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Results for “budding”

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PubMed2004

[Stimulatory effects of low temperature treatment of germinating seeds on flower-bud differentiation in broccoli].

The effects of low temperature treatment (0-2 degrees C) of germinating seeds in accelerating process of flower-bud differentiation in broccoli (Brassica oleracea var. italica) were studied. The results indicated that low temperature treatment of germinating seeds for 10 d in broccoli (T(10)) lowered 0.86 nodes and advanced 5 d for the critical stage of flower-bud differentiation, stage of primary furcation scape primordium differentiation and stage of secondary and tertiary furcation scape primordium differentiation; Low temperature treatment of germinating seeds for 20 d in broccoli (T(20)) lowered 1.03 nodes and advanced 6 d for the critical stage of flower-bud differentiation , stage of primary furcation scape primordium differentiation and stage of secondary and tertiary furcation scape primordium differentiation. The node number at which flower-bud differentiation started under T(10) and T(20) was significantly lower than that of control while there was no significant difference between T(10) and T(20). In addition, the flower-bud differentiation was accompanied by increase in GA(3) contents, soluble protein contents, POD activities and invertase activities. GA(3) contents, soluble protein contents, POD activities and invertase activities started to increase significantly when plants entered the critical stage of flower-bud differentiation; POD activities, invertase activities and GA(3) contents emerge high apex value when plants entered stage of primary furcation scape primordium differentiation and stage of secondary and tertiary furcation scape primordium differentiation. Curve change trend of these physiological and biochemical indexes under T(10) and T(20) were accord with CK while advent of each high apex value was earlier about a week than CK during flower-bud differentiation. In a word, synthesization of GA(3) was induced firstly after germinating seeds were treated under low temperature, consequently POD activities and invertase activities were increased which took advantage of flower-bud differentiation.

Brassica↗

PubMed1992

A new interpretation of the necrotic changes occurring in the developing limb bud paddle of mouse embryos based upon recent observations in four different phenotypes.

Degenerative changes occurring in the apical ectodermal ridge (a.e.r.) and undifferentiated distal mesoderm of developing limb buds were studied macro- and microscopically in day-11 to day-13 mouse embryos displaying the normal (+/+), oligosyndactylous (Os/+), polydactylous (Xpl/+) and hybrid (Os/+/Xpl/+) phenotypes. Isolated limb buds were submitted either to supravital staining with Nile blue sulfate or to lectin binding staining in serial paraffin sections, taking advantage of strong binding affinites of macrophage cells for peanut agglutinin after neuraminidase treatment and for ricinus communis agglutinin. Necrotic changes detected in three definite areas of the distal mesoderm of normal limb buds exhibit characteristic spatial temporal relationships with earlier cytolytic changes affecting the pre- and postaxial parts of the a.e.r. Two of them, known as the primary preaxial site (fpp) and the anterior marginal necrotic zone (AMNZ) appeared deeply modified in mutant embryos as compared to the posterior marginal necrotic zone (PMNZ) which remained unaffected. Macrophage cells loaded with cell debris appear in advance and in excessive number in the fpp of Os/+ limb buds. Conversely, they were found absent or locally reduced in number in the fpp and AMNZ of Xpl/+ limb buds which otherwise develop in the same area a preaxial protrusion covered with a healthy portion of the a.e.r. Hybrid Os/+/Xpl/+ limb buds expressing both mutant genes develop a smaller and macrophage-free preaxial protrusion which coexists with residual and locally excessive necrotic changes in its immediate surrounding and is covered with a normally necrotic portion of the a.e.r. Microscopic observations collected in the limb buds of all phenotypes, though more frequently in Os/+ limb buds, strongly suggest that in all three necrotic sites examined, macrophage cells of vascular origin somehow contribute to the clearance of ectodermal necrotic debris and eventually return in the blood stream through the marginal vein and its affluents.

Animals↗

PubMed1985

Genetic analysis of developmental mechanisms in hydra. XVI. Effect of food on budding and developmental gradients in a mutant strain L4.

