石磺科3种贝类皮肤显微结构比较

应用石蜡切片和H.E染色技术,对石磺科(Onchidiidae)3个属的代表物种:瘤背石磺(Onchidium struma)、平疣桑椹石磺(Platevindex mortoni)和里氏拟石磺(Paraoncidium reevesii)的皮肤进行了组织学观察及参数测量比较。结果表明,3种石磺的皮肤虽然厚度不一,但基本结构相似,均由角质膜、表皮和真皮构成。角质膜是一层覆盖于表皮角质层上的蛋白质薄膜;表皮由多层上皮细胞构成,包括角质层、颗粒层和生发层;真皮包括疏松层和致密层,疏松层中嵌有颗粒腺和黏液腺两种腺体。3种石磺的皮肤厚度、各组织相对厚度及腺体数量等均存在差异。将结构差异与石磺的栖息环境进行比较分析后得到:陆栖为主的瘤背石磺皮肤表皮角质化程度高,颗粒腺发达;以水栖为主的里氏拟石磺表皮角质化程度相对低,黏液腺发达;而水陆两栖的平疣桑椹石磺,皮肤角质化程度介于前述二者之间,颗粒腺与黏液腺均不发达。研究结果体现了三者不同的生态适应特征,也为深入探讨海洋无脊椎动物从海洋向陆地进化的研究提供形态学依据。

Comparative Histology of the Skin from Three Species of Onchidiidae

The amphibiotic mollusca Onchidiidae are ideal species for the study of evolution from sea to land in marine invertebrates. In this paper, we choose three representative species of Onchidiidae, Paraoncidium reevesii, Onchidium struma and Platevindex mortoni, which live in shallow water, intertidal zone and supratidal zone respectively. We speculate that, with the change of habitats, the structure of their skin which has the function of respiration must have differences. Therefore, we observe the skin microstructure of three species via paraffin section and hematoxylin-eosin staining and also compare the skin parameters via JMP10.0 statisticalSsoftware. The results showed that, the basic structures of skin are almost the same among three species, which are made up of cuticular membrane, epidermis and dermis. Cuticular membrane covers on the surface of the skin, which is made up of protein. Dermis was composed of stratum spongiosum and stratum compactum. The stratum spongiosum abounded with two types of glands: mucus gland and granular gland. However, there were interspecific differences which include skin thickness, the number and the size of glands and so on. After the comparison between the structural difference and habitat environment, we concluded that O. struma, which mainly lives on terrestrial habitats, has a higher degree of keratinization and a larger number of glandular glands. Compared to O. struma, the mainly aquatic species P. reevesii has a thinner stratum comeum, while its number of mucus gland is the highest. As for the amphibian P. mortoni, the keratinizational degree of its skin is the medium and two kinds of glands are also not developed well. These results reflect three different ecological adaptive mechanisms and also provide the morphological basis for deeper research about the evolution of marine invertebrate from sea to land.