光毒腺的显微和超微结构

OBSERVATION ON MICROSTRUCTURE AND ULTROSTRUCTURE OF THE VENOMOUS GLAND IN STINGRAY (DASYATIS LAEVIGALUS CHU)

为探讨类螫伤机理 ,用光镜和电镜观察了光的毒棘腹外侧纵沟内的毒腺的组织结构。结果表明 :光的毒腺为复层上皮。从基底面到游离面依次为基底层、棘细胞层和嗜酸性细胞层。基底层细胞和棘层的细胞嗜碱性 ,棘细胞间有少量、散在分布的嗜酸性细胞 ;棘细胞的外层至腺上皮的游离面的嗜酸性细胞密集排列。电镜下可见基底细胞有丰富的核糖体。棘细胞内粗面内质网、高尔基复合体等较丰富。嗜酸性细胞内有电子密度低的膜包分泌颗粒 ;接近表面的细胞内颗粒部分融合 ;表层细胞核消失 ,胞质充满融合的颗粒 ,游离面侧的胞膜呈角质样增厚。腺上皮内还可见到黑色素细胞、郎格罕细胞和梅克尔细胞。提示毒腺组织内有两种类型的细胞 ,一类为毒液形成细胞 ,另一类为非毒液形成细胞。嗜酸性细胞内的电子密度低的膜包分泌颗粒成分可能是造成螫伤剧痛及全身症状的关键因素。

In order to study the mechanism of Stingrays Dasyatis laevigalus Chu sting, the structure of the venomous gland of the Stingray was observed under light microscope and electromicroscope. The results showed that the venom tissue was the stratified epithelium in the ventral lateral grooves. The epithelium consisted of about 4 layers of cells from the base to the surface. The cells in stratum basale were basophilic cuboidal cells which rested on the basement membrane. The cells above the stratum basale were polygonal cells with central nucleus and cytoplasm filled with rough endoplasmic reticulum, ribosome, golgi apparatus and tonofibril. There were a few eosinophilic cells in HE staining scattered among the polygonal cells. Eosinophilic cells above the polygonal cells to the surface of the epithelium were about 10 layers and were also polygonal profile and were filled with many membrane bound, electron lucent secretory granules (venom granules)in cytoplasma.Some free ribosomes, rough endoplasmic reticulium, golgi complexes and tonofilament were observed in the eosinophilic cells. Near the superficial cells the venom granules were fused. The superficial cell were flat which cytoplasm were filled with fused venom granules and degenerating mitochondria. The cell membrane next to free surface thickened significantly like keratose. Melanocytes, langerhans cells and merkel cells were also observed in the venom epithelium. The results suggest that the substances in the membrane coated, electron lucent granules in eosinophilic cells may be the key factor in the envenomation by Stingrays.