Morphometric and Immunohistochemical Characteristics of the Adult Human Soft Palate Muscles.

The soft palate is the only structure that reversibly separates the respiratory and gastrointestinal systems. Most species can eat and breathe at the same time. Humans cannot do this and malfunction of the soft palate may allow food to enter the lungs and cause fatal aspiration pneumonia. Speech is the most defining characteristic of humans and the soft palate, along with the larynx and tongue, plays the key roles. In addition, palatal muscles are involved in snoring and obstructive sleep apnea. Considering the significance of the soft palate, its function is insufficiently understood. The objectives of this study were to document morphometric and immunohistochemical characteristics of adult human soft palate muscles, including fiber size, the fiber type, and myosin heavy chain (MyHC) composition for better understanding muscle functions. In this study, 15 soft palates were obtained from human autopsies. The palatal muscles were separated, cryosectioned, and stained using histological and immunohistochemical techniques. The results showed that there was a fast type II predominance in the musculus uvulae and palatopharyngeus and a slow type I predominance in the levator veli palatine. Approximately equal proportions of type I and type II fibers existed in both the palatoglossus and tensor veli palatine. Soft palate muscles also contained hybrid fibers and some specialized myofibers expressing slow-tonic and embryonic MyHC isoforms. These findings would help better understand muscle functions.

Isolation and development of bovine primary respiratory cells as model to study influenza D virus infection.

Influenza D virus (IDV) is a novel type of influenza virus that infects and causes respiratory illness in bovines. Lack of host-specific in vitro model that can recapitulate morphology and physiology of in vivo airway epithelial cells has impeded the study of IDV infection. Here, we established and characterized bovine primary respiratory epithelial cells from nasal turbinate, soft palate, and trachea of the same calf. All three cell types showed characteristics peculiar of epithelial cells, polarized into apical-basolateral membrane, and formed tight junctions. Furthermore, these cells expressed both α-2,3- and α-2,6-linked sialic acids with α-2,3 linkage being more abundant. IDV strains replicated to high titers in these cells, while influenza A and B viruses exhibited moderate to low titers, with influenza C virus replication not detected. These findings suggest that bovine primary airway epithelial cells can be utilized to model infection biology and pathophysiology of IDV and other respiratory pathogens.

Proteogenomics Uncovers Critical Elements of Host Response in Bovine Soft Palate Epithelial Cells Following In Vitro Infection with Foot-And-Mouth Disease Virus.

Foot-and-mouth disease (FMD) is the most devastating disease of cloven-hoofed livestock, with a crippling economic burden in endemic areas and immense costs associated with outbreaks in free countries. Foot-and-mouth disease virus (FMDV), a picornavirus, will spread rapidly in naïve populations, reaching morbidity rates of up to 100% in cattle. Even after recovery, over 50% of cattle remain subclinically infected and infectious virus can be recovered from the nasopharynx. The pathogen and host factors that contribute to FMDV persistence are currently not understood. Using for the first time primary bovine soft palate multilayers in combination with proteogenomics, we analyzed the transcriptional responses during acute and persistent FMDV infection. During the acute phase viral RNA and protein was detectable in large quantities and in response hundreds of interferon-stimulated genes (ISG) were overexpressed, mediating antiviral activity and apoptosis. Although the number of pro-apoptotic ISGs and the extent of their regulation decreased during persistence, some ISGs with antiviral activity were still highly expressed at that stage. This indicates a long-lasting but ultimately ineffective stimulation of ISGs during FMDV persistence. Furthermore, downregulation of relevant genes suggests an interference with the extracellular matrix that may contribute to the skewed virus-host equilibrium in soft palate epithelial cells.

Yak (Bos grunniens) Tonsils: Morphological Description and Expression of IgA and IgG.

