The photoreceptor of diamondback moth, Plutella xylostella L. includes
compund eyes and ocelli. The submicroscopic structure of those organs and
the development of compound eye as the pigment migration were studied with
the light microscopes and mcrospectrophotometer.
A compound eye of diamondback moth is composed of 1500-2000 ommatidia.
Each ommatidium consists of a cornea, crystalline cone, crystalline tract,
two principal pigment cells, six accessory pigment cells end eight
retinular cells which include 1 basal retinular cells. The cornea is
covered with nipples and composed of 19 layers. The microvilli of 7
retinular cells form together the central rbabdom. The rbabdomere of the
8th retinular cell is located near the basement membrane and does not
contribute to the rbabdom rod.
The pigments of the principal pigment cells, accessory pigment cells and
the retinular cells would migrate when exposed to various intensities or
wavelengths of light. The nucleus of the retinular cells never changed
their positions. The light-adapted eye of diamondback moth belongs to the
apposition type while the dark-adapted eye belongs to the superposition
type.
In addition to the large compound eyes, the diamondback moth possesses two
sjmple ocelli on the dorsal region of the head. Each ocellus is composed
of a cornea, corneal crystalline cone, one layer of corneageneous cells
and many layers of Taiwan cells. The retinular cells can be divided into
three parts, the rhabdom is in the upper portion while the nucleus in the
lower portion. The middle portion of retinular cell contains a great
number of organelles, such as mitochondria, rough endoplasmic reticulum,
glycogen granules and may irregular-shaped electron dense granules.
小菜蛾的視覺感光器包括複眼和背單眼，文中除描述該等器官的內外微細構造外 ，還
研究複眼的發育以及對光適應所發生之色素顆粒移動現象等。
小菜蛾的複眼由1500∼2000個小眼構成，每一小眼具有層狀角膜、晶錐體、2 個 主色
素細胞，6 個副色素細胞以及8 個小網膜細胞。角膜上有乳突體，晶錐體底部延 伸成
晶體束，7 個小網模細胞之微絨毛所形成的桿狀體癒合成一桿狀體，而基膜小網 模細
胞之小桿狀體單獨存在於基底膜上方。7 個小網模細胞束上細下粗，在其膨大的 部位
形成正六角形柱，每個柱壁外具6∼7縱走氣管，其節狀構造明顯，唯氣管腔因塌 陷而
消失。眼底氣管之管腔大，內部有褶縐。基底膜為多孔狀，其下方為神經髓質構 造。
小菜蛾之主、副色素細胞及小網模細胞內之色素顆粒，在不同光度下有移動現象 ，但
小網模細胞核不會變換位置，亦即不參與移動現象。由於色素會移動，因此其明 適眼
為並列成像眼，而暗適眼則為重疊成像眼。在紅綠藍光下，色素移動之位置不同 於明
適眼和暗適眼，因此不同波長的光亦會影響色素顆粒之位置。
複眼發育之情況，依其外型上之變化人為地將其分成4 期，在此期間內細胞發生 聚集
、分化、伸長等變化，最後成型，整個發育期始自結繭前，而於羽化前完成。
小菜蛾之背單眼具角膜、角膜晶錐體、單層角膜晶體原細胞及多層小網模細胞。 小網
模細胞可分成3 部份，上段具桿狀體，中段充滿粒線體、粗糙內質網、肝糖顆粒 及不
規則形狀之電子緻密顆粒等，下段則為小網模細胞核之位置。