Comparative Features of the Upper Alimentary Tract in the Domestic Fowl (Gallus gallus domesticus) and Kestrel (Falco tinnunculus): A Morphological, Histochemical, and Scanning Electron Microscopic Study

Abstract

The avian alimentary tract has evolved into different histologic structures to accommodate the physical and chemical features of several food types and flight requirements. We compared the esophagus, proventriculus, and gizzard of the domestic fowl, Gallus gallus domesticus (GGD) and kestrels, Falco tinnunculus (FT) using immunohistochemistry and scanning electron microscopy with various stains and lectins [Dolichos biflorus agglutinin (DBA) and Ricinus communis agglutinin I (RCA120)], and α-smooth muscle actin (α-SMA). The esophagus of GGD demonstrated thickened epithelium, muscularis mucosae, and inner circular longitudinal tunica muscularis layers; moderate outer longitudinal tunica muscularis layers; and a true crop. In contrast, the esophagus of FT showed a thin epithelium, no muscularis mucosae, moderate inner longitudinal and thick outer circular tunica muscularis layers, and no true crop. In the proventriculus, the nature of the secretion in GGD was neutral, but that of FT was acidic and neutral. In the gizzard, the muscle coat of GGD by α-SMA had no muscularis mucosae, unlike FT, which had muscularis mucosae. In summary, there are many histologic differences between GGD and FT to meet their different physiologic needs, such as feeding.

Morphological studies on the prehatching development of the glandular stomach of Japanese quails using light, electron, and fluorescent microscopy

“…It was unclear whether the proventricular glands lie in the lamina propria or within the submucosa. In the present study as well as that of Alsanosy et al 33 on domestic fowls, Bezuidenhout, & Van Aswegen 60 on ostriches, Van Alten& Fennell 61 and Romanoff 18 on chicken embryos, and Liman et al 62 on 1-day-old hatched chicks, the deep tubuloalveolar glands were located in the lamina propria. On the other hand, the studies of on fowls considered the glands to be submucosal Bradley, and Grahame 63 , Toner 64 .…”

Anatomical, histochemical, and immunohistochemical observations on the gastrointestinal tract of Gallinula chloropus (Aves: Rallidae)

“…Differing from the studied species, the esophagus of several avian species including chicken, turkey, quail, pigeon, and dove forms a crop that is used by these birds to store and moisten food prior to its digestion [ 32 ]. A number of birds especially those of carnivorous feeding behavior including kestrel [ 33 ] and owl [ 34 ] have been reported to lack the crop. The crop`s functions in the latter Aves have been suggested to be taken over by the esophagus itself [ 35 ].…”