Gross anatomical and scanning electron microscopic studies of the oropharyngeal cavity in the European magpie (Pica pica) and the common raven (Corvus corax)

Abstract

There is no descriptive information about morphology of the oropharyngeal cavity including tongue, palate, and laryngeal region in Corvidae family. This study not only presents the first definitive anatomical description of the structures in the oropharyngeal cavity of magpie and raven but also reviews and compares the scattered information on the morphology of the other avian species available in the literature. In this study, the organs of four birds (two magpies and two ravens) were used. The tongue in magpie and raven was considerably elongated and terminated with an oval-shaped apex. Although the lingual apex in the magpie was divided by fissure, no such bifurcation existed on that of raven. Lingual apex was quite distinctive in both species, and multiple acicular processes covered the apex. These occurrences on the tongue of magpie were replaced by thread-like processes as approaching the lingual body. In raven, these processes were mostly foliated, becoming longer toward the back of the lingua, and denser compared with raven. Moreover, we observed conical papillary crest, which was pointed backward and located between the lingual body and the radix of the tongue and pharyngeal conical papillae around the glottis and palate clefts in both species. There was a transversal fold separating the choanal cleft from the infundibular cleft in raven. Anatomy of the oropharyngeal cavity in the raven and magpie, which are the member of the same family, Corvidae, showed little differences and overall their oral morphological features were excessively similar.

Scanning Electron Microscopic Studies of the Lingual Papillae in the English Horse

“…Many morphological studies on the distribution of lingual papillae on the dorsal surface of the tongue have been conducted in mammalian species [2][3][4]. These morphological studies reported that the characteristics of the tongue in mammalian species are in relation to the lifestyle, diet, and environment in which the mammals live, as well as adaptational and taxonomical features of the animals [2,3,5,6] …”

Relating form to function in the hummingbird feeding apparatus

“…These two flaps are located and oriented at the same place and in the same general direction as the papillary crest in other birds. Nevertheless, these structures do not present caudally directed conical papillae, as is usual in avian tongues (e.g., Erdoğan & Alan, 2012; Erdoǧan, Pèrez & Alan, 2012). In comparison to the width of the tongue, these flaps are greatly elongated laterally in Sicklebill hummingbirds ( Eutoxeres , Fig.…”

“…These flaps are thin and flexible at touch, as well as positioned dorso-laterally forming a V-shaped structure. These flaps in hummingbirds have no parallel among nectar-feeding birds (Lucas, 1894; Scharnke, 1932; Scharnke, 1933; Rand, 1961; Rand, 1967; Bock, 1972; Morioka, 1992; Pratt, 1992; Downs, 2004; Chang et al, 2013), or birds in general (e.g., Erdoğan & Alan, 2012; Erdoğan, Sağsöz & Akbalik, 2012; Erdoǧan, Pèrez & Alan, 2012; Erdoğan & Iwasaki, 2014; Erdoğan & Pérez, 2015). I hypothesize that the alae linguae could aid to move the nectar backwards during its intraoral transport (Rico-Guevara, 2014) and to drag proximally arthropod prey that are caught at different places along the bill length (cf.…”

Macroanatomical and histological study of caecum of the guinea fowl (Numida meleagris) using light and scanning electron microscopy

“…Six milimetre thick caecum sections were taken from the paraffin blocks, and painted with Crossmann's triple stain to determine the general histological structure (Culling et al, 1985). For scanning electron microscope images, the apex, corpus and basal parts were separately fixed in 10% formaldehyde solution for 24 hours for modifying caecum tissue samples per methods described by Chen et al (2002), and Erdoğan and Alan (2012). After 2.5% glutaraldehyde was added and allowed to stand for 6 hours, tissues were washed for 10 minutes with 0.1 M phosphate buffer saline (PBS) twice, and five times with 0.1 M buffer solution.…”