THE GAMETOGENIC PROCESSES IN A TROPICAL ABALONE, HALIOTIS ASININA LINNAEUS

Abstract

The gonad histology and gametogenic processes of a species of abalones found along the coast of Thailand, Haliotis asinina, were studied by light microscopy using special stainings. The outer gonadal wall is similar in both sexes, and consists of fibro-muscular tissue forming a capsule-like structure. This capsule forms connective tissue trabeculae that partition the gonad into compartments, where gonial and early germ cells are attached to each trabecula to form oogenetic or spermatogenic unit. Within the connectives of trabeculae are vessels that contain haemolymph. Cells in oogenetic process could be classified into six stages according to their histological characteristics: oogonium, and five stages of oocytes, ie., with light basophilia (I), with intense basophilia and oil droplets (II), with primary yolk granules (III), with secondary yolk granules and thin jelly coat (IV), and mature ovum with Z types of yolk granules and fully formed jelly coat (V). The cells in spermatogenetic process could be classified into thirteen stages: spermatogonium, five stages of primary spermatocytes, secondary spermatocyte, four stages of spermatids and two stages of spermatozoa.