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PubMedDate not supplied

Activity of cathepsin B and D in colorectal cancer: relationships with tumour budding.

UNLABELLED: It has been reported that poorly-differentiated clusters of cancer cells at the invasive front, namely "tumour budding", may reflect malignancy of colorectal cancer. The aim of the present study was to evaluate the activity of cathepsin D and B in tumours and in normal mucosa from pT3 and G2 colorectal cancers, and to analyse their association with tumour budding at the invasion front of colorectal cancer. PATIENTS AND METHODS: A total of 40 patients classified as pT3, G2 underwent curative resection of colon cancer between 1997 and 2001. The fragments of tumours and normal colorectal tissue were obtained for biochemical examinations. We also categorized tumour budding (TB) at the front of invasion. Two groups were used for classification of the TB phenomenon: the first where no bud was observed- TB(-), and the second where at least one bud was found -TB(+) at the front of invasion in the examined slice. RESULTS: The activity of cathepsins D and B was found to be statistically significantly higher both in the neoplastic tissue cytosol and homogenate, compared to the cytosol and homogenate of adjacent healthy tissue (p<0.05). There was, however, no significant difference between tumour budding and the activity of cathepsin D in tumour tissue, but we found a statistically significant difference between the activity of cathepsin B in the homogenate and cytosol of tumour tissue and budding-positive tumours (p=0.027, p=0.004, respectively). CONCLUSION: These results suggest that the activity of cathepsin D is not involved in tumour budding. In our opinion, much more attention should be paid to cathepsin B, as a potentially responsible factor in tumour progression, since it strongly increased with the presence of tumour budding.

Adult↗

PubMed1975

[Demonstration, by means of electron microscopy, of the penetration of somitic cells into the mesoblast of the limb buds of reptile embryos (Anguis fragilis, Lacerta viridis)].

An electron microscopic study of the components of anterior limb buds of the slow-worm (Anguis fragilis) and of the green lizard (Lacerta viridis) (embryos of Anguis whose allantoic bud reach 0,7 to 4 mm of length; embryos of Lacerta 2 to 7 days old) provides data on the cytological characteristics of the components of the limb bud at these early stages. 1. The cells of the distal extremity of the somitic processes extending in the limb bud of Anguis and Lacerta, are elongated cells with ovoid nuclei containing large nucleolus; they possess mitochondria always thin and with dense matrix; they are rich in lipid droplets; they possess cilia; they are devoid of myofilaments; endoplasmic reticulum, free ribosomes and polyribosomes are abundant. Golgi networks display signs of activity. These characteristics are also observed in the cells of the "dermatome" layer of the dermo-myotome; and so, it appears probable that the cells of the "dermatome". Furthermore, in Anguis embryos, the cells of the distal extremities of the somitic processes possess numerous lysosomes and a certain number of cells among them, degenerate early. 2. The somatopleural mesoblastic cells of the limb bud of Anguis and Lacerta embryos keep the characters of the cells of the mesodermic layer of lateral plate from which they originate; they have rounded nuclei, cilia, and their mitochondria are always larger and more transparent to electrons, than the ones of cells of the somitic processes and of cells of the epiblastic apical crest. Golgi networks are well developped, endoplasmic reticulum is abundant, lipid droplets are rare. 3. The processes of somites which extend in the dorsal part of the limb bud of Anguis embryos are cords of cells with thin lumina; at the stage of the allantoic bud of 0,6 to 0,8 mm long, the distal extremity of these processes dislocate in group of cells which afterwards dissociate, releasing individual somitic cells which are integrated among the mesoblastic somatopleural cells. In young lizard embryos (2 to 4 days old) the distal extremity of the somitic processes enlarges into a vesicle from which cells are released and penetrate in the mesoblast of the limb bud. 4. The somitic cells released from the somitic processes of Anguis and Lacerta keep--at least at early stages--the cytological characteristics they displayed when they were still in situ in the somitic processes: grounded on the presence or absence of lipid droplets, on the width and density of the mitochondria, the distinction, at these stages, between the somitic and mesoblastic somatoplerual cells is possible; and it is also possible to observe the integration of the somitic cells into the mesoblast. This study brings the demonstration of the cellular contribution of the somites to the formation of the limb bud in Reptiles. 5...

Allantois↗

PubMed1999

Cellular expression of alpha-gustducin and the A blood group antigen in rat fungiform taste buds cross-reinnervated by the IXth nerve.

Although taste buds are trophically dependent on their innervation, cross-reinnervation experiments have shown that their gustatory sensitivities are determined by the local epithelium. Both the gustatory G-protein, alpha-gustducin, and the cell-surface carbohydrate, the A blood group antigen, are expressed by significantly fewer fungiform than vallate taste cells in the rat. In these experiments, one side of the anterior portion of the tongue was cross-reinnervated by the IXth nerve in order to determine whether the molecular expression of taste bud cells is determined by the epithelium from which they arise or by the nerve on which they are trophically dependent. The proximal portion of the IXth nerve was anastomosed to the distal portion of the chorda tympani (CT) nerve using fibrin glue (IX-CT rats). Control animals had the CT cut and reanastomosed using the same technique (CT-CT rats), or had the CT avulsed from the bulla and resected to prevent regeneration (CTX rats). The animals survived for 12 weeks postoperatively, and the tongues were removed, stained with methylene blue, and the fungiform taste pores counted on both sides. Tissue from the anterior 5 mm of the tongue was cut into 50-microm sections, which were incubated with antibodies against alpha-gustducin and the human blood group A antigen. In both CT-CT and IX-CT rats, there was regeneration of fungiform taste buds, although in both groups there were significantly fewer taste buds on the operated side of the tongue. The normal vallate papilla had a mean of 8.37 alpha-gustducin-expressing cells and 5.22 A-expressing cells per taste bud, whereas the fungiform papillae contained 3.06 and 0.23 cells per taste bud, respectively. In both CT-CT and IX-CT rats there was a normal number of cells expressing alpha-gustducin or the A antigen in regenerated taste buds; in the CTX animals there was a significant decrease in the expression of these markers. These results demonstrate that the molecular phenotype of taste bud cells is determined by the local epithelium from which they arise and not by properties of the innervating nerve.

ABO Blood-Group System↗

PubMed1998

Hox gene expression, AV-1 antigen expression, and cartilage pattern formation in chick recombinant limb buds.

A recombinant limb bud composed of dissociated and reaggregated mesenchyme and an ectodermal jacket develops a limblike structure with bifurcated and segmented cartilage. We compared the cartilage structure formed from recombinants that were composed of mesenchymal cells derived from the limb bud progress zone at various stages. In the case of recombinants containing distal mesenchyme of early-stage limb buds (stage 18 or 20), long and thick cartilage structures were formed in the proximal region, and segmented digitlike structures were formed in the distal region. On the contrary, in the case of recombinants containing distal mesenchyme of late-stage limb buds (stage 25 or 27), only poorly developed cartilage structures were formed. Next, we analyzed expression patterns of the position-specific genes HoxA11, A13 and D12 and the position-specific antigen AV-1 protein in recombinants containing distal mesenchyme of stage 20 limb buds (stage 20 recombinants) or stage 25 limb buds (stage 25 recombinants). In stage 20 recombinants, HoxA11 was expressed throughout the mesenchyme, but HoxA13 was expressed only in the distal half of the mesenchyme. In stage 25 recombinants, HoxA13 was expressed throughout the mesenchyme, but HoxA11 was only faintly expressed. The expression pattern of HoxD12 was similar to that of HoxA13 in both stage 20 and stage 25 recombinants, and no asymmetric expression pattern, which is observed in normal limb buds, was detected. AV-1 antigen was expressed in the core region of stage 20 recombinants, and anteroposterior asymmetry, which is observed in the anterior-ventral-distal region of normal limb buds, was not found. No AV-1 expression was observed in stage 25 recombinants. These results suggest that the mesenchyme in recombinants shows spatially controlled gene/protein expressions along the proximodistal axis, and that these differences in gene/protein expressions may affect cartilage pattern formation in recombinants.

Animals↗

PubMed1985

Age does not affect numbers of taste buds and papillae in adult rhesus monkeys.

Taste buds and papillae in tongues of rhesus monkeys were examined and counted to determine if there are age-related differences in general morphology or numbers of receptor organs. Tongues from 15 monkeys in five groups aged 4-31 years were studied with light microscopy. Fungiform, circumvallate, and foliate papillae were examined and taste buds in each papilla type were counted. Numbers of papillae did not differ with age through 31 years; however, at 24 years and older, fungiform papillae were reduced in number in some animals that had lost tongue tips due to trauma. There were no age-related differences in numbers of taste buds in any of the three gustatory papilla types, nor did taste bud diameter alter with age. From data on each papilla type, estimates were made of total numbers of lingual taste buds. Totals ranged from about 8,000 to 10,000 and there were no age-related differences. These results support other recent reports that taste buds are not decreased in number in old rats or humans. Since taste bud numbers and general morphology are maintained even in old age, any age-related differences in taste behavior cannot be attributed to gross degenerative changes in lingual taste buds.