Effect of food was examined on the budding rate and the developmental gradients of a mutant hydra strain L4. This mutant strain has very high levels of head-inhibition potential gradient along its body axis (Takano & Sugiyama, 1983). It also has a reduced budding capacity when it is cultured using brine shrimp nauplii as food, but its budding capacity is significantly improved when a small amount of tubifex worm tissue is added to its diet of brine shrimp (Takano, 1984). To test whether or not this change of budding rate is correlated with the change in the levels of the head-activation or head-inhibition potential gradients, L4 animals were cultured on the diet of brine shrimp with or without addition of tubifex worm tissue and the budding rates and the gradient levels were examined in these animals. The results showed that food affected the budding rate in L4 without affecting its gradient levels. This suggests that the gradient levels and the budding rate in L4 are are uncorrelated to each other, and that therefore the high levels of head-inhibition potential are not the cause for the low budding rate in this strain (cf., Takano & Sugiyama, 1983).

Animals↗

PubMed1983

Morphology of taste buds on the gill arches of the mullet Mugil cephalus, and the killifish Fundulus heteroclitus.

The morphology of taste buds on the gill arches of two euryhaline teleosts, the mullet Mugil cephalus, and the killifish Fundulus heteroclitus, were investigated using light microscopic and scanning and transmission electron microscopic techniques. On the mullet gill arches, taste buds were limited to the pharyngeal surfaces of the smooth-surfaced gill rakers. On the killifish gill arches, taste buds were located on the pharyngeal surfaces of all gill rakers and on the gill arch itself at the bases of the gill rakers. Despite dramatic differences in gill-raker structure between these two species, the taste buds themselves were similar ultrastructurally and closely resembled those described in other fishes. Cells within the taste buds included spindle-shaped dark and light cells and basal cells. Ultrastructural features of both the light and dark cells could support either receptor or transport functions. Tufts of microvilli, including one thick microvillus per light cell and numerous thin microvilli per dark cell, protruded at the apex of each taste bud between the ridged surface epithelial cells. Light cells contained numerous tubular membrane elements some of which appeared to open onto the apical surface of the taste bud. Dark cells contained numerous microtubules and apical, electron-lucent vesicles possibly involved in transport.

Animals↗

PubMed1979

The distribution of alkaline phosphatase activity in normal and cross-species regenerated rat and mouse taste buds.

Alkaline phosphatase (ALK Pase) activity can be detected histochemically in the taste buds of rats but not mice. Since taste buds develop, regenerate and are maintained under the influence(s) of the sensory nerve it was decided to study cross-species regenerated buds of these two animals to determine whether the nerve also regulated ALK Pase development in taste cells. Grafts of rats sensory ganglion and mouse tongue or mouse ganglion and rat tongue were combined in the anterior chamber of the eyes of immunologically-deficient nude mice and the cross-species buds that developed at 35 days were examined histochemically for ALK Pase. The results revealed that the rat nerve did not cause ALK Pase to appear in any buds found in mouse tongue grafts and that mouse nerve could support buds containing ALK Pase in rat tongue tissue. Because the cross-species regenerated buds were histochemically characteristic of those normally found in rat or mouse tongue, there is no evidence that the foreign nerve altered gene expression for ALK Pase in the target organ, and the action of the nerve on gustatory epithelium appears to be that of activation and maintenance.

Alkaline Phosphatase↗

PubMed1979

Distribution of taste buds on fungiform and circumvallate papillae of bovine tongue.

The distribution of taste buds on the fungiform and circumvallate papillae of the cow tongue has been determined. The two tongues studied were from Holstein-Friesian cows four to six years of age; they contained 14,765 and 21,691 taste buds, respectively. The tip of the tongue is well supplied with fungiform papillae, and the posterior portion contains the circumvallate papillae. The midportion of the tongue contains relatively few taste papillae. The fungiform papillae contained 1,580 and 1,838 taste buds on the two tongues, respectively, and the circumvallate papillae were estimated to contain 13,185 and 19,853 taste buds. The highest concentration of taste buds therefore occurs in the circumvallate papillae; these relatively few papillae contain approximately 90% of the taste buds. On a circumvallate papilla, taste buds are found only on the papillary sidewall, with none either on the apical surface of the papilla or on the outer wall of the moat.

Animals↗

PubMed2003

Distribution of keratin 8-containing cell clusters in mouse embryonic tongue: evidence for a prepattern for taste bud development.

The initiation of the morphogenesis of gustatory papillae is independent of innervation. To address the question of whether taste bud formation is associated with gustatory papilla morphogenesis, we examined developing tongues in mouse embryos from embryonic day 11 to birth. Despite the smooth morphological appearance of the lingual dorsal surface at 13 days of gestation, we observed embryonic taste bud primordia as discrete collections of cytokeratin 8-positive and elongated cells in epithelial placodes in the anterior tongue. In subsequent stages until birth, cytokeratin 8 continues to be expressed in embryonic taste buds distributed in punctuate patterns at regular intervals along rows that are symmetrically located on both sides of the median sulcus in the dorsal anterior developing tongue. Embryonic taste buds were observed in the developing circumvallate papillae from 15.5 days of gestation until birth. The dorsal epithelium of the anterior tongue is not innervated when embryonic taste buds first occur. The increased numbers of embryonic taste buds in developing fungiform papillae until birth are not correlated with the neural invasion of the epithelium. Thus, taste buds occur prenatally more likely independently of the innervation.

Animals↗

PubMed1990

Transcellular labeling of taste bud cells by carbocyanine dye (DiI) applied to peripheral nerves in the barbels of the catfish, Ictalurus punctatus.

In order to study the pattern of innervation of taste buds and the surrounding epithelium, the carbocyanine dye diI was applied to the nerve stump in isolated, paraformaldehyde-fixed barbels obtained from channel catfish, Ictalurus punctatus. After a diffusion period of 7-41 days, the barbels were sectioned on a vibratome and examined with epifluorescence. Labeled axons were observed up to 1 cm from the site of application. Frequently, a fascicle of labeled axons turned outward toward the epithelium to innervate taste buds or to end apparently as free endings within the epithelium. Within 2-3 mm of the dye-application site, many taste buds contained one or at most 5-10, labeled spindle-shaped, presumed receptor, cells. In taste buds containing multiple labeled cells, the cells usually were arranged as intertwined pairs or triplets rather than being homogeneously distributed within the taste bud. In a few cases, labeled basal cells could be discerned among the labeled axons of the basal plexus. The cells of the taste bud apparently were labeled by transcellular passage of the dye from the nerve fibers into the cells. The limited number of labeled cells within each taste bud may indicate a special relationship between these cells and the nerve fibers innervating them.

Afferent Pathways↗

PubMed1993

Transcellular labeling by DiI demonstrates the glossopharyngeal innervation of taste buds in the lingual epithelium of the axolotl.

Innervation of the axolotl lingual epithelium by the glossopharyngeal nerve was examined to reveal its sensory target cells. The carbocyanine dye diI was applied to the nerve stump in the tongue fixed with paraformaldehyde. After a diffusion period of several months, the tongues were examined with a conventional epifluorescence microscope and a confocal laser scanning microscope (LSM) in wholemounts or preparations sectioned with a vibratome. Beneath the epithelium the labeled nerve fibers spread horizontally to form a meshwork of fibers, from which fascicles of fibers extended upward perpendicularly to the epithelium to innervate taste buds. Numerous taste buds were labeled by possible transcellular diffusion of diI. At the base of the taste bud, the nerve fibers branched and formed a basal plexus of fine fibers, on which numerous varicosities were seen. One or at most several taste cells were labeled in a taste bud. In the basal part of taste buds, the cell without an apical process, the basal cell, was also labeled. In the epithelium, between the taste buds, a few solitary cells were labeled. In some cases, a single fascicle of fibers innervating these cells was clearly shown by the LSM. In addition, fine fibers apparently formed free nerve endings in the epithelial cell layer. The results showed that the IX nerve innervated not only taste cells, but also presumed mechanosensory basal cells in the taste bud and the solitary cells of unknown function in the non-taste lingual epithelium. Afferent nerve responses to mechanical stimulation of the tongue may be explained by these non-taste cellular elements in the epithelium.

Ambystoma mexicanum↗

PubMed2005

Characteristics of initiation and early events for muscle development in the Xenopus limb bud.

In Xenopus laevis, limb buds start to develop at a later point of the larval stage, prior to metamorphosis. This onset of limb development in Xenopus is totally different from that in amniotes such as birds and mammals, in which limb buds emerge at an early stage of embryogenesis, in parallel with other organogenesis. We investigated limb myogenesis in Xenopus, focusing on myogenic gene expression, myogenic ability of limb bud cells in the early stage, and the origin of myogenic precursor cells in the limb bud. The Xenopus early limb bud contains myoD/cardiac actin-positive and pax3/pax7-negative cells. Interestingly, results of transplantation experiments have revealed that this early limb bud contains myogenic precursor cells. In order to know the contribution of myogenic cells in somites to myogenic precursor cells in the early limb bud, we used a Cre-LoxP system for tracing over a long period. The results of fate tracing for myogenic cells in somites of the Xenopus embryo suggested that early-specified myogenic cells in somites do not contribute to limb muscle in Xenopus. Taken together, the results suggest that limb muscle development in Xenopus has characteristics of initiation and early events distinct from those of other vertebrate clades.

Animals↗

PubMed1995

Effect of FGF on gene expression in chick limb bud cells in vivo and in vitro.

Fibroblast growth factors (FGFs) are central to signaling in the developing limb. FGF-2 and FGF-4 can substitute for the apical ectodermal ridge to maintain both limb bud outgrowth and polarizing region signaling. Here, we have repeated and extended previous studies and investigated local effects of the apical ectodermal ridge on gene expression of Msx-1, 5' members of the HoxD complex, and Bmp-2 in the limb bud mesenchyme and tested whether members of the FGF family can substitute for the ridge to maintain their expression patterns. We found that expression of Msx-1, Hoxd-13, and Bmp-2 in posterior limb bud mesenchyme is dependent on a local signal from the apical ectodermal ridge. When the apical ectodermal ridge of young chick wing buds is removed, or when posterior cells are taken from the bud and placed in culture, expression of Msx-1, Hoxd-13, and Bmp-2 is not detectable in posterior mesenchymal cells. Local application of FGF-soaked beads to posterior limb mesenchyme following ridge removal or addition of FGF to cultured cells maintains expression of Msx-1, Hoxd-13, and Bmp-2. In contrast, expression of Hoxd-11 in posterior mesenchyme appears to be stable in the absence of either the apical ectodermal ridge or FGF. Expression of Msx-1 in anterior and apical cells is also locally maintained by the apical ectodermal ridge and this effect can be reproduced by local application of FGF. Furthermore, the addition of FGF to cultured anterior limb bud cells maintains their ability to respond to positional cues when grafted back into limb buds.

Animals↗

PubMed1996

N-cadherin is involved in myoblast migration and muscle differentiation in the avian limb bud.

Limb muscle formation involves invasion of the limb bud mesoderm by myogenic precursor cells from the dermomyotomes at limb bud level. Directed cell migration, homing, and differentiation of myogenic cells are controlled by the stationary cells of the limb bud mesoderm. At the level of the extracellular matrix, the molecular basis of migration control has been suggested to be exerted by the distribution of hyaluronan. Here, we demonstrate that N-cadherin-mediated interactions play a role at cell-membrane level in myoblast distribution and differentiation. N-cadherin is strongly expressed by myogenic cells in the chick limb bud and more moderately expressed by stationary mesodermal cells in the myogenic zones and progress zone. After in vivo injection of antibodies and Fab-fragments against the homophilic binding site of N-cadherin into the wing bud mesoderm, aggregates of myoblasts are found predominantly in the dorsal myogenic zone 36 hr after injection apparently due to immobilization. In the same position, areas of myf-5-positive cells are also observed. In injected limb buds, Pax-3-positive cells are less evenly distributed than in uninjected limbs. They are found to spread up to the epidermis and also form loosely arranged aggregates. After prolonged reincubation periods, injected limbs show ectopic myoblasts that are rich in desmin and areas of strongly desmin-expressing myoblasts within muscle blastemas. These effects were not observed after application of antibodies against other parts of the N-cadherin molecule. We conclude that N-cadherin is involved in myoblast migration in the limb buds via homophilic interactions and that it plays a role in signal transduction during myogenesis.

Animals↗

PubMed2007

Immunohistochemical localization of aromatic L-amino acid decarboxylase in mouse taste buds and developing taste papillae.

Aromatic L-amino acid decarboxylase (AADC) catalyses the decarboxylation of all aromatic L-amino acids. In mammals, AADC is expressed in many tissues besides the nervous system, and is associated with additional regulatory roles of dopamine and serotonin in a wide range of tissues. We examined the expression of AADC by using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. RT-PCR analysis showed that mRNA of AADC was detected in the taste bud-containing epithelium of the circumvallate papilla of mice. By immunohistochemical analyses, AADC was detected in a subset of taste bud cells of fungiform, foliate, and circumvallate papillae. Double-label studies showed that AADC colocalized with serotonin, NCAM, PLCbeta2, and PGP9.5. On the other hand, AADC never colocalized with alpha-gustducin. Our results of double staining with AADC and taste cell markers indicate that only the type III cells could convert 5-hydroxytryptophan (5-HTP) to serotonin within taste buds. Taken together with previous studies, the properties of the type III cell of taste buds exactly fit into the APUD (amine and amine precursor uptake and decarboxylation) cell scheme. Furthermore, in the developing circumvallate papilla, AADC are first detected in a small number of papillary epithelial cells at E14.5. By E18.5, AADC-positive epithelial cells also express PGP9.5, which is one of marker of taste cells, and these cells have been contacted by developing nerve fibers. These results suggest that AADC expression begins at early stages of taste bud cell differentiation, and biogenic amines may act on taste bud differentiation of tongue epithelial cells, and further may regulate innervation of taste bud progenitor cells.

Animals↗

PubMed1985

Regeneration of taste buds by nongustatory nerve fibers.

Previous cross-reinnervation studies in situ by other investigators have demonstrated that cutaneous sensory and motor axons are incapable of trophically supporting mammalian taste buds. The present experiments examined the gustatory trophic potency of chemosensory and barosensory axons of the carotid sinus nerve. We report here that morphologically normal taste buds appeared on cat circumvallate papillae at 2 to 19 months after cross-anastomosis of the carotid sinus and lingual nerves, branches of the IXth cranial (glossopharyngeal) nerve. However, neurophysiologic and histologic data also indicated that, despite microsurgical procedures designed to direct regenerating lingual nerve fibers toward the carotid body and carotid sinus, some lingual axons escaped the anastomosis and subsequently grew within their native distal stump. The principal objective of this study was thus to determine whether foreign innervation of taste buds did indeed occur, or regenerated lingual nerve fibers were instead responsible for the newly formed buds. Our results showed that stray lingual fibers were not responsible for the reappearance of taste buds because transection of the original proximal lingual nerve stump (cross-anastomosed to the distal carotid sinus nerve stump) did not reduce the incidence of taste buds or the accumulation of radiolabeled material axoplasmically transported from the petrosal (sensory) ganglion. Autoradiography of labeled tissue samples showed that more than 90% of the taste buds were labeled at 8 and 9 days after lingual nerve transection. These data support the hypothesis that sensory axons in the carotid sinus nerve share an important trophic chemistry with gustatory neurons.

Animals↗

PubMed1980

Distribution of taste buds on the lips and inside the mouth in a minnow, Pseudorasbora parva.

