The Morphological Study of the Midgut Epithelium during the Metamorphosis of Pine Caterpillar

變態에 따른 솔나방(Dendrolimus spectabilis Butler) 中腸上皮의 形態的 考察

The morphological changes of the midgut epithelium during the metamorphosis of pine caterpillar are observed with light and electron microscope, being divided into 5 stages from the 8th instar larva to just after pupation. The midgut epithelium of 8th instar larva is composed of columnar cell, goblet cell, regenerative cell, and endocrine cell. The secretorials are arranged on the nuclear membrane in the columnar cell of the midgut epithelium in the 8th instar larva, and lysosomes are augmented in the apical portion. Cytoplasmic extrusions are observed in the apical surface of columnar cell but they have no cell organells. Nucleus, mitochondria, rER, Golgi complex, and free ribsomes are observed in the regenerative cell. Regenerative cells are differentiated into the form of goblet cell, and vacuoles are gradually increased in the cytoplasm. Just pupa stage, the materials, which appears to be mainly composed of Ca, are observed in the circular form and goblet cavity of regenerative cell are detached to lumen. As a result, it reflects the process of the degeneration of the midgut epithelium that lysosomes are gradually augmented in the columnar cell, that nuclear materials are removed to cytoplasm, and that cytoplasmic extrusions are observed in the apical surface. And though regenerative cells are differentiated into the form of the goblet cell, it is believed that goblet cavity is detached from regenerative cell to the lumen and midgut epithelium of pupa stage is formed.

솔나방의 變態에 따른 中腸上皮의 形態的 變化를 終齡幼蟲類에서 踊化直後까지 5단계로 나누어 光學 및 電子顯微鏡을 사용하여 관찰하였다. 終齡類蟲의 中腸上皮는 圓桂狀細胞, 再生細胞 및 內分泌細胞로 구성되어 있다. 終齡幼蟲의 圓桂狀細胞에서는 核으로부터 유출되는 분비물질이 核膜에 규칙적으로 배열되어 관찰되며, 정단부에서는 lysosome이 점차 증가해 간다. 또한, 遊離綠에서는 微細絨毛사이로 팽출한 細胞質突起가 나타나는데 細胞小器官은 관찰되지 않는다. 再生細胞는 分化가 활발해짐에 따라 杯胞가 있는 杯狀細胞型으로 관찰되며, 細胞質에서는 液胞가 점차 증가한다. 踊化直前에는 Ca의 주성분으로 사료되는 물질이 동심원상으로 나타나며 杯胞는 腸內腔으로 분리된다.幼蟲類의 圓桂狀細胞에서 관찰되는 lysosome의 증가, 核物質의 細胞質로 유출, 遊離綠의 細胞質突起는 幼蟲期 中腸上皮의 退化過程을 반영하고 있다고 사료되며, 再生細胞는 杯狀細胞型으로 分化되지만 杯胞가 腸內腔으로 분리되고저 踊化期의 새로운 中腸上皮를 구성한다고 믿어진다.