Topic
Root sheath
About: Root sheath is a research topic. Over the lifetime, 245 publications have been published within this topic receiving 7173 citations.
Papers published on a yearly basis
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Papers
TL;DR: The results suggest that cadherins present in epidermal cells are involved not only in maintaining the arrangement of these cells but also in inducing dermal condensation.
Abstract: Expression and the role of E- and P-cadherin in the histogenesis of the surface epidermis and hair follicles were examined using the upper lip skin of the mouse. P-cadherin is expressed exclusively in the proliferating region of these tissues, that is in the germinative layer of the surface epidermis, the outer root sheath and the hair matrix. E-cadherin is coexpressed in these layers but this molecule was also detected in non-proliferating regions such as the intermediate layer of the surface epidermis and the immature regions of the inner root sheath. Neither P- nor E-cadherin was detected in fully keratinized layers such as the horny layer of the surface epidermis, the outermost layer of the outer root sheath and the mature hair fibres. These two cadherins were not detected in dermal cells. We cultured pieces of the upper lip skin in vitro in the absence or presence of a monoclonal antibody to E-cadherin (ECCD-1) or to P-cadherin (PCD-1). In control cultures, skin morphogenesis normally occurred in a pattern whereby the hair follicles grew and dermal cells were condensed to form the dermal sheath. A mixture of ECCD-1 and PCD-1, however, induced abnormal morphogenesis in the skin in several respects. (1) The cuboidal or columnar arrangement of basal epithelial cells was distorted. (2) Hair follicles were deformed. (3) Condensation of dermal cells was suppressed, causing a homogeneous distribution of these cells. These results suggest that cadherins present in epidermal cells are involved not only in maintaining the arrangement of these cells but also in inducing dermal condensation.
218 citations
TL;DR: It has been suggested that the dermal papilla may be involved in both the induction of follicle lengthening and hair growth during the proanagen phase of the hair cycle, a concept now justified by direct experimentation in the vibrissa follicