日本沼虾(Macrobrachium nipponense)孵化前后复眼发育的超微结构研究

Ultrastructure of development of compound eyes before and after hatching in Macrobrachium nipponense

利用电镜技术研究日本沼虾孵化前后复眼发育的超微结构,结果显示:(1)复眼内小眼折光系统包括角膜、角膜细胞及晶锥,晶锥周围有虹膜色素细胞分布。从产卵后第16 d到第Ⅰ期状幼体,小眼角膜厚度和晶锥直径逐渐增大,角膜细胞内细胞器数量逐渐增多;晶锥内电子致密颗粒区域由6块融合为4块,晶锥末端附近出现第8个小网膜细胞。(2)小眼感光系统由8个小网膜细胞组成,小网膜细胞伸出微绒毛组成“十足目型”感杆束,感杆束周围围绕一层较薄细胞质,胞质内外可见胞饮小泡及膜下储泡囊。随着胚胎发育,感杆束直径逐渐增大,小网膜细胞内线粒体、内质网等细胞器数量逐渐增多,并出现多囊体、板膜体、色素颗粒等结构。(3)胚胎发育过程中,小网膜细胞分化过程如下:产卵后第16 d,感杆束周围7个小网膜细胞间空隙较大,中间被第8个小网膜细胞4个分叶隔开,细胞内出现远端色素颗粒;第Ⅰ期状幼体,第8个小网膜细胞位置上升,其它7个小网膜细胞相互间排列紧密,细胞内出现大量近端色素颗粒。

Uhrastructure of development of compound eyes before and after hatching in Macrobrachium nipponense was studled by electron microscopy. The results of this study showed that （ 1 ） the dioptre System of an ommatidium included cornea, comeagenous cell, and crystalline cone surrounded by iris pigmental cells. From 16th day after spawning to the zoea Ⅰ Stage, the thickness of cornea, the diameter of crystalline cone, and the amounts of organdies in comeagenous ceils increased gradually, in addition, the blocks of dense electron granules in crystalline cone changed from 4 to 4 - 8 retinular cell appeared in the end of crystalline cone. （2） The sensate system of an ommatidium composed of 8 retinular cells. Mi- crovilli protruded from retinular ceils maked up of the ＇ Decapoda type＇ rhabdom, which arounded a thin layer of cytoplasm where imbibe vesicles and perirhadomal vacuoles could be seen. With the development, the diameter of rhabdom, the amounts of organelles such as mitochondria, endoplasmic reticulum, increased gradually. Futhermore, lamellar bodies, multivesicular bodies, proximal pigment granule also appeared. （3） Retinular cells have a differential process： at 16th day after spawning, the space between each of seven retinular cells was wide and separated by the four lobes of the eighth retinular cell, and the distal pigment granules appeared; at zoea Ⅰ stage, location of the eighth retinular cell has ascended, which made the other seven retinular cells circled around the rhabdom tightly, a great deal of proximal pigment granules can be seen in retinular cells.