Transmission electron microscopic studies of urinary bladder in Polystichum squarrosum fern fed guinea pigs

Transmission electron microscopy (TEM) of urinary bladder epithelium in long-term (602 days) Polystichum squarrosum fern fed guinea pigs was studied. Ultrastructurally, in normal guinea pigs urothelium contained 2–3 layers of cells with oval nuclei. Cytoplasm contained vacuoles, mitochondria, lysosomes and other electron dense organelles. Intercellular spaces were marked in underlying cells with presence of microvilli on cytoplasmic membrane. On higher magnification surface-bordering lumina had crest and hollows giving it typical scalloped appearance. Fusiform vesicles, residual bodies, cell junctions and intercellular spaces were also seen. TEM of the surface bordering lumina of urinary bladder in Polystichum fed guinea pigs showed presence of numerous tonofilaments, degenerated nuclear wall, vacuoles in nuclei; large size vacuolations or cystic spaces, certain electron dense inclusions and degenerated mitochondria, markedly dilated fusiform vesicles and prominent intercellular spaces in cytoplasm. Occasionally, surface urothelium was elevated with excretory degenerated material. Ultrastructural studies indicated that Polystichum squarrosum feeding caused sub-cellular degenerative and necrotic changes in urothelium.