The microstructure and ultrastructure of the foot of Haliotis diversicolor were studied by means of light, scanning and transmission electron microscopes. The foot consists of three different parts: foot sole, skirt and right adductor muscle. Microscopically, the foot sole is composed of epithelium, connective tissue and muscle tissue. The epithelium of the foot sole is pseudostratified ciliated columnar epithelium. The muscle tissue, which is mainly composed of smooth muscle fibers arranged longitudinally, transversely and obliquely, with connective tissue and serving as a “muscular-hydrostat system”. Two trunks of pedal nerve cords run through the muscle tissue of the foot sole in its longitudinal direction, with transverse commissures between the two trunks and many branches from the pedal nerve cords supplying the skirt and right adductor muscle. The skirt bears tentacles and hillocks around its edge. Each skirt tentacle is enclosed by a simple columnar epithelium which is composed mainly of supporting cells, sensory cells and gland cells. Beneath the epithelium, connective tissue joins relative tightly packed muscles surrounding the central nerve cord. Skirt tentacles have a general structure similar to that of the cephalic tentacles, their functions are in support of the cephalic tentacles for finding food and receiving chemical stimuli around the abalone’s body. The epithelium of the skirt hillocks is also simple columnar epithelium, beneath which there is connective tissue. The structure of the main body of the skirt is muscle tissue, which is the extension of the foot sole. The right adductor muscle, with one end connecting to the foot sole and the other to the shell, is mainly composed of muscle tissue which is histologically similar to the body of the skirt and the foot sole.
Fine structure of the hypobranchial gland of Haliotis diversicolor has been studied by light and electron microscopy. The results showed that the gland is folded pleats organ, which is highly glandular area of the epidermal lining the roof of the mantle cavity. Two such glandular areas, one on each side of the rectum, occur in H. diversicolor. Left one is much larger than fight one. By light microscope, on H-E stained section, four cell types can be divided： cells with weak basophilic fibrillar elements; with acidophilic granular substance; with strong basophiIic fibrillar elements and ciliated ceils. In the basal lamina region under the gland epithelium, there are a few connective tissues. Surface view of the gland could be seen by scanning electron microscope, there are cilia and different kinds of secretions distributed. By transmission electron microscope, supporting cells, sensory cells and seven types gland cells were observed to form the glandular epithelium. Cells are rich in rough endoplasmic reticulum, smooth muscle fiber and nerve endings were found beneath glandular epithelium, between basal lamina.
