Abstract
Background:
The diversity of architecture and histomorphology of the avian alimentary canal significantly influences a wide range of feeding behaviors.

Aim:
This study aimed to examine the histological and histochemical features of the proventriculus and pancreas in adult Timneh African grey Parrot (TAGP).

Methods:
Eight TAGPs were utilized. Subsequently, tissue samples from the Pr and Pa were collected and prepared for histochemical analysis and stained with H&E, PAS, and Masson’s.

Results:
Histological examination revealed that the wall of the proventriculus consisted of four tunicas: tunica mucosa (TM), tunica submucosa (TS), tunica muscularis (TMU), and tunica serosa (TSE). The TM exhibited numerous plicae and sulci lined with simple columnar cells that demonstrated a positive reaction to PAS and Masson’s staining. The TS contained compound tubular glands, which were significantly different from other tunicas. The openings of the proventricular glands were seen through the primary and secondary ducts as raised tubes with consistent tubular outlines. Mucosal folds that reacted positively to PAS and Masson’s staining surrounded the openings. The pancreas showed that the alpha (Ai) islets were characterized by their significantly large size, reaching 2279.83±140.7 µm² with an average diameter of 54.4±13.09 µm, whereas the beta (Bi) islets were characterized by an area of 130.11±8.4 µm² and an average diameter of 13.09±1.08 µm. However, the intermediate mixed (M) islets had an average area of 773.6±71.3 µm² and an average diameter of 26.55±2.79 µm.

Conclusion:
The results contribute to a more thorough understanding of Pr/Pa histomorphology in TAGP and offer insights into potential functional dietary adaptations or behaviors.

Key words: Alpha cell; Beta cell; Islets; Proventriculus; Timneh African grey parrots; Tunica.