The distribution and abundance of taste buds were quantitatively examined by observing silver impregnated serial sections. The taste buds were widely dispersed on the skin, the lips, the mucosa in the oro-pharyngeal cavity, the esophagus, and the branchial apparatus. The great majority of them was found on the lips and inside the mouth. The external buds were concentrated especially on the outer lips and the adjacent skin, while their number diminished in a caudal direction. Very few were found on the scaled skin. The total number of external buds in a specimen of 6 cm in length was 1,486. The number of taste buds inside the mouth was 6,600. On the inner lips and the palatal organ densities were found to reach over 140 per mm2. High concentrations of taste buds were also found on the gill arches and rakers. These taste buds varied to some extent in size and shape, depending on the thickness of the epithelial layer. It is suggested that the minnow may use the lips, gills and palatal organ as its main taste organs.

Animals↗

PubMed1979

The fine structural effect of sialectomy on the taste bud cells in the rat.

Taste buds in the rat and other mammals share a secretory activity with their transduction function as taste receptor. The present work shows the effect of bilateral removal of the main salivary glands on taste bud cells' components related to secretion in the vallate papilla of the rat. In the sialectomized rats remarkable changes were evidence in the dark and intermediate types of taste bud cells, which are known to be the secretory components. Such changes involve hypertrophy of either the protein synthetizing machinery, the smooth endoplasmic reticulum or the Golgi complex. Lucent and coated vesicles associated to Golgi cisternae increased in number but the amount of dense-core vesicles (secretory vesicles) at the apical cytoplasm of cells decreased. Images of exocytosis of secretory products were observed. The hypertrophy of Golgi complex components was clearly detected with the OsO4 impregnation method for light and electron microscopy. Alteration in the acid phosphatase activity of taste bud cells was not observed in the sialectomized rats. These findings suggest that sialectomy stimulates the entire secretory cycle of dark and intermediate taste bud cells. The light taste bud cells, which are not engaged in secretion, are hardly affected by the treatment. Although taste buds in mammals are neuro-dependent structures, present evidence indicates that they are also sensitive to non-neural influences.

Animals↗

PubMed2006

Effects of streptozotocin-induced diabetes on taste buds in rat vallate papillae.

Some studies have documented taste changes in patients with diabetes mellitus (DM). In order to understand the relationships between taste disorders caused by DM and the innervation and morphologic changes in the taste buds, we studied the vallate papillae and their taste buds in rats with DM. DM was induced in these rats with streptozotocin (STZ), which causes the death of beta cells of the pancreas. The rats were sacrificed and the vallate papillae were dissected for morphometric and quantitative immunohistochemical analyses. The innervations of the vallate papillae and taste buds in diabetic and control rats were detected using immunohistochemistry employing antibodies directed against protein gene product 9.5 (PGP 9.5) and calcitonin gene-related peptide (CGRP). The results showed that PGP 9.5- and CGRP-immunoreactive nerve fibers in the trench wall of diabetic vallate papillae, as well as taste cells in the taste buds, gradually decreased both intragemmally and intergemmally. The morphometry revealed no significant difference in papilla size between the control and diabetic groups, but there were fewer taste buds per papilla (per animal). The quantification of innervation in taste buds of the diabetic rats supported the visual assessment of immunohistochemical labeling, that the innervation of taste cells was significantly reduced in diabetic animals. These findings suggest that taste impairment in diabetic subjects may be caused by neuropathy defects and/or morphological changes in the taste buds.

Animals↗

PubMed1999

Expression of Mash1 in basal cells of rat circumvallate taste buds is dependent upon gustatory innervation.

Mash1, a mammalian homologue of the Drosophila achaete-scute proneural gene complex, plays an essential role in differentiation of subsets of peripheral neurons. In this study, using RT-PCR and in situ RT-PCR, we investigated if Mash1 gene expression occurs in rat taste buds. Further, we examined dynamics of Mash1 expression in the process of degeneration and regeneration in denervated rat taste buds. In rat tongue epithelium, Mash1 gene expression is confined to circumvallate, foliate, and fungiform papilla epithelia that include taste buds. In taste buds, Mash1-expressing cells are round cells in the basal compartment. In contrast, the mature taste bud cells do not express the Mash1 gene. Denervation and regeneration experiments show that the expression of Mash1 requires gustatory innervation. We conclude that Mash1 is expressed in cells of the taste bud lineage, and that the expression of Mash1 in rat taste buds is dependent upon gustatory innervation.

Animals↗