Seifert P, Smola U, Schinko I
Zoologisches Institut der Universität, München 2, FRG.
Tissue Cell. 1987;19(1):111-8. doi: 10.1016/0040-8166(87)90062-0.
Within the head capsule of the moth-fly Psychoda cinerea, underlying each of the two compound eyes, are two internal ocelli of different sizes. There are seven photoreceptor cells in Ocellus I and two in Ocellus II. The internal Ocellus I appears clearly different from the retina of the compound eye, by different rhabdom structure, different size of pigment granules and different stability of these pigments to solvents. Ocellus II does not contain any pigment granules. The physiological activity of these photoreceptors is indicated by their well-developed axons, the rhabdom structure, organelles produced by membrane reorganization, and adaptation phenomena. The internal ocelli are former larval stemmata that have been displaced inward during metamorphosis. Presumably they have a stimulatory action on the CNS, in analogy with the dorsal ocelli, which are lacking in Psychoda. It is plausible to credit the internal ocelli with a photosensitive role in the functional complex of pacemakers and circadian rhythm.
在毛蠓（Psychoda cinerea）的头壳内，在两只复眼的每一只下方，有两个大小不同的内单眼。单眼I中有七个光感受器细胞，单眼II中有两个。内单眼I与复眼的视网膜明显不同，其视杆结构不同、色素颗粒大小不同，且这些色素对溶剂的稳定性也不同。单眼II不含任何色素颗粒。这些光感受器的生理活性通过其发育良好的轴突、视杆结构、膜重组产生的细胞器以及适应现象得以体现。内单眼是幼虫时期的原侧单眼，在变态过程中向内移位。推测它们对中枢神经系统有刺激作用，这与毛蠓中不存在的背单眼类似。认为内单眼在起搏器和昼夜节律的功能复合体中具有感光作用是合理的。
