Histopathological observation on the larval midgut cells of the silkworm, Bombyx mori, poisoned by NaF
1995
Zhou, C.H. (Utsunomiya Univ. (Japan). Coll. of Agriculture) | Iwashita, Y. | Fukami, M. | Kawasaki, H. | Kanke, E.
The midgut cells of Bombyx mori larvae, to which NaF was administrated per os, were histopathologically observed in order to follow the process of fluoride poisoning. The first change after the administration of 50 micro gram/ml NaF was the development of smooth and rough endoplasmic reticuli (sERs and rERs) in the cytoplasm of midgut cells. After 48 hr sERs and mitochondria degenerated but these changes were slight and limited to local sites. The midgut epithelia were replaced by new epithelia formed by proliferation of regenerative cells. Successive administration of NaF, however, caused gradual degeneration of the midgut cells which were ultimately disintegrated. Within 12 hr after the administration of 300 microgram/ml NaF, rERs became lamellar and the mitochondrial membranes were degenerated. A large number of vacuoles appeared followed by the formation of large autophagosomes in the cytoplasm. Finally, degenerated cells were emitted into the midgut cavity. The alkaline phosphatase activity in the midgut cells observed histochemically were affected severely by the administration of NaF and diminished more strikingly in the goblet cells than in the columnar cells. These findings suggest that fluoride ion induced a direct injury to the midgut cells accompanying the degeneration of organelles
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