This study aimed to describe the morphology, expression of IgA and IgG in adult yak tonsils. The 12 clinically healthy yak tonsils [3- to 6-year old, n = 12] were examined for morphology using light, and transmission electron microscopes. Expression of IgA and IgG was measured by qRT-PCR, ELISA, and immunohistochemistry. The results showed that the palatine tonsil, the tonsil of the soft palate, and the lingual tonsil were oropharyngeal tonsils. The stratified squamous epithelia covering them had a thick underlying layer of connective tissue and their crypts were heavily infiltrated by lymphocytes. The pharyngeal tonsil and the tubal tonsil were nasopharyngeal tonsils. The epithelia of them was predominantly pseudostratified columnar ciliary epithelium, which were loosely arranged with a number of desmosomes or intermediate junctions variably connecting them. The expression levels of IgA and IgG mRNA and protein from high to low was in the pharyngeal tonsil, palatine tonsil, tonsil of the soft palate, lingual tonsil, and tubal tonsil, respectively. Interestingly, the expression of IgG was very significantly higher than that of IgA in yak tonsils (P < 0.01). Both the IgA and IgG ASCs were distributed in the subepithelial areas of the non-reticular crypt epithelium, especially areas of pseudostratified columnar ciliary epithelium, the reticular crypt epithelium, lymphoid follicles, interfollicular areas, and with some of the positive cells aggregating around the glands. The results indicated that the tonsils were not only typical secondary lymphoid organs but also lymphoepithelial structures. IgG could be a significant component of mucosal immune responses in yak tonsils. Anat Rec, 302:999-1009, 2019. © 2018 Wiley Periodicals, Inc.

Sensory Innervation of the Human Soft Palate.

The human soft palate plays an important role in respiration, swallowing, and speech. These motor activities depend on reflexes mediated by sensory nerve endings. To date, the details of human sensory innervation to the soft palate have not been demonstrated. In this study, eight adult human whole-mount (soft palate-tongue-pharynx-larynx-upper esophagus) specimens were obtained from autopsy. Each specimen was bisected in the midline, forming two equal and symmetrical halves. Eight hemi-specimens were processed with Sihler's stain, a whole-mount nerve staining technique. The remaining eight hemi-soft palates were used for immunohistochemical study. The soft palatal mucosa was dissected from the oral and nasal sides and prepared for neurofilament staining. Our results showed that the sensory nerve fibers formed a dense nerve plexus in the lamina propria of the soft palatal mucosa. There was a significant difference in the innervation density between both sides. Specifically, the oral side had higher density of sensory nerve fibers than the nasal side of the soft palate. The mean number and percent area of the sensory nerve fibers in the mucosa of the nasal side was 78% and 72% of those in the mucosa of the oral side, respectively (P < 0.0001). The data presented here could be helpful for further investigating the morphological and quantitative alterations in the sensory nerves in certain upper airway disorders involving the soft palate such as obstructive sleep apnea (OSA) and for designing effective therapeutic strategies to treat OSA. Anat Rec, 301:1861-1870, 2018. © 2018 Wiley Periodicals, Inc.

Effect of artificial rearing of piglets on the volume densities of M cells in the tonsils of the soft palate and ileal Peyer's patches.

The high prolificacy of modern hybrid sows has increased the mean litter size during the last decades. However, rearing large litters is challenging and has increased the use of alternative management strategies such as euthanasia of weak piglets, cross-fostering, supplementing piglets with milk, split-nursing and split-weaning. The latter includes artificial rearing on brooders where piglets have ad libitum access to milk replacer. The effect of this artificial rearing on the immune system of the piglet is the subject of various studies. The present study focused on the M cells in the tonsil of the soft palate and in the ileal Peyer's patch (iPP). These epithelial cells are specialized in antigen sampling and play a pivotal role in the induction of adaptive immune responses. The volume densities of the M cells were assessed by stereological analysis of tissue samples from piglets of 0, 3, 8 and 19days of age. During the first three days, piglets suckled the sow, permitting them to ingest colostrum. At the third day, the piglets were either allowed to continue to suckle the sow or were transferred to brooders. The six experimental groups, each containing six piglets, thus consisted of newborn piglets, 3-day-old sow-suckled piglets, and conventionally and artificially reared piglets of 8 and 19days of age. To identify M cells, tissue samples were immersed in 4% phosphate-buffered paraformaldehyde and paraffin sections were immunohistochemically stained against cytokeratin 18. The volume densities of M cells in both the crypt epithelium of the tonsils of the soft palate and the follicle-associated epithelium of the iPPs did not show any difference between the various age groups of conventionally reared piglets. However, values were twice as high in the iPPs compared to the tonsils of the soft palate. In contrast, a decrease in volume densities of M cells was observed in the iPPs of piglets after they had been transferred to commercial brooders (P=0.05), resulting in significantly lower values (P=0.04) in comparison with the age-matched sow-suckled groups. However, this observation did not translate to values of the tonsils where M cell volume densities remained the same in all age and rearing groups. Based on these results, it appears that antigen sampling is possible from birth onwards and is more advanced in the small intestine than in the oropharynx, but possibly lags behind in artificially reared piglets.

