Histological and histochemical study on the stomach (proventriculus and gizzard) of black-tailed crake (Porzana bicolor)

Black-tailed crake is a little known species of bird in the rallidae family. its natural habitat is subtropical or tropical moist montane marshes at heights around 2100m. black-tailed crake looks for food on the grass-land,picking up small grasshoppers,land-shells and small worms. in this study,the structure of the proventriculus and gizzard of adult black-tailed crake were examined at light microscopic level by using hematoxylineosin (h&e),and special staining for mucins i.e.,periodic acid schiff (pas),alcian blue (ab ph 2.5),ab-pas and combined aldehyde fuchsin- alcian blue (ph 2.5) (af-ab). the results revealed that the epithelium of the proventriculus invaginated to form the simple tubular glands,which showed a weak positive reaction with pas stain but an intense positive reaction with ab (ph 2.5) stain. with the ab (ph 2.5)-pas and af-ab (ph 2.5) staining procedures,the simple tubular glands appeared blue and purple in color,respectively,owing to the presence of sulfated mucins. the compound tubular glands were made up of 8-10 conical or oval lobules and accounted for 77.8%-80.4% of the radius of the proventriculus. the cells lining the secretory ducts and central cavities of the compound tubular glands showed intense positive reactions with all the histochemical stains,indicating a mixture of neutral and acidic mucins occurred and the acidic mucins were carboxylated. however,the cells of corpus glandulae showed negative reactions for mucins. in the proventriculus-gizzard junction,there were nearly no mucins and the compound tubular glands were absent. the surface of gizzard was covered by a layer of rough pas-positive cuticle. the cells lining the tips and the crypts of the glands of gizzard were covered by a layer of carboxylated mucins. the other parts of the gizzard showed negative reactions for mucins. copyright 2015 zoological society of pakistan.