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排序方式: 共有711条查询结果,搜索用时 15 毫秒
91.
Vivien Jane Coulson-Thomas Tarsis Ferreira Gesteira Jeffrey Esko Winston Kao 《The Journal of biological chemistry》2014,289(36):25211-25226
Hair follicle (HF) morphogenesis and cycling are a result of intricate autonomous epithelial-mesenchymal interactions. Once the first HF cycle is complete it repeatedly undergoes cyclic transformations. Heparan sulfate (HS) proteoglycans are found on the cell surface and in the extracellular matrix where they influence a variety of biological processes by interacting with physiologically important proteins, such as growth factors. Inhibition of heparanase (an HS endoglycosidase) in in vitro cultured HFs has been shown to induce a catagen-like process. Therefore, this study aimed to elucidate the precise role of HS in HF morphogenesis and cycling. An inducible tetratransgenic mouse model was generated to excise exostosin glycosyltransferase 1 (Ext1) in keratin 14-positive cells from P21. Interestingly, EXT1StEpiΔ/StEpiΔ mice presented solely anagen HFs. Moreover, waxing the fur to synchronize the HFs revealed accelerated hair regrowth in the EXT1StEpiΔ/StEpiΔ mice and hindered cycling into catagen. The ablation of HS in the interfollicular epidermal cells of mature skin led to the spontaneous formation of new HFs and an increase in Sonic Hedgehog expression resembling wild-type mice at P0, thereby indicating that the HS/Sonic Hedgehog signaling pathway regulates HF formation during embryogenesis and prevents HF formation in mature skin. Finally, the knock-out of HS also led to the morphogenesis and hyperplasia of sebaceous glands and sweat glands in mature mice, leading to exacerbated sebum production and accumulation on the skin surface. Therefore, our findings clearly show that an intricate control of HS levels is required for HF, sebaceous gland, and sweat gland morphogenesis and HF cycling. 相似文献
92.
Abstract. Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis De Geer (Diptera: Gasterophilidae) and Oestrus ovis (L.) were studied by scanning electron microscopy. Two types of trichoid sensilla, two types of coeloconic sensilla and a pit sensillum were present on the thoracic and abdominal segments of G. intestinalis larvae. Sensilla on larvae of O. ovis were similar although only one type of trichoid sensillum was present. Total number of sensilla were higher for O. ovis than for G. intestinalis (248 v . 214). Variation in numbers of sensilla is consistent with the concept that increasing numbers of sensilla are associated with increasingly complex searching behaviour required to locate suitable habitats for development. 相似文献
93.
94.
The topography of long hair sensilla on the coxae of walking legs and pedipalps of the scorpionHeterometrus fulvipes is described. Identified long hair sensilla are cobalt filled, and central projections of sensory fibres are reported for
the first time in the suboesophageal ganglion of this scorpion. The afferent fibres arising from each long hair sensilla segregate
into ventral, dorsomedial and dorsal tracts upon their entry into the suboesophageal ganglion. These transverse tracts bifurcate
towards the middle of the leg neuromere and form three ipsilateral, plurisegrnental, longitudinal sensory pathways. Filling
a pair of bilaterally distributed long hair sensilla shows bilaterally arranged longitudinal afferent tracts interconnected
by distinct transverse commissures. Similar patterns of sensory projections are observed when filling homologous hairs on
other legs and pedipalps. Numerous fine collaterals arise from the longitudinal sensory trancts that subdivide and end in
small blebs presumed to be presynaptic endings. The dorsal and dorsomedial longitudinal tracts and their respective commissures
are in close association with the dendritic arborisations of pedipalpal and leg motor neurons, suggesting direct contact between
them. The probable functions of these multisegmental hair afferent pathways are discussed. 相似文献
95.
One pair of gustatory sensilla was found on the epipharynx ofBombyx mori larvae, and some morphological and electrophysiological characteristics of the epipharyngeal sensilla were investigated.
They are sensilla coeloconica composed of a small papilla with a pore at the tip and a swelling of cuticle encircling the
papilla. Three bipolar neurons innervate each sensillum. One neuron is an inositol receptor which responds to inositol only.
Another cell responds with action potentials of relatively large amplitude to some feeding deterrent substances, such as strychnine
nitrate. The thresholds of these cells for inositol and strychnine nitrate are approximately 10−4 M and 10−7 M, respectively. At least two kinds of spikes can be observed when these sensilla are stimulated with some salts and acids.
Dose-response relationships and time courses of responses to inositol and strychnine nitrate were also examined in this study. 相似文献
96.
M. Wolfsperger H. Wilfing K. Matiasek M. Teschler-Nicola 《International Journal of Anthropology》1993,8(1):27-33
Hair samples of 46 prehistoric mummies from five different pre-Inca sites in Peru were analyzed for Ca, Sr, Ni, Mn, and Ba
by DCP/AES. The five sites displayed differing burial customs: whereas the dead of Cahuachi (n=13), Huayuri (n=2) and Brujo
(n=5) had been interred unwrapped in simple stone pits, the mummies of Las Trancas (n=17) and Pacatnamu (n=9) had been granted
protection by fabrics and wooden coffins. At the sites with no protection, the hair samples contained extremely high concentrations
of Ca and Sr which by far exceeded the usual physiological ranges. This can probably be explained by contamination from the
surrounding soil. In contrast, the protected depositions of Las Trancas and Pacatnamu exhibited Ca and Sr concentrations within
the present range of variation. This may indicate that favourable conditions had prevented contamination in these cases. For
Mn the same trend can be observed, both Cahuachi and Huayuri samples showed markedly increased values. For Ni and Ba on the
other hand no correlation with the type of interment was found. In the two non-contaminated series, the mean values of Mn,
Ba, and Ni were considerably higher in Las Trancas than in Pacatnamu. As Mn, Ni, and Ba tend to occur in higher concentrations
in vegetable than in animal food items, these differences may indicate a differential availability of animal protein at the
two locations 相似文献
97.
Female fourth- and sixth-instar larvae, Choristoneura fumiferana, were tested individually for the response of the sugar cell on the lateral styloconic sensillum to 25 mM/l concentrations of 12 carbohydrates. The spruce budworm showed an age-related change in responsiveness of the sugar cell. The order of stimulating effectiveness for fourth-instars was melibiose > sucrose > raffinose.These storage di- and trisaccharides are present in the host plant at the beginning of budbreak. Sixth-instars responded to sucrose > fructose> m-inositol. These findings are in accordance with those of a previous behavioural study on feeding preferences of sixth-instars. The response for both melibiose and raffinose does not change from fourth- to sixth-instars; however, it does for sucrose, fructose and m- inositol. 相似文献
98.
High-throughput sequencing of hair follicle development-related micrornas in cashmere goat at various fetal periods 总被引:1,自引:0,他引:1
Yang Liu Lele Wang Xiaoyan Li Wenjing Han Kun Yang Honghao Wang Yanjun Zhang Rui Su Zhihong Liu Ruijun Wang Zhiying Wang Yanhong Zhao Zhixin Wang Jinquan Li 《Saudi Journal of Biological Sciences》2018,25(7):1494-1508
Inner Mongolia cashmere goat marks a precious gerplasm genetic resource due to its excellent cashmere traits. Therefore, it is of crucial importance to investigate the cashmere development mechanism of cashmere goat and to search for the important cashmere growth-related candidate genes. Fetal skin samples at 10 different periods of cashmere goat were collected in this research. Moreover, high-throughput sequencing was conducted on RNA samples from side skin of cashmere goat fetuses collected at three critical periods of skin hair follicle initiation, growth and development (namely, 45, 55 and 65?days) after balanced mix in line with the previous research results. Meanwhile, 3 samples at corresponding periods were used as the biological duplications. Data regarding microRNA and mRNA expression in skin and hair follicles of cashmere goats at various fetal periods were obtained using the high-throughput sequencing method. The results indicated that microRNAs in the oar-let-7 and oar-miR-200 families in 55?days and 66?days of pregnancy samples had been notably up-regulated relative to those in 45?days of pregnancy samples. This revealed that they might be the critical microRNAs in hair follicle development. 相似文献
99.
The concentrations of 19 trace element in hair samples from 1273 residents of Harbin (China), Medan (Indonesia), and Tokushima
(Japan) were measured by inductively coupled plasma emission spectrometry. The mean concentrations of Ba, Ca, and Se were
significantly higher in the Harbin hair samples when compared to those from Medan, but Al, B, Cu, Fe, Mn, Na, Pb, Ti, Zn,
and K were significantly higher in Medan than in Harbin hair samples. The differences in the mean concentrations of As, Cr,
Mg, P, Sn, and Sr between the Medan and Harbin lots were not significant. In the Tokushima hair samples, Na and K were significantly
higher, but As, B, Ba, Ca, Cr, Mg, Mn, Pb, Sn, Sr, and Se were significantly lower than in the Harbin hair samples. The differences
in the mean concentrations of Al, Cu, Fe, P, Ti, and Zn between Harbin and Tokushima were not significant. In the Medan hair
samples, Al, As, B, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Pb, Sn, Sr, Ti, and Zn were significantly higher, but P and Se were significantly
lower than in Tokushima hair samples. Differences in mean concentrations of Na and K between Tokushima and Medan were not
significant. 相似文献
100.
Summary Scanning electron microscopy revealed two types of hair cells in the sacculus of an amphibian, the mudpuppy (Necturus maculosus). Both types were surrounded by microvilli-covered sustentacular cells. The peripheral hair cells have shorter, thinner stereocilia and longer kinocilia than the hair cells in the central macula. The hair cells generally were found to be oriented with their stereocilia gradient directed toward the periphery of the macula. A nearly semicircular stria separated those directed forward and outward from those directed rearward and outward. Two basic types of otoconia were found in the otolith, and X-ray analysis revealed the entire otolith to be composed of aragonite.We would like to thank Dean E. Hillman for suggestions regarding fixation and interpretation, R. Eric Lombard for assistance with amphibian morphology and for helpful discussions during the course of this work, H. R. Wenk for performing X-ray analysis of otolith and Sister Loretta Shimondle for technical assistance. Research sponsored by the National Science Foundation Grant GK-3845 and the United States Public Health Service Grant GM-17523. 相似文献