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Fig. 6 | BMC Zoology

Fig. 6

From: The cellular basis of bioadhesion of the freshwater polyp Hydra

Fig. 6

Cytochemistry of Hydra basal disc. a Overview of semi-thin Epon section stained for glycans with PAS method. The reaction is stronger in the mesoglea and at the aboral tip [arrows] of the cell. b Magnification of a. Arrows indicate strong PAS reactions. Note the reaction gets stronger towards the aboral end of basal disc cells. c TEM- Periodic acid-thiocarbohydrazide-silver proteinate reaction (the EM-correlate PAS staining) was performed on cryo-fixed basal disc revealing the glycan distribution in the Hydra secretory granules. HSGII react positively in and close proximities of the granule membrane, while HSGIII and IV reacts quite uniformly. d Basal disc section not exposed to Periodic acid but regular thiocarbohydrazide-silver proteinate staining. Note secretory granules do not react to glycan staining. e Longitudinal semi-thin section through the basal disc stained with diamino benzidine and oxidized with Osmiun tetroxide. Endogenous peroxidase activity is strong at the aboral end of the basal disc [arrows] and endodermal lipid granules are dark from osmium fixation [asterisks]. f Longitudinal section of basal disc cells reacted for peroxidase after diamino bencidine staining counterstained with methylene blue and Azur II. Arrows point at some reacted secretory granules located at the most-aboral end of the cells. g TEM- peroxidase staining in chemically fixed basal disc is positive for some Hydra secretory granules II and their neighbouring cytoplasm. Arrows point at the most aboral end cell membrane, region with highly peroxidase activity. h Section from a negative control not exposed to diamino benzidine. Scale bars 100 μm (a), 50 μm (b, e), 20 μm (f), 1 μm (c, d, g, h). Abbreviations: PAS, periodic acid Schiff; POX, peroxidase; en, endoderm; m, mesoderm; bd, basal disc; bdc, basal disc cell; I, Hydra secretory granule I; II, Hydra secretory granule II; III, Hydra secretory granule III, IV, Hydra secretory granule IV; ex, exterior of the cell

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