Histological and histochemical studies of the esophagus and stomach in two types of birds with different feeding behaviors

Abstract

The present work aims to investigate the morphometrical, histological, and histochemical, aspects of the esophagus and stomach in two different Egyptian birds having different food habits. The animals under investigation are Kingfisher (Halcyon smyrnensis), and Hoopoe (Upupa epops). These birds were caught from Abou-Rawash Constituency and Nile Delta in Egypt. The birds were dissected; after which the esophagus and stomach were fixed and stained for the comparative histological study. From the current results, it was revealed that, there are some morphometric differences between kingfisher and hoopoe in both esophagus and stomach. The esophagus wall in Kingfisher composed of only three layers or tunics: mucosa, muscularis and adventitia arranged from the inside to outside, referring to the absence of tunica submucosa;whereas, the esophagus of the Hoopoe consists of four distinct functional layers; mucosa, submucosa, muscularis and the outermost serosa. Stomach in the two studied birds is divided into two parts, glandular or true stomach (proventriculus) and the muscular stomach or gizzard (ventriculus). The glandular stomach showed moderate differences in length and width between kingfisher and hoopoe.The mucosa of proventriculus in the kingfisher consists of number of large compound folds which appear as finger-shaped structures with gastric pits; mucous cells are most conspicuously distinguished by their "empty" appearance. While, the mucosa of proventriculus in the hoopoe have both parietal cells and chief cells which occur in the middle portion of gastric glands. The gizzard wall has a thick keratinized layer called koilin, the secretion of the gizzard glands forms the koilin in hoopoe but in kingfisher the gizzard wall is small and very thin keratinoid lining.

Comparative anatomical, histometrical, and histochemical study of esophagus between ring-necked parakeet (Psittacula krameri) and black-shouldered kite (Elanus caeruleus)

“…The mucosa in the cervical esophagus of the Black-shouldered Kite consisted of nonkeratinized stratified squamous epithelial. These results were consistent with Shehan (23), who studied the esophagus in geese, and Abd-Elnaeem (25), who studied the esophagus in the King fisher. While in the Ring-necked parakeet, mucosa consisted of keratinized stratifies squamous epithelium.…”

Macro‐ and microstructures of the digestive tract in the Eurasian collared dove, Streptopelia decaocto (Frivaldszky 1838): Adaptive interplay between structure and dietary niche

“…In herbivorous or granivorous birds, the proventriculus ranges from being remarkably long and spindle‐shaped in Anas querquedula and Clangula hyemalis (Działa‐Szczepańczyk, 2005; Hanafy et al, 2020), to tubular in Anas platyrhynchos and conical in Columba livia domestica (Hassan & Moussa, 2012). In birds of prey, the proventriculus is comparaively larger than in herbivorous species but also varies in shape, being fusiform in Falco subbuteo (Abumandour, 2014), pear‐shaped in Elanus caeruleus (Hamdi, El‐Ghareeb, Zaher, & Abuamod, 2013), and saccular in Halcyon smyrnensis (AbdElnaeem, Elshaer, & Rady, 2019).…”

Developmental events and cellular changes occurred during esophageal development of quail embryos

“…It is interesting that embryonic quail esophagus lacked the skeletal muscles, unlike the higher (mammalian) and lower species (aquatic and reptiles). The esophagus is devoid of striated muscles in wild avian species such as Rock Dove, Collared Dove, Rose-ringed Parakeet, Kestrel, House Sparrow and Linnet 68 , mallard, spot-billed duck, Ural owl and Hodgson's hawk-eagle 69 , and other birds, Kingfisher ( Halcyon smyrnensis ) and Hoopoe ( Upupa epops ) 70 and chicken 71 . Thus, it seems that involuntary control of the esophagus is unique feature of avian species.…”