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

الملخص EN

The present study aimed to investigate the esophagus's anatomical, histometrical, histochemical aspects in the ring-necked parakeet and black-shouldered kite.

the esophagus in the parakeet was shorter and narrower than the kite esophagus.

the crop was a well-developed sac shape in the parakeet, while the crop was hardly recognizable in the kite.

histological study shows that the esophagus in both species was composed of four layers arranged from inner to outer (mucosa, submucosa, musculosa, finally serosa).

these layers showed variances in the height of the fold, the glands number, and the wall layers’ thickness.

the mucosa in the esophagus of the kite consisted of non-keratinized stratified squamous epithelium, while in the parakeet, mucosa consisted of keratinized stratified squamous epithelium.

the esophageal glands were compound tubuloalveolar in the parakeet, while in the kite, there were simple alveolar glands.

the folds in the kite were longest and contained more esophageal glands, while the parakeet glands were more prominent and had fewer numbers within the submucosa.

the submucosa layer in the parakeet was thicker than that of the kite.

the histochemical results showed a positive reaction of esophageal glands with alcian blue (PH 2.5), while reacting negatively with periodic acid schiff (PAS) stains due to the acidic mucopolysaccharides secretions nature.