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

Abstract

We describe the functional morphology of the digestive tract of the Eurasian collared dove, Streptopelia decaocto using anatomical, morphometric, histological, histochemical, and ultrastructure techniques, and relate our findings to the species' dietary niche. Our results revealed that the esophagus is displaced on both sides of the neck and has highly folded tunica mucosa, which confer greater elasticity for efficient swallowing and passage of food to the crop. The proventriculus is delicate and its mucosal layer contains polymorphic glands with dense profound and superficial secretory units that open to the luminal surface by gastric pores. The ventriculus is biconvex and lined with a keratinized koilin membrane. The tubular glands within the mucosal lining include the isthmus, the neck, and the basal segment that comprise chief and basal cells with prominent nuclei. At the cuticle-mucosal interface, pyramidal vertical rodlets of the cuticle are secreted and superficially covered by a thin film of a horizontal matrix. The mucosa of the ileum form pyramidal villi that are oriented perpendicularly to the central lumen. Enterocytes infiltrated with goblet cells make up the epithelial lining of the villi. There are subtle differences in the thicknesses of corresponding tunics together with histochemical reactions of alcian blue (AB) and Masson-Goldner trichrome (MT) for their microstructures. Overall, our findings reveal remarkable convergence of both macro-and microstructures in S. decaocto to other granivorous species, and offer further evidence of the close association between functional morphology and feeding style relative to food swallowing, digestion, and absorption.

Seasonal Variations in the Digestive Tract of the Little Owl, Athene noctua: Anatomical, Histological, and Scanning Electron Microscopical Studies

“…The folds are coated with a non-keratinized stratified squamous epithelium. These results for the macroscopic structure of the esophagus agree with those for other avian species (Ma, 2009; Sagsöz & Liman, 2009; Gelis, 2013; El-mansi et al, 2021). These authors concluded that there is a relationship between the histological structure of the esophagus and the type of nutrition and that the size of the esophageal folds is dependent on the size of the food that the birds swallow.…”

Scanning electron microscopic and histological features of the oral cavity of the Egyptian tortoise (Testudo kleinmanni)

“…Our SEM observations show the presence of the two elongated choanal openings on the middle palatine portion that connect the oral cavity with the nasal cavity, similar to that described in; the Basal Tortoise (Heiss et al, 2011), the semiaquatic giant Asian pond turtle(Lintner et al, 2012) and the semiaquatic Malayan box turtle(Heiss et al, 2008). This connection between the oral and nasal cavities is also described in avian species (Abumandour, El‐Bakary, et al, 2021; Abumandour, Shukry, et al, 2021; El‐Mansi, El‐Bealy, Al‐Kahtani, et al, 2021; El‐Mansi, El‐Bealy, Rady, et al, 2021). Crocodilians, on the other hand, have a complete secondary palate that separates the oral cavity from the nasal cavity (Abramyan et al, 2014).…”

“…The Testudo kleinmanni feeds mainly on a wide diversity of the native Egyptian plants in the dry semi‐desert habitats, ranging from grasses to broadleaf plants such as perennials and herbs, which are also used as hiding places (El Din, 2006; Zwartepoorte, 2015). The oral cavity is the most adaptable structure that has adapted to different ecological conditions and is regarded as a key to understanding each animal species' lifestyle (El‐Mansi, El‐Bealy, Al‐Kahtani, et al, 2021; El‐Mansi, El‐Bealy, Rady, et al, 2021; Iwasaki, 2002). According to our research, neither the U‐shaped upper and lower valve nor the slightly serrated upper and lower lip with their numerous scale‐like projections on their surfaces have ever been described in any tortoise species.…”

“…Furthermore, the tongue is the most distinctive structure of the oral cavity contents, describing the morphological adaptations of each animal species in relation to accessible food particles (Abumandour et al, 2022; Iwasaki, 2002). Contents and relates to the morphological adaptations of each animal species to accessible food materials (El‐Mansi, El‐Bealy, Al‐Kahtani, et al, 2021; El‐Mansi, El‐Bealy, Rady, et al, 2021; Iwasaki, 2002). The tortoise's tongue must be flat and papillary to prevent food materials from escaping from the oral cavity due to the presence of an immobile or slowly movable tongue (Wochesländer et al, 1999; Wochesländer et al, 2000).…”

Prevalencia y parasitemia sanguínea de palomas turcas (Streptopelia decaocto) y huilotas (Zenaida macroura) en Durango, México

“…Las especies exóticas representan una amenaza para la estructura, función e integridad de los ecosistemas (Ferreira et al, 2021), contribuyen a la extinción de algunas especies (Rocha et al, 2021) e introducen agentes infecciosos al ambiente colonizado (Hernandez-Colina et al, 2021). La paloma de collar turca (STRDEC, Streptopelia decaocto) es una especie invasora con amplia distribución en Norteamérica (eBird, 2021). Es un ave relativamente grande (Salazar-Borunda et al, 2019), que compite por alimento y sitios de anidación con la avifauna local (El-Mansi et al, 2021;Koenig, 2020) o bien, puede transmitir enfermedades al ambiente colonizado (Stilmmelmayr et al, 2012).…”