粘虫蛾复眼背、腹区视杆结构的差异

根据光学和电子显微镜的观察,粘虫蛾复眼背、腹区域的视杆结构具有以下主要差异:1)背方小眼视杆的长度短于腹方小眼视杆的长度。2)在横切面上,背方小眼视杆的中段近似方形。该段间细胞的视小杆为三角形,每个具有平行排列的微绒毛。整个视杆包含两个互相垂直的微绒毛轴。腹方小眼视杆的中段为风扇形。间细胞的视小杆为“V”字形,微绒毛排列不平行。3)背方小眼基细胞的视小杆几乎位于气管反光层远侧,而腹方小眼甚至延伸到气管反光层内。 在背方和腹方小眼视杆的内段,每个间细胞的微绒毛均平行,且排列在基细胞的大形视小杆周围。更深层,在其它细胞的轴突均已相继出现的水平上,基细胞的大形视小杆仍然可见。 最后,对形态上的特点,在功能上可能具有的一些意义也进行了初步讨论。

STRUCTURAL DIFFERENCE OF RHABDOMS IN THE DORSAL AND VENTRAL OMMATIDIA OF THE ARMYWORM LEUCANIA SEPARATA WALKER

Light and electron microscopic observations reveal that the structure of rhabdoms in the dorsal ommatidia of Leucania separata Walker is different from that in the ventral ommatidia in several aspects: 1) The length of rhabdom in the dorsal ommatidia is shorter. 2) In cross section, the middle part of the dorsal rhabdom is nearly square and contains triangular rhabdomeres of the medial cells provided with parallel microvilli. There are two microvillus axes perpendicular to each other. The middle part of the ventral rhabdom is lobate, and contains V-shaped rhabdomeres of the medial cells without parallel microvilli. 3) In dorsal ommatidia the rhabdomere of the basal cell is almost situated in the outer side of the tapetum, while in ventral ommatidia it extends even into the tapetum.At the proximal part of the rhabdom of both the dorsal and ventral ommatidia, the distal cell and the medial cells have parallel microvilli arranged in the periphery of the large rhabdomere of the basal cell. At deeper level where the axons of all other cells have just appeared in succession, the large rhabdomere of the basal cell still can be seen.The possible functional significance of the structural difference is briefly discussed.