Contribution of Underlying Connective Tissue Cells to Taste Buds in Mouse Tongue and Soft Palate.

Taste buds, the sensory organs for taste, have been described as arising solely from the surrounding epithelium, which is in distinction from other sensory receptors that are known to originate from neural precursors, i.e., neural ectoderm that includes neural crest (NC). Our previous study suggested a potential contribution of NC derived cells to early immature fungiform taste buds in late embryonic (E18.5) and young postnatal (P1-10) mice. In the present study we demonstrated the contribution of the underlying connective tissue (CT) to mature taste buds in mouse tongue and soft palate. Three independent mouse models were used for fate mapping of NC and NC derived connective tissue cells: (1) P0-Cre/R26-tdTomato (RFP) to label NC, NC derived Schwann cells and derivatives; (2) Dermo1-Cre/RFP to label mesenchymal cells and derivatives; and (3) Vimentin-CreER/mGFP to label Vimentin-expressing CT cells and derivatives upon tamoxifen treatment. Both P0-Cre/RFP and Dermo1-Cre/RFP labeled cells were abundant in mature taste buds in lingual taste papillae and soft palate, but not in the surrounding epithelial cells. Concurrently, labeled cells were extensively distributed in the underlying CT. RFP signals were seen in the majority of taste buds and all three types (I, II, III) of differentiated taste bud cells, with the neuronal-like type III cells labeled at a greater proportion. Further, Vimentin-CreER labeled cells were found in the taste buds of 3-month-old mice whereas Vimentin immunoreactivity was only seen in the CT. Taken together, our data demonstrate a previously unrecognized origin of taste bud cells from the underlying CT, a conceptually new finding in our knowledge of taste bud cell derivation, i.e., from both the surrounding epithelium and the underlying CT that is primarily derived from NC.

A Comprehensive Study of Soft Palate Development in Mice.

Cleft palate is one of the most common congenital birth defects. Tremendous efforts have been made over the last decades towards understanding hard palate development. However, little is known about soft palate morphogenesis and myogenesis. Finding an appropriate surgical repair to restore physiological functions of the soft palate in patients with cleft palate is a major challenge for surgeons, and complete restoration is not always achievable. Here, we first analyzed the morphology, orientation and attachments of the four muscles of the murine soft palate and found that they are very similar to their counterparts in humans, validating the use of mus musculus as a model for future studies. Our data suggests that muscle differentiation extends from the lateral region to the midline following palatal fusion. We also detected an epithelial seam in the fusing soft palatal shelves, consistent with the process of fusion of the posterior palatal shelves, followed by degradation of the epithelial remnants. Innervation and vascularization are present mainly in the oral side of the soft palate, complementing the differentiated muscles. Cell lineage tracing using Wnt1-Cre;Zsgreenfl/fl mice indicated that all the tendons and mesenchyme embedding the soft palate muscles are neural crest-derived. We propose that the posterior attachment of the soft palate to the pharyngeal wall is an interface between the neural crest- and mesoderm-derived mesenchyme in the craniofacial region, and thus can serve as a potential model for the study of boundaries during development. Taken together, our study provides a comprehensive view of the development and morphology of the murine soft palate and serves as a reference for further molecular analyses.

During development intense Sox2 expression marks not only Prox1-expressing taste bud cell but also perigemmal cell lineages.

