The morphology and location of lymph nodes from seven species of Odontocetes, of both sexes and different age groups, were described. All animals were derived from stranding events along the North and Northeastern coasts of Brazil. After the identification of lymph nodes in situ, tissue samples were analyzed for light and electron microscopy. Vascular volume density (VVD) and vascular length density (VLD) were evaluated in the mesenteric lymph nodes. Lymph nodes occurred as solitary nodules or in groups, varying in shape and size. In addition to using the nomenclature recommended by Nomina Anatomica Veterinaria, new nomenclatures were suggested based on the lymph nodes topography. Lymph nodes were covered by a highly vascularized and innervated capsule of dense connective tissue, below which muscle fibers were observed, inconsistently, in all studied species. There was no difference in VLD among different age groups. However, VVD was higher in adults. Lymph nodes parenchyma was divided into an outer cortex, containing lymph nodules and germinal centers; a paracortical region, transition zone with dense lymphoid tissue; and an inner medulla, composed of small irregular cords of lymphatic tissue, blood vessels, and diffuse lymphoid tissue. Abundant collagen fibers were observed around arteries and arterioles. Germinal centers were more evident and developed in calves and young animals, being more discrete and sparse in adults. The morphology of lymph nodes in Odontocetes was typical of that observed in other terrestrial mammals. However, new groups of lymph nodes were described for seven species occurring in the Brazilian coast.
The importance of the tongue during feeding, and the limited information on the tongue of most aquatic mammals led us to investigate its morphological aspects in sexually immature and mature Sotalia guianensis. Six tongues were measured and photo-documented after their removal from the oral cavity. The samples were divided into rostral, middle, and caudal regions, and examined using light microscopy and scanning electron microscopy (S.E.M.). Sotalia guianensis tongue presented lateral grooves from the apex to the middle portion, while the anterolateral region presented marginal papillae. Histological characteristics revealed the presence of a keratinized stratified epithelium, salivary glands in the middle and caudal portions of the tongue, and filiform papillae in the caudal region. S.E.M. images revealed the presence of filiform papillae and ducts of salivary glands in the middle and caudal portions of the tongue. We can conclude that the characteristics found in this study may reflect an adaptation to changes in diet after weaning.
Morphological characteristics of the tongue were studied in adult rhea (Rhea americana). The lingual surface and the surface of epithelium-connective tissue interface of rhea tongue were examined macroscopically and by light and scanning electron microscopy. The rhea tongue revealed a triangular aspect, without adjustment of the inferior bill formation, occupying approximately ¼ of the length of the oral cavity. Lingual papilla-like structures were not observed over the lingual surface. The tongue mucosa was composed of a thick non-keratinized stratified squamous epithelium in the dorsal and ventral part, supported by a connective tissue core. The submucosa contained numerous glands with cytoplasmic granules, and luminal secretion was positive for histochemical reaction to Alcian Blue in pH 2.5 and PAS, and negative to Alcian Blue in pH 0.5. Despite the rudimentary characteristic of the tongue in rhea, our results suggest an important role of tongue secretions in food lubrication and humidification during the swallowing process, based on the enormous quantity of lingual glands in the submucosa and the histochemical characteristics of their secretions.
Saimiri sciureus is one of the smallest Cebidae native of Amazon region and also found at the biological reserve of northeast Atlantic forest. It is an omnivore animal, with diversified diet that directly influences the lingual mucosa, which includes certain types of papillae with different organization levels. The present study attempted to describe the morphological and ultrastructure aspects of the dorsal surface of the S. sciureus. Five tongues of de S. sciureus were analyzed from three males and two females who died from natural causes and were obtained from breeding colonies of CENP-Ananindeua-PA. Main macroscopic features were a general triangular shape with a craniocaudal elongation pointed apex. Tissue samples--apex, body, and root of tongue--were fixed in modified Karnovsky solution, following standard scanning protocol, mounted in stubs, coated by gold, and analyzed by Scanning Electron Macroscopy (SEM). Four types of papillae were described: filiform (along all tissue extension with 154 ?m of diameter), fungiform (along all tissue extension with 272 ?m of diameter), vallate [just three units in caudal (dorsal) portion with 830 ?m of diameter] and foliate (one pair at caudolateral surface with ? 13 projections and 3000 ?m in length). Data analysis indicates that the distribution and ultra structural morphology of the S. sciureus lingual papillae are some similar to other primates.
The tongue of birds fills the oral cavity and has a beak-like shape. Morphological studies of birds reveal a correlation between the structure of the tongue and the mechanism of food intake and the type of food. However, several studies have shown morphological differences among the tongues of bird species. The aim of this study was to analyze ostrich tongue morphology and ultrastructural features using scanning electron microscopy. Tongues from 12 adult ostriches were examined. Six tongues were sectioned sagittally into lateral and middle portions, fixed in 10% formaldehyde solution, and examined under light microscopy. The other six samples were sectioned longitudinally, and the dorsal and ventral surfaces were separated, immersion-fixed in modified Karnovsky solution, and examined under scanning electron microscopy. The tongue surface of the ostrich was smooth, without lingual papillae, and covered by stratified non-keratinized epithelium. In the submucosal layer, mucous salivary glands were surrounded by connective-tissue capsules, with septa dividing the glands into lobes. Numerous salivary gland ducts of different sizes and connective-tissue laminae dividing each opening could be clearly seen in scanning electron microscope images. The ventral surface had fewer openings than the dorsal surface. In samples treated with NaOH, connective-tissue papillae from the dorsal region were oriented posteriorly.
Capybara is the largest rodent in the world and displays a seasonally dependent herbivore feeding behavior. Here, we present an anatomical contribution for understand this fact, by light, scanning, and transmission electron microscopy methodologies for tongue tissue analysis. The histological preparations revealed filiform, fungiform, vallate, and foliate papillae on the dorsal mucosa of the capybara tongue. The epithelial layer exhibited a lining of keratinized stratified squamous epithelial cells. The lamina propria was characterized by a dense connective tissue composed of the primary and secondary papillar projections. We also revealed the original aspects of the connective papillae. The shapes of the papillae varied by region of the tongue, and filiform, fungiform, vallate, and foliate papillae and subjacent layers of muscular fibers were observed. Pyriform taste buds occupying the epithelial layer of fungiform, vallate and foliate papillae were identified and the intracellular components of the taste buds and the intracorpuscular amyelinated nerve fibers were observed. The taste buds were characterized by the distribution of granular endoplasmic reticulum throughout the perinuclear area, the Golgi apparatus, and mitochondrial assemblies of various distinct diameters. Mitochondrial accumulation was also observed in the collagen bundle-surrounded amyelinated nerve fibers beside the basal cells. Therefore, these peculiar anatomical descriptions may contribute to understanding the adaptation of the feeding behavior of capybaras in a seasonally changing environment.
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