Morphohistogenesis of gizzard in fowl (Gallus domesticus)

Abstract

Gizzard was globular in group 2, flattened in group 3 and appeared tendinous in group 4. It extended from rostral third of the abdominal cavity to the rostral limit of the cloaca in group 10. The length and width of the gizzard ranged from 7.00-82.00 mm and 6.40-76.00 mm from groups 2 to 10 respectively. The growth spurts of both the parameters revealed maximum increase in groups 2 to 3. The cross sectional (CS) area increased from 54.00-1150.00 mm² in groups 4 to 10 and revealed maximum (206.45%) and minimum (25.81%) increase in groups 6 to 7 and 8 to 9 respectively. The wall of the gizzard was thickest in comparison to other regions of the digestive canal. It increased from 901.00µm in group 2 to 4 964.00µm in group 10. Tunica muscularis was 4·6 times thicker than the mucosal layer and contributed 59.72-73.28% to the total wall thickness against tunica mucosa (15.84-27.37%). The submucosa was very thin. Papillary character was not conspicuous in gizzard. The tubuloalveolar mucous glands appeared in group 3 and were subepithelially placed. In groups 4 onward on the surface of the epithelium a well developed keratinoid or kiolin layer was present. Folding character of mucosa and density of the connective tissue increased with the advancement of age. In later groups 3-external, middle and internal muscle layers were evident. The numerous fibrocartilaginous plates of variable thickness were embedded in between the muscle bundles of middle layer of the tunica muscularis in posthatch chick. Tunica mucosa (30.925%) revealed maximum mean percentage increase.