Sox2 is proposed to regulate the differentiation of bipotential progenitor cells into taste bud cells. However, detailed expression of Sox2 remains unclear. In this report, Sox2 expression during taste bud development in the fungiform (FF), circumvallate (CV) and soft palate (SP) areas is examined together with Prox1. First, we immunohistochemically checked Prox1 expression in adults and found that almost all taste bud cells are Prox1-positive. During FF development, intense Sox2 expression was restricted to taste bud primordia expressing Prox1 at E12.5. However, at E14.5, Sox2 was intensely expressed outside the developing taste buds resolving to perigemmal Sox2 expression in adults. In the SP, at E14.5, taste bud primordia emerged as Prox1-expressing cell clusters. However, intense Sox2 expression was not restricted to taste bud primordia but was detected widely in the epithelium. During development, Sox2 expression outside developing taste buds was generally down-regulated but was retained in the perigemmal region similarly to that in the FF. In the CV, the initial stage of taste bud development remained unclear because of the lack of taste bud primordia comparable to that in the FF and SP. Here, we show that Prox1-expressing cells appear in the apical epithelium at E12.5, in the inner trench wall at E17.5 and in the outer trench wall at E18.5. Sox2 was again not restricted to developing taste bud cells expressing Prox1 during CV development. The expression patterns support that Sox2 does not serve as a cell fate selector between taste bud cells and surrounding keratinocytes but rather may contribute to them both.

The formation of endoderm-derived taste sensory organs requires a Pax9-dependent expansion of embryonic taste bud progenitor cells.

In mammals, taste buds develop in different regions of the oral cavity. Small epithelial protrusions form fungiform papillae on the ectoderm-derived dorsum of the tongue and contain one or few taste buds, while taste buds in the soft palate develop without distinct papilla structures. In contrast, the endoderm-derived circumvallate and foliate papillae located at the back of the tongue contain a large number of taste buds. These taste buds cluster in deep epithelial trenches, which are generated by intercalating a period of epithelial growth between initial placode formation and conversion of epithelial cells into sensory cells. How epithelial trench formation is genetically regulated during development is largely unknown. Here we show that Pax9 acts upstream of Pax1 and Sox9 in the expanding taste progenitor field of the mouse circumvallate papilla. While a reduced number of taste buds develop in a growth-retarded circumvallate papilla of Pax1 mutant mice, its development arrests completely in Pax9-deficient mice. In addition, the Pax9 mutant circumvallate papilla trenches lack expression of K8 and Prox1 in the taste bud progenitor cells, and gradually differentiate into an epidermal-like epithelium. We also demonstrate that taste placodes of the soft palate develop through a Pax9-dependent induction. Unexpectedly, Pax9 is dispensable for patterning, morphogenesis and maintenance of taste buds that develop in ectoderm-derived fungiform papillae. Collectively, our data reveal an endoderm-specific developmental program for the formation of taste buds and their associated papilla structures. In this pathway, Pax9 is essential to generate a pool of taste bud progenitors and to maintain their competence towards prosensory cell fate induction.

Diverse contributions of Tas1r2/Tas2rs within the rat and mouse soft palate to sweet and bitter neural responses.

Neural responses to sweet and bitter stimuli in the rat and mouse are compared to the expression of the molecular taste receptors, Tas1r2/Tas2rs. Integrated taste responses from the greater superficial petrosal nerve (GSP) innervating the soft palate (SP) and the chorda tympani (CT) nerve innervating the fungiform papillae (FF) were recorded in C57BL mice and SD rats. The sum of the phasic and tonic response magnitudes (SRM) was calculated by summating all relative mean responses to a concentration series of QHCl (10(-6)-10(-2)M) or Suc (10(-4)-1.0M). Molecular expression was analyzed by double-colored in situ hybridization for Gα-gustducin with Tas1r2 or Tas2rs in the SP and FF. The vast majority of cells expressing Tas1r2 or Tas2rs were included in Gα-gustducin-expressing cells in the SP of both species. Unexpectedly, a comparison between species revealed that the SRM from the GSP is not positively correlated with receptor expression in the SP. In the rat SP, the percentage of Tas2rs with Gα-gustducin (Tas2rs/gust, 65%) was twice larger than that for Tas1r2/gust (33%), while the SRM to Suc in the rat GSP was 1.5 times (tonic and phasic) larger than that to QHCl. In the mouse SP, the percentage of Tas2rs/gust (46%) was less than that in the rat and similar to that of Tas1r2/gust (40%). However, the SRM to QHCl in the mouse GSP was 2.4 (phasic) and 4.7 (tonic) times larger than to Suc. On the other hand, threshold to Suc in the rat GSP was 10(-3)M, one log unit lower than in mouse, and the threshold to QHCl in the mouse GSP was 10(-6)M, one log unit lower than in rat. These results suggest that the robust GSP response to Suc in rat and to QHCl in mouse likely do not depend upon a large number of taste cells expressing the taste receptors Tas1r2 for Suc or Tas2rs for QHCl, but upon a higher density of Tas1r2/Tas2rs within the respective taste cells of the two species.

