			Home About us Contact

Short Microvilli (short + microvilli)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Morphology and histology of the larynx of the common toad Rhinella arenarum (Hensel, 1867) (Anura, Bufonidae)

ACTA ZOOLOGICA, Issue 4 2009
Gladys N. Hermida
Abstract The structure of the larynx of the toad Rhinella arenarum was exhaustively studied. The laryngeal skeleton consists of three bilaterally symmetrical cartilages: the cricoid and two arytenoids. Internally, each half-larynx has an anterior and a posterior chamber. The first chamber is delimited by the epithelium covering the arytenoid cartilage and the anterior membrane. The latter consists of fibro-elastic tissue and contains blood capillaries that, judging by their location and distribution, might serve to maintain vocal cord turgidity. At the level of the cricoid cartilage, two structures are reported here for the first time: the posterodorsal and the anteroventral processes. Both processes are associated with the insertion of the posterior membrane. A cartilaginous rod is located at the free margin of the posterior membrane. This rod appears to support the membrane when the air flows. The distal portion of the larynx communicates with the proximal region of the lung. The epithelium of the laryngeal mucosa contains ciliated cells, goblet cells, secretory cells with short microvilli and neuroendocrine cells immunopositive to PGP 9.5. The results obtained in this study provide new information about the internal organization of the larynx in anurans, which could serve as additional morphological characters for phylogenetic relationships. [source]

M cells and associated lymphoid tissue of the equine nasopharyngeal tonsil

EQUINE VETERINARY JOURNAL, Issue 3 2001
P. KUMAR
Summary The aim of this study was to characterise the morphological and histochemical features of equine nasopharyngeal tonsillar tissue. Nasal and oropharyngeal tonsillar tissue has been described as the gatekeeper to mucosal immunity because of its strategic location at the entrance to the respiratory and alimentary tracts. A combination of light, scanning and transmission electron microscopy has revealed the presence of follicle-associated epithelium (FAE) overlying lymphoid tissue of the equine nasopharyngeal tonsil caudal to the pharyngeal opening of the guttural pouch. Membranous microvillus (M) cells were identified in the FAE on the basis of short microvilli, an intimate association with lymphocytes, cytoplasmic vimentin filaments and epitopes on the apical surface reactive with lectin GS I-B4 specific for ,-linked galactose. CD4-positive lymphocytes were scattered throughout the lamina propria mucosae as well as forming dense aggregates in the subepithelial part. The central follicular area was heavily populated with B lymphocytes and the dome and parafollicular areas contained both CD4- and CD8-positive lymphocytes. CD8-positive lymphocytes were also present in the epithelium and, together with B lymphocytes, in small numbers in the lamina propria mucosae. These observations indicate that the nasopharyngeal tonsil is potentially an important mucosal immune induction site in the horse and an appropriate target forintranasally administered vaccines. [source]

Olfactory metamorphosis in the Coastal Giant Salamander (Dicamptodon tenebrosus)

JOURNAL OF MORPHOLOGY, Issue 1 2005
Jeremy T. Stuelpnagel
Abstract This study examined the gross morphology and ultrastructure of the olfactory organ of larvae, neotenic adults, and terrestrial adults of the Coastal Giant Salamander (Dicamptodon tenebrosus). The olfactory organ of all aquatic animals (larvae and neotenes) is similar in structure, forming a tube extending from the external naris to the choana. A nonsensory vestibule leads into the main olfactory cavity. The epithelium of the main olfactory cavity is thrown into a series of transverse valleys and ridges, with at least six dorsal and nine ventral valleys lined with olfactory epithelium, and separated by ridges of respiratory epithelium. The ridges enlarge with growth, forming large flaps extending into the lumen in neotenes. The vomeronasal organ is a diverticulum off the ventrolateral side of the main olfactory cavity. In terrestrial animals, by contrast, the vestibule has been lost. The main olfactory cavity has become much broader and dorsoventrally compressed. The prominent transverse ridges are lost, although small diagonal ridges of respiratory epithelium are found in the lateral region of the ventral olfactory epithelium. The posterior and posteromedial wall of the main olfactory cavity is composed of respiratory epithelium, in contrast to the olfactory epithelium found here in aquatic forms. The vomeronasal organ remains similar to that in large larvae, but is now connected to the mouth by a groove that extends back through the choana onto the palate. Bowman's glands are present in the main olfactory cavity at all stages, but are most abundant and best developed in terrestrial adults. They are lacking in the lateral olfactory epithelium of the main olfactory cavity. At the ultrastructural level, in aquatic animals receptor cells of the main olfactory cavity can have cilia, short microvilli, a mix of the two, or long microvilli. Supporting cells are of two types: secretory supporting cells with small, electron-dense secretory granules, and ciliated supporting cells. Receptor cells of the vomeronasal organ are exclusively microvillar, but supporting cells are secretory or ciliated, as in the main olfactory cavity. After metamorphosis two distinct types of sensory epithelium occur in the main olfactory cavity. The predominant epithelium, covering most of the roof and the medial part of the floor, is characterized by supporting cells with large, electron-lucent vesicles. The epithelium on the lateral floor of the main olfactory cavity, by contrast, resembles that of aquatic animals. Both types have both microvillar and ciliated receptor cells. No important changes are noted in cell types of the vomeronasal organ after metamorphosis. A literature survey suggests that some features of the metamorphic changes described here are characteristic of all salamanders, while others appear unique to D. tenebrosus. J. Morphol. © 2005 Wiley-Liss, Inc. [source]

Light and Electron Microscope Studies on the Nasopharynx and Nasopharyngeal Tonsil of the Horse

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2001
P Kumar
Light and electron microscope studies were conducted on the nasopharynx and the nasopharyngeal tonsil of 15 young horses. The nasopharynx and nasopharyngeal tonsil was lined with pseudostratified columnar ciliated epithelium and goblet cells. The lymphoepithelium of the nasopharyngeal tonsil was folded forming crypts, the mucosa of which was modified into follicle associated epithelium characterized by stratified cuboidal epithelium, loss of cilia, absence of goblet cells and infiltration of lymphocytes. The lamina propria mucosae of the nasopharyngeal tonsil contained well-developed lymphoid tissue and clusters of seromucus acini. Scanning electron-microscopy revealed a dense mat of cilia covering the nasopharynx and nasopharyngeal tonsil. The follicle-associated epithelium consisted of different populations of microvillus cells in addition to M cells with very short microvilli and a few squamous and intermediate cells. Microvillus cells in the deeper part of the FAE had larger microvilli and their cytoplasm contained a dense population of mitochondria, smooth and rough endoplasmic reticulum, Golgi complexes and lysosomes. The flat surfaced M cell had a more electron-dense cytoplasm and contained small supranuclear vacuoles in addition to the organelles seen in microvillus cells. [source]