The Y organ of the crab, [formula omitted]: Effects of ecdysterone on the ultrastructure

Abstract

The cells of the Y organ have a large nucleus relative to the cytoplasm. The cytoplasm contains mitochondria and a conspicuous smooth endoplasmic reticulum (ER), but the rough ER and Golgi complexes are not well developed. During premolt the infoldings of the plasma membrane were more highly developed than during any other stage of the cycle. Free ribosomes are more numerous in crabs injected with the molting hormone, ecdysterone, and the smooth ER and Golgi complexes are more developed. Many investigators have studied the molting process of crustaceans. Gabe (1953) first described a glandular organ, which he named the Y organ, and suggested that it is the ecdysial gland of crustaceans, homologous to the prothoracic gland in insects. Echalier (1954, 1955, 1959) showed that the Y organ is indeed involved in the control of ecdysis, having performed did removal and implantation experiments with Y organs of the shore crab, Carcinus maenas . Molting in higher Crustacea is now generally agreed to be hormonally regulated, by the molt inhibiting hormone from the neuroendocrine complex of the eyestalks (the X organ-sinus gland system) and by ecdysteroids from the Y organ. A molting hormone, ecdysterone, also known as beta-ecdysone, crustecdysone, ecdysterone, and 20-hydroxyecdysone, has been isolated Horn, Fabbri, Hampshire and Lowe, 1968; Faux, Horn, Middleton, Fales and Lowe, 1968. The purpose of this study was to determine the effects of edcysterone on the ultrastructure of the Y organ of the crab, Portunus trituberculatus .