The domestic duck, as a representative of birds living in the water, is considered as a specialist filter-feeder. Behavioral observations of foraging revealed that these birds also use a terrestrial feeding mechanism such as grazing and pecking. This study examined the entirety of the lingual mucosa in relation to the structural adaptations required for this range of feeding activities. The structures on the lateral surfaces of the tongue, the conical and filiform papillae, constitute the food filtration apparatus. The process of pecking involves the spatula-shaped apex of the tongue and a specific horny plate—the lingual nail. In the grazing mechanism, large conical papillae and lamellae in the beak are required. Structures engaged in intra-oral transport include the median groove, lingual combs, the rostral border of the lingual prominence and distinct rows of conical papillae on the lingual prominence. Two types of keratinized epithelia, the ortho- and parakeratinized epithelium, as well as nonkeratinized epithelium cover individual areas of the tongue. The rostral and caudal lingual glands present in the lamina propria of the body, lingual prominence and root of the tongue produce mucus. The specific arrangement of Grandry and Herbst corpuscles form so-called bill-tongue organ monitoring food transportation. Our research confirm that the lingual mucosa in domestic duck is characterized by microstructural species-specific modifications of particular areas of the tongue, which is formed not only under the influence of the filtering mechanism, but also by terrestrial feeding mechanisms such as grazing or pecking.

中文翻译：

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家鸭（Anas platyrhynchos f.domestica, Anatidae）舌头的形态功能研究：LM 和 SEM 研究

家鸭作为生活在水中的鸟类的代表，被认为是一种专业的滤食动物。觅食的行为观察表明，这些鸟类也使用陆上觅食机制，如放牧和啄食。这项研究检查了整个舌粘膜与这一系列喂养活动所需的结构适应性之间的关系。舌头侧面的结构，即锥形和丝状乳头，构成了食物过滤装置。啄食的过程涉及到舌尖和一个特定的角质板——舌钉。在放牧机制中，喙中需要大的锥形乳头和薄片。参与口腔内运输的结构包括正中沟、舌梳、舌突的吻端缘和舌突上明显的成排圆锥形乳突。两种类型的角化上皮，正角化上皮和非角化上皮，以及非角化上皮覆盖舌头的各个区域。存在于身体固有层、舌突和舌根中的舌侧和尾侧舌腺会产生粘液。Grandry 和 Herbst 小体的特定排列形成了所谓的喙器官监测食物运输。我们的研究证实，家鸭舌黏膜的特征是舌头特定区域的微观结构物种特异性改变，这不仅是在过滤机制的影响下形成的，而且还受到陆生摄食机制的影响，例如放牧或啄食。