The distribution of TRPV1 and TRPV2 in the rat pharynx.

Immunohistochemistry for two nociceptive transducers, the transient receptor potential cation channel subfamily V members 1 (TRPV1) and 2 (TRPV2), was performed on the pharynx and its adjacent regions. TRPV1-immunoreactivity (IR) was detected in nerve fibers beneath and within the epithelium and/or taste bud-like structure. In the pharynx, these nerve fibers were abundant in the naso-oral part and at the border region of naso-oral and laryngeal parts. They were also numerous on the laryngeal side of the epiglottis and in the soft palate. TRPV2-IR was expressed by dendritic cells in the pharynx and epiglottis, as well as in the root of the tongue and soft palate. These cells were located in the epithelium and lamina propria. TRPV2-immunoreactive (IR) dendritic cells were numerous in the naso-oral part of the pharynx, epiglottis, and tongue. Abundance of TRPV2-IR dendritic processes usually obscured the presence of TRPV2-IR nerve fibers in these portions. However, some TRPV2-IR nerve fibers could be observed in the epithelium of the soft palate. Retrograde tracing method also revealed that sensory neurons which innervate the pharynx or soft palate were abundant in the jugular-petrosal ganglion complex and relatively rare in the nodose ganglion. In the jugular-petrosal ganglion complex, TRPV1- and TRPV2-IR were expressed by one-third of pharyngeal and soft palate neurons. TRPV2-IR was also detected in 11.5 % pharyngeal and 30.9 % soft palate neurons in the complex. Coexpression of TRPV1 and CGRP was frequent among pharyngeal and soft palate neurons. The present study suggests that TRPV1- and TRPV2-IR jugular-petrosal neurons may be associated with the regulation of the swallowing reflex.

The distribution of transient receptor potential melastatin-8 in the rat soft palate, epiglottis, and pharynx.

Immunohistochemistry for transient receptor potential melastatin-8 (TRPM8), the cold and menthol receptor, was performed on the rat soft palate, epiglottis and pharynx. TRPM8-immunoreactive (IR) nerve fibers were located beneath the mucous epithelium, and occasionally penetrated the epithelium. These nerve fibers were abundant in the posterior portion of the soft palate and at the border region of naso-oral and laryngeal parts of the pharynx. The epiglottis was free from such nerve fibers. The double immunofluorescence method demonstrated that TRPM8-IR nerve fibers in the pharynx and soft palate were mostly devoid of calcitonin gene-related peptide-immunoreactivity (CGRP-IR). The retrograde tracing method also demonstrated that 30.1 and 8.7 % of sensory neurons in the jugular and petrosal ganglia innervating the pharynx contained TRPM8-IR, respectively. Among these neurons, the co-expression of TRPM8 and CGRP-IR was very rare. In the nodose ganglion, however, pharyngeal neurons were devoid of TRPM8-IR. Taste bud-like structures in the soft palate and pharynx contained 4-9 TRPM8-IR cells. In the epiglottis, the mucous epithelium on the laryngeal side had numerous TRPM8-IR cells. The present study suggests that TRPM8 can respond to cold stimulation when food and drinks pass through oral and pharyngeal cavities.

[Early morphogenesis of ciliated cells in human oral cavity].

Ciliated cells were found in the epithelium of the oral cavity of human embryos and fetuses starting from the seventh week of prenatal development. At the early stages of prenatal development (until the 13th week), cells with cilia cover most of the dorsal surface of the tongue and the soft palate, whereas they are found only near the gland ducts in the circumvallate and foliate lingual papillae after 17 weeks of development. The ultrastructure of the axoneme of cilia corresponds to the structure of motile cilia and is represented by nine microtubule doublets that surround the central pair of microtubule singlets. An immunohistochemical study performed on weeks 10-12 of development identified nerve endings associated with the ciliated cells. Until the 14th week of development, the cytoplasm of ciliated cells is immunopositive for NSE. The spatial distribution of ciliated cells in the tongue epithelium until the 13th week of development is not related to the morphogenesis of lingual papillae, and their role in the human oral cavity during the first trimester of pregnancy is unclear and requires further study.

Cell lineage mapping of taste bud cells and keratinocytes in the mouse tongue and soft palate.

The epithelium of the mouse tongue and soft palate consists of at least three distinct epithelial cell populations: basal cells, keratinized cells organized into filiform and fungiform papillae, and taste receptor cells present in tight clusters known as taste buds in the fungiform and circumvallate papillae and soft palate. All three cell types develop from the simple epithelium of the embryonic tongue and palate, and are continually replaced in the adult by cell turnover. Previous studies using pulse-chase tritiated thymidine labeling in the adult mouse provided evidence for a high rate of cell turnover in the keratinocytes (5-7 days) and taste buds (10 days). However, little is known about the localization and phenotype of the long-term stem or progenitor cells that give rise to the mature taste bud cells and surrounding keratinocytes in these gustatory tissues. Here, we make use of a tamoxifen-inducible K14-CreER transgene and the ROSA26 LacZ reporter allele to lineage trace the mature keratinocytes and taste bud cells of the early postnatal and adult mouse tongue and soft palate. Our results support the hypothesis that both the pore keratinocytes and receptor cells of the taste bud are derived from a common K14(+)K5(+)Trp63(+)Sox2(+) population of bipotential progenitor cells located outside the taste bud. The results are also compatible with models in which the keratinocytes of the filiform and fungiform papillae are derived from basal progenitor cells localized at the base of these structures.

Expression of gustducin overlaps with that of type III IP3 receptor in taste buds of the rat soft palate.

Type III IP3 receptor (IP3R3) is one of the common critical calcium-signaling molecules for sweet, umami, and bitter signal transduction in taste cells, and the total IP3R3-expressing cell population represents all cells mediating these taste modalities in the taste buds. Although gustducin, a taste cell-specific G-protein, is also involved in sweet, umami, and bitter signal transduction, the expression of gustducin is restricted to different subsets of IP3R3-expressing cells by location in the tongue. Based on the expression patterns of gustducin and taste receptors in the tongue, the function of gustducin has been implicated primarily in bitter taste in the circumvallate (CV) papillae and in sweet taste in the fungiform (FF) papillae. However, in the soft palate (SP), the expression pattern of gustducin remains unclear and little is known about its function. In the present paper, the expression patterns of gustducin and IP3R3 in taste buds of the SP and tongue papillae in the rat were examined by double-color whole-mount immunohistochemistry. Gustducin was expressed in almost all (96.7%) IP3R3-expressing cells in taste buds of the SP, whereas gustducin-positive cells were 42.4% and 60.1% of IP3R3-expressing cells in FF and CV, respectively. Our data suggest that gustducin is involved in signal transduction of all the tastes of sweet, umami, and bitter in the SP, in contrast to its limited function in the tongue.

Achados endoscópico e citológico das vias respiratórias de potros puro sangue inglês em início de treinamento no Jóquei Clube do Paraná / Respiratory endoscopic and cytological findings in english thoroughbred foals in the beginning of their training at Jóquei Clube do Paraná / Hallazgos endoscópicos y citológicos de las vias respiratorias de potros purasangre inglés a principio de entrenamiento en el jóquei clube do paraná

O sistema respiratório de dezesseis potros PSI, com dois anos, em início de treinamento no Jóquei Clube do Paraná, foi avaliado através da videoendoscopia e citologia do aspirado traqueobrônquico. Observou-se que em sete destes animais (43,75%) foi diagnosticada hiperplasia folicular linfóide de grau III (intenso) e, nos demais (56,25%), grau II (moderado). No momento do exame, houve deslocamento do palato mole de forma persistente em dois animais (12,5%) e de forma intermitente, em outros três (18,75%). Foi constatada epiglote com aspecto frágil em apenas um animal e observada hemiplegia laríngea (grau II) em outros dois casos. Ainda, constatou-se secreção traqueobrônquica em dez animais (62,5%), em sete dos quais (70%) foi realizado aspirado e exame citológico.

The respiratory system of sixteen 2-year-old thoroughbred foals in the beginning of their training at Jóquei Club do Paraná was evaluated through videoendoscopy and tracheobronchial cytology. Seven horses (43.75%) presented (severe) level III follicular hyperplasia, and the others (56.25%) level II (moderate). At the moment of the exam there was persistent soft palate displacements in two animals (12.5%), and intermittent in three (18.75%). The epiglottis was found to be fragile in only one animal, and the level II laryngeal hemiplegia was diagnosed in two other cases. Ten animals (62.5%) presented tracheobronchial secretion, and the aspirate and cytological exams were carried out in seven (70%).

Gene expression analysis reveals that formation of the mouse anterior secondary palate involves recruitment of cells from the posterior side.

Cleft palate is a common birth defect caused by disruptions in secondary palate development. Anterior-posterior (A-P) regional specification plays a critical role in palate development and fusion. Previous studies have shown that at the molecular level, the anterior palate can be defined by the expression of Shox-2 and the posterior palate by Meox-2 expression in certain mouse strains. Here, we have extended previous studies by performing a more detailed analysis of these genes during mouse palate development. We found that the expression patterns of Shox-2 and Meox-2 are dynamic during palate development. At embryonic day 12.5 (E12.5), Shox-2 expression is localized to the anterior end and its expression domain covers less than 25% of the length of the palate shelf. The Shox-2 expression domain then gradually expands towards the posterior end and ultimately occupies more than 60% of the palate shelf by E14.5. The expansion of the Shox-2 domain may involve induction of Shox2 expression in additional cells. Reciprocally, the Meox-2 expression domain at E12.5 covers a large portion of the palate shelf, a region more than 70% of the entire palate, but then regresses to the posterior 25% by E14.5. This regression is likely caused by the repression of Meox-2 expression in certain Meox2 expressing cells, rather than the cessation of cell proliferation. Therefore, certain Meox-2 positive "primitive posterior cells" are differentiated/converted into Shox-2 positive "definitive anterior cells" during A-P regional specification.

Immunohistochemical evaluation of metallothionein in palatal mucosal cells of mice treated with 4NQO.

OBJECTIVE: Metallothionein (MT) may play a preventive role in various carcinogenic process. 4NQO is an alkaline compound and potent mutagen that causes the formation of DNA adducts. The purpose of this study was to evaluate the immunoexpression of MT in palatal cells of mice submitted to the carcinogen 4NQO. STUDY DESIGN: C57BL/6 mice received applications of 4NQO to palate for periods of 8, 16, 20 and 24 weeks (experimental group). A control group received only applications of propylene glycol for the same periods. Subsequently animals of experimental and control groups were sacrificed and the palate was histologically analysed and MT immunohistochemistry performed. RESULTS: Although morphological atypical features were scant, the expression of MT was higher in the experimental group in comparison to controls. There was an amplified induction of MT expression in oral epithelium of mice treated by 4NQO. CONCLUSION: These results suggest that MT may act as an endogenous defensive factor against 4NQO in early phases of oral carcinogenesis.

Histology, immunohistochemistry and ultrastructure of the tonsil of the soft palate of the horse.

The tonsil of the soft palate was an oval, flat structure located centro-rostrally on the oral surface of the soft palate. Its stratified squamous non-keratinized epithelium was perforated by holes or small crypts the deeper parts of which were loosely spongiform inter-digitated with lymphoid tissue. These unusual features have not previously been reported in tonsils of any species. Crypts and reticulated epithelium as found in the lingual and palatine tonsils were not observed. Lectins showed varying affinities for specific layers of the epithelium. M cells were not observed. A few Langerhans cells were distributed among surface epithelial cells. Lymphoid tissue was arranged loosely and in isolated lymphoid follicles in the subepithelial lamina propria mucosae. Although IgA+ cells and macrophages were proportionately more numerous the amount of lymphoid tissue was much less than in the lingual and palatine tonsils. Most of the follicular germinal centres lacked a darkly stained corona. CD4 positive were more numerous than CD8+ lymphocytes and were distributed in the parafollicular and inter-follicular areas. Large clusters of mucus acini positive for glycogen, acidic and neutral mucopolysaccharides separated lymphoid tissue from deeply placed striated muscle. Only a few high endothelial venules were observed in the parafollicular and inter-follicular areas. These had relatively few vesiculo vacuolar or other organelles in their high endothelial cells and few lymphocytes attaching to their walls.