowish pigment contained in the spheres is amost certainly a tetra-pyrrol compound, possibly related to the vertebrate bile pigments. The pigmented spheres may contain ‘masked’ iron. It is suggested that these pigmented spheres represent the accumulated waste products of haemoglobin breakdown, and so constitute a ‘kidney of accumulation’.

The subcutaneous pigment cell is typically stellate. Both the cell-body and its numerous branching processes are filled with small brown pigment granules which never exceed Iµ in diameter. This pigment is characterized by extreme insolubility and chemical inertness, suggesting that it is a melanin. It is these cells which are primarily responsible for the colour of the animal.