Aging↗

PubMed2005

Effects of glossopharyngeal nerve section on the expression of neurotrophins and their receptors in lingual taste buds of adult mice.

The expression of neurotrophins and neurotrophin receptors is essential for the proper establishment and function of many sensory systems. To determine which neurotrophins and neurotrophin receptors are expressed in taste buds, and in taste buds of mice following denervation, antibodies directed against the neurotrophins and their receptors were applied to adult mouse gustatory tissue. Immunohistochemistry reveals that nerve growth factor (NGF)-like immunoreactive (LIR), tyrosine kinase (trk) A-LIR, trkB-LIR, and p75-LIR elongated, differentiated taste cells are present within all lingual taste buds, whereas neither neurotrophin (NT)-3- nor trkC-LIR was detected in taste cells. Double-label immunohistochemistry using markers of different taste cell types in brain-derived neurotrophic factor (BDNF)LacZ mice reveals that BDNF (beta-gal) and trkB colocalize, mainly in type III taste cells. NGF, pro-NGF, and trkA coexist in type II taste cells, i.e., those expressing phospholipase Cbeta2 (PLCbeta2). p75-LIR also is present in both BDNF and NGF taste cell populations. To determine the neural dependence of neurotrophin expression in adult taste buds, glossopharyngeal nerves were cut unilaterally. During the period of denervation (10 days to 3 weeks), taste buds largely disappear, and few neurotrophin-expressing cells are present. Three weeks after nerve transection, nerve fascicles on the operated side of the tongue exhibit BDNF-LIR, NGF-LIR, and ubiquitin carboxyl terminal hydrolase (PGP 9.5)-LIR. However, BDNF-LIR staining intensity but not NGF-LIR or PGP 9.5-LIR is increased in nerve fascicles on the operated compared with the unoperated side. Five weeks following nerve transection, NT and NT receptor expression resumes and appears normal in taste buds and nerves. These results indicate that neurotrophin expression in taste buds is dependent on gustatory innervation, but expression in nerves is not dependent on contact with taste buds.

Animals↗

PubMed1977

Regeneration of fungiform taste buds: temporal and spatial characteristics.

The gross morphology of the tongue of the Mongolian gerbil Meriones unguiculatus), the location of papillae and taste buds, and the normal innervation pattern of the tongue and taste buds were determined. The chorda tympani nerve was interrupted to produce degeneration of fungiform taste buds. Regenerating chorda tympani axons followed the original nerve pathways in the tongue en route to the fungiform papillae in the epithelium where they initiated the regeneration of taste buds. The spatial distribution of reinnervated fungiform papillae and reformed taste buds was examined 7 to 19 days following surgery. Beginning at eight days following chorda tympani interruption there was a progressive increase, first, in the proportion of fungiform papillae that were reinnervated, and later in the number of reformed taste buds. On the basis of these measures it was concluded that a taste bud is reformed one to two days after reinnervation of its papilla. From the time course of reinnervation of the fungiform papillae it was calculated that some fibers regenerated at rates in excess of 2 mm/day. Regeneration was precise and systematic. The regenerating chorda tympani fibers accurately returned to the fungiform papillae; they did not follow the pathways of lingual nerve axons. In the initial stages of recovery both reinnervated papillae and reformed taste buds were preferentially located toward the front of the tongue; the reinnervation of posterior fungiform papillae was delayed.

Animals↗

PubMed1981

Regeneration of taste buds after reinnervation of a denervated tongue papilla by a normally nongustatory nerve.

Taste buds degenerate and disappear after transection of their sensory nerve supply, and they differentiate anew from epithelial cells (e.g., lingual) following regeneration of sensory but not motor or autonomic axons. A controversy exists as to whether only gustatory sensory nerves can cause buds to reform or whether any sensory nerve can perform this function. This issue arose because the results of cross-innervation studies revealed a specificity whereas grafting data demonstrated a nonspecificity. A retest of specificity in the cross-reinnervation situation was performed by reinnervating the denervated vallate papilla of adult rat tongue with a sensory branch of the vagus nerve that is not normally gustatory. It was found that taste buds disappeared and remained lost from acutely and chronically denervated papilla. However, some buds were found 90-100 days after reinnervation by the normally nongustatory vagus nerve branch. Transection of the regenerated vagus nerve resulted in the loss of innervation and the degeneration of taste buds from reinnervated papilla indicating that this nerve had supported buds. These results show that a normally nongustatory nerve can induce the formation of taste buds after its axons grow into appropriate tissue. It appears that the ability to support taste buds is a nonspecific, rather than a specific, property of sensory nerve.

Animals↗

PubMed1991

Immunocytochemistry of gamma-aminobutyric acid, glutamate, serotonin, and histamine in Necturus taste buds.

Little information is currently available about which neurotransmitters are involved in signal processing in the peripheral sensory organs of taste, taste buds. Synaptic contacts between taste cells and sensory axons have long been known to exist, but what substances are active at these synapses is not known. Our objective in this study was to test for the presence of the neurotransmitter candidates, GABA, glutamate, serotonin, and histamine in taste buds of Necturus maculosus. Light microscopic immunocytochemical techniques were used to investigate the location of these substances in taste buds and surrounding epithelium. GABA and glutamate were detected in nerve fibers that innervate the taste buds, and, to a substantially lesser extent, in fine, varicose axons that penetrated the surrounding nontaste epithelium. Serotonin immunostaining was strong in basal cells in frog taste discs but was only faintly detected in Necturus taste buds. Histamine was not detected at all in taste buds. We conclude that amino acid neurotransmission may be involved in taste mechanisms and that monoamines may also play a role in chemosensory transduction in the taste bud. On the basis of our inability to detect histamine with immunocytochemical techniques, we conclude that this substance is unlikely to be a major neurotransmitter in Necturus taste buds.

Animals↗

PubMed1993

Aspects of vertebrate gustatory phylogeny: morphology and turnover of chick taste bud cells.

The taste bud is a receptor form observed across vertebrates. The present report compares chick taste buds to those of other vertebrates using light and electron microscopy. Unlike mammals, but common to many modern avians, the dorsal surface of chick anterior tongue lacks taste papillae and taste buds. Ultrastructurally, chick buds located in the anterior floor of the mouth (as in some reptiles and amphibians) and palate contain dark, intermediate, light, and basal cell types. Dark, intermediate, and light cells extend microvilli into intragemmal lumina and pores communicating with the oral cavity. As specialized features, dark cell apices lack dense granules and exhibit short microvilli relative to light and intermediate cells. Dark cell cytoplasmic fingers envelop intragemmal nerve fibers and cells as in other species, and sometimes contain abundant clear vesicles. Nerve profile expansions often are located adjacent to dark, intermediate, and light cell nuclei. Classical afferent synaptic contacts are rarely observed. Taste cell turnover is suggested by mitotic and degenerating figures in chick buds. In addition, tritiated thymidine injected into hatchlings, whose anterior mandibular oral taste bud population approximates that in adults, reveals a turnover rate of about 4.5 days. This is about half that observed in altricial mammals, reflecting a species difference or developmental factor in precocial avians. It is concluded that chick taste buds exhibit morphologic features common to other vertebrate buds with specializations reflecting the influences of niche, glandular relations, and/or age.

Animals↗

PubMed1995

Embryonic origin of amphibian taste buds.

Despite numerous descriptive studies, the embryonic origin of vertebrate taste buds has never been experimentally determined. A number of different alternatives have been suggested for taste bud origins, including epibranchial placodes, the neural crest, and the local epithelium of the oropharyngeal cavity. The role of a series of epibranchial placodes and the cephalic neural crest, which together give rise to the cranial nerves innervating taste buds, was examined with regard to the development of oropharyngeal taste buds in an ambystomatid salamander, the axolotl. When pigmented placodal ectoderm or neural folds were grafted isotopically and isochronically into nonpigmented host embryos, known derivatives of each tissue contained pigmented cells, but labeled taste buds were never encountered. Thus, neither epibranchial placodes nor neural crest contribute cells to taste buds during embryogenesis. The majority of the oropharyngeal cavity of ambystomatid salamanders is lined by an endodermal epithelium. In order to demonstrate conclusively that taste buds arise from this local epithelium, the presumptive cephalic endoderm of early axolotl gastrulae was microinjected with the lipophilic dye, DiI. In the oropharyngeal epithelium of all larvae examined, both taste buds and general epithelial cells were labeled with DiI, indicating their common endodermal origin. Our findings are novel in that this is the first experimental demonstration of the endodermal origin of a vertebrate sensory receptor cell class.

Ambystoma↗

PubMed2006

The effect of beta-bungarotoxin, or geniculate ganglion lesion on taste bud development in the chick embryo.

Chick taste bud (gemmal) primordia normally appear on embryonic day (E) 16 and incipient immature, spherical-shaped buds at E17. In ovo injection of beta-bungarotoxin at E12 resulted in a complete absence of taste buds in lower beak and palatal epithelium at developmental ages E17 and E21. However, putative gemmal primordia (solitary clear cells; small, cell groupings) remained, lying adjacent to salivary gland duct openings as seen in normal chick gemmal development. Oral epithelium was immunonegative to neural cell adhesion molecule (NCAM) suggesting gemmal primordia are nerve-independent. Some NCAM immunoreactivity was evident in autonomic ganglion-like cells and nerve fibers in connective tissue. After unilateral geniculate ganglion/otocyst excision on E2.5, at developmental ages E18 and posthatching day 1, approximately 12% of surviving ipsilateral geniculate ganglion cells sustained approximately 54% of the unoperated gemmal counts. After E18, proportional stages of differentiation in surviving developing buds probably reflect their degree of innervation, as well as rate of differentiation. Irrespective of the degree of geniculate ganglion damage, the proportion of surviving buds can be sustained at the same differentiated bud stage as on the unoperated side, or may differentiate to a later bud stage, consistent with the thesis that bud maturation, maintenance, and survival are nerve-dependent.

Animals↗

PubMed1996

Apoptosis in mouse taste buds after denervation.

Apoptotic cells in the taste buds of mouse circumvallate papillae after the sectioning of bilateral glossopharyngeal nerves were examined by the method of DNA nick-end labeling (TUNEL), together with standard electron microscopy. The taste buds decreased in number and size 3-11 days after denervation and disappeared at 11 days. The TUNEL method revealed only a few positively stained nuclei in normal taste buds but, in those of mice 1-5 days after denervation, the number of positive nuclei had increased to 3-5 times that of taste buds from normal mice. Electron-microscopic observation after denervation demonstrated taste bud cells containing condensed and fragmentary nuclei in a cytoplasm with increased density. The results show that taste bud cells under normal conditions die by apoptosis at the end of their life span, and that gustatory nerve sectioning causes apoptosis of taste bud cells with taste buds decreasing in number and ultimately disappearing.

Animals↗

PubMed1985

Number and distribution of taste buds in the oral cavity of hatchling chicks.

The location and number of taste buds were mapped in palatal epithelia of one-day old chicks and bud widths measured. Bud counts additionally were recorded for the tongue, and floor of the lower beak. An average of 316 taste buds was observed in the oral cavity of which 69%, 29% and 2% were distributed across oral epithelium in the upper beak (palate), lower beak and posteroventrolateral region of the anterior tongue, respectively. In each oral region, salivary gland ducts lying adjacent as well as gland ductules penetrating through the buds were prevalent. This relation may provide the bio-fluid milieu for receptor stimulation during feeding. Widths of palatal buds were bimodally distributed, peaking at diameters between 40-49 and 60-69 microns. The taste bud-rich oral epithelium in these one-day old chicks is consonant with their precocial nature. The topographic distribution of taste buds appears to be in register with those regions of epithelium contacted by food which is transported anteroposteriorly through the oral cavity by the chicken's prehensile tongue.

Age Factors↗

PubMed2006

Misexpression of Sox9 in mouse limb bud mesenchyme induces polydactyly and rescues hypodactyly mice.

Our previous studies have demonstrated the essential roles of the transcription factor Sox9 in the commitment of mesenchymal cells to a chondrogenic cell lineage and in overt chondrogenesis during limb bud development. However, it remains unknown if Sox9 induces chondrogenesis in mesenchyme ectopically in vivo as a master regulator of chondrogenesis. In this study, we first generated mutant mice in which Sox9 was misexpressed in the limb bud mesenchyme. The mutant mouse embryos exhibited polydactyly in limb buds in association with ectopic expression of Sox5 and Sox6 although markers for the different axes of limb bud development showed a normal pattern of expression. Misexpression of Sox9 stimulated cell proliferation in limb bud mesenchyme, suggesting that Sox9 has a role in recruiting mesenchymal cells to mesenchymal condensation. Second, despite the facts that misexpression of Sonic hedgehog (Shh) induces polydactyly in a number of mutant mice and Shh-null mutants have severely defective cartilage elements in limb buds, misexpression of Sox9 did not restore limb bud phenotypes in Shh-null mutants. Rather, there was no expression of Sox9 in digit I of Hoxa13Hd mutant embryos, and Sox9 partially rescued hypodactyly in Hoxa13Hd mutant embryos. These results provide evidence that Sox9 induces ectopic chondrogenesis in mesenchymal cells and strongly suggest that its expression may be regulated by Hox genes during limb bud development.

Animals↗

PubMed2003

Patterning of forelimb bud myogenic precursor cells requires retinoic acid signaling initiated by Raldh2.

Limb skeletal muscle is derived from cells of the dermomyotome that detach and migrate into the limb buds to form separate dorsal and ventral myogenic precursor domains. Myogenic precursor cell migration is dependent on limb bud mesenchymal expression of hepatocyte growth factor/scatter factor (Hgf), which encodes a secreted ligand that signals to dermomyotome through the membrane receptor tyrosine kinase Met. Here, we find that correct patterning of Hgf expression in forelimb buds is dependent on retinoic acid (RA) synthesized by retinaldehyde dehydrogenase 2 (Raldh2) expressed proximally. Raldh2(-/-) forelimb buds lack RA and display an anteroproximal shift in expression of Hgf such that its normally separate dorsal and ventral expression domains are joined into a single anterior-proximal domain. Met and MyoD are expressed in this abnormal domain, indicating that myogenic cell migration and differentiation are occurring in the absence of RA, but in an abnormal location. An RA-reporter transgene revealed that RA signaling in the forelimb bud normally exists in a gradient across the proximodistal axis, but uniformly across the anteroposterior axis, with all proximal limb bud cells exhibiting activity. Expression of Bmp4, an inhibitor of Hgf expression, is increased and shifted anteroproximally in Raldh2(-/-) limb buds, thus encroaching into the normal expression domain of Hgf. Our studies suggest that RA signaling provides proximodistal information for limb buds that counterbalances Bmp signaling, which in turn helps mediate proximodistal and anteroposterior patterning of Hgf expression to correctly direct migration of Met-expressing myogenic precursor cells.

Aldehyde Oxidoreductases↗

PubMed2001

Expression of cyclin-dependent kinase inhibitors in taste buds of mouse and hamster.

Taste buds are specialized epithelial cell clusters in the oral squamous cell epithelium. Although taste buds have been reported to renew rapidly, the mechanism of cell cycle control in these specialized structures remains unresolved. To clarify the cell cycle status and role of cyclin-dependent kinase inhibitors (CDKI) for cell cycle control in the taste buds, we analyzed cell proliferation activity using bromodeoxyuridine (BrdU) and Ki-67 immunostainings and the expression of the Cip/Kip family of CDKI (p21Cip1, p27Kip1, and p57Kip2) in the circumvallate papillae of mouse and hamster. BrdU-positive cells were detected in the basal layer of the oral epithelium. In the taste buds, Ki-67-positive cells were seen in the basal area, with only a very few positive cells in the taste buds. Both p21Cip1 and p27Kip1 positive cells were seen in the suprabasal layer of the non-gustatory oral epithelium. In the taste buds, stronger p27Kip1 staining was detected than in the non-gustatory epithelium. Western blotting analysis revealed that p27Kip1 was abundant in the mucosal tissues from circumvallate papillae. Thus, our study suggests that the taste bud cells except for basal cells are post-mitotic cells and that the cell cycle arrest associated with taste bud cell differentiation could be regulated predominantly by p27Kip1.

Animals↗

PubMed2001

Maintenance of rat taste buds in primary culture.

The differentiated taste bud is a complex end organ consisting of multiple cell types with various morphological, immunocytochemical and electrophysiological characteristics. Individual taste cells have a limited lifespan and are regularly replaced by a proliferative basal cell population. The specific factors contributing to the maintenance of a differentiated taste bud are largely unknown. Supporting isolated taste buds in culture would allow controlled investigation of factors relevant to taste bud survival. Here we describe the culture and maintenance of isolated rat taste buds at room temperature and at 37 degrees C. Differentiated taste buds can be sustained for up to 14 days at room temperature and for 3-4 days at 37 degrees C. Over these periods individual cells within the cultured buds maintain an elongated morphology. Further, the taste cells remain electrically excitable and retain various proteins indicative of a differentiated phenotype. Despite the apparent health of differentiated taste cells, cell division occurs for only a short period following plating, suggesting that proliferating cells in the taste bud are quickly affected by isolation and culture.

Animals↗