Mtow Shodo, Tsutsumi Tadaaki, Masumoto Mika, Machida Ryuichiro
Faculty of Symbiotic Systems Science, Fukushima University, Kanayagawa 1, Fukushima City, Fukushima, 960-1296, Japan.
Faculty of Symbiotic Systems Science, Fukushima University, Kanayagawa 1, Fukushima City, Fukushima, 960-1296, Japan.
Arthropod Struct Dev. 2023 Mar;73:101237. doi: 10.1016/j.asd.2023.101237. Epub 2023 Feb 14.
Zygentoma is an order of wingless insects, representing the sister group of Pterygota and constituting Dicondylia together with Pterygota. Contrasting views exist regarding midgut epithelium formation in Zygentoma. According to some reports, in Zygentoma, the midgut epithelium is entirely derived from yolk cells as in other wingless orders; however, according to other reports, the midgut epithelium is of dual origin in Zygentoma, similar to that in Palaeoptera of Pterygota, i.e., the anterior and posterior midgut epithelia are stomodaeal and proctodaeal respectively, whereas the middle part of the midgut originates from yolk cells. Aiming to provide a sound basis to evaluate the true image of midgut epithelium formation in Zygentoma, we examined the formation of the midgut epithelium in detail in Thermobia domestica, and concluded that the midgut epithelium is exclusively derived from yolk cells in Zygentoma, without the stomodaeal and proctodaeal elements involved in its formation. The participation of the anlagen differentiated at or around the stomodaeal and proctodaeal extremities in the formation of the midgut epithelium (bipolar formation) may be regarded as having first appeared not in Dicondylia but in Pterygota, of which the major part is represented by Neoptera with the midgut epithelium formed through bipolar formation.
衣鱼目是一类无翅昆虫,是有翅亚纲的姐妹群,与有翅亚纲共同构成双髁类。关于衣鱼目昆虫中肠上皮的形成存在不同观点。一些报道称,衣鱼目中肠上皮完全像其他无翅目昆虫一样来源于卵黄细胞;然而,另一些报道则称,衣鱼目中肠上皮具有双重起源,类似于有翅亚纲古翅下纲昆虫,即中肠前后部上皮分别来源于口道和后肠,而中肠中部起源于卵黄细胞。为了为评估衣鱼目中肠上皮形成的真实情况提供可靠依据,我们详细研究了嗜卷书虱中肠上皮的形成,得出衣鱼目中肠上皮仅来源于卵黄细胞,其形成过程中不涉及口道和后肠成分的结论。口道和后肠末端或其周围分化的原基参与中肠上皮形成(双极形成)的情况,可能并非首先出现在双髁类中,而是出现在有翅亚纲中,其中大部分以新翅下纲为代表,其通过双极形成来构建中肠上皮。