The Pallial Organs of Haliotis Asinina Linnaeus (Gastropoda : Haliotidae)

The pallial organs of Haliotis asinina are composed of gills, osphradium, hypobranchial gland, kidney and heart. The bipectinate paired gills are on the left and right sides of the mantle cavity. The gill epithelium is composed of ciliated columnar cells and occasional mucous cells. The paired osphradia are long, slender and lie anteriorly on each side of the mantle near the gills. The ciliated sensory epithelial cells are very tall and closely packed. The paired hypobranchial glands are fused and lie along almost the entire length of the mantle. The left hypobranchial gland is more prominent than the right one. They are composed of mucous gland cells. The paired kidneys are at the postero-dorsal part of the mantle and lie anteriorly to the heart. The right kidney contains tubulo-asini with light squamous or cuboidal epithelial cells. The left kidney contains densely packed irregular cuboidal epithelial cells. The heart is at the posterior end of the mantle connecting to the gills and is composed of one ventricle and two auricles. The wall of the auricles contains strands of muscle and fibrous tissue whereas the ventricle has thick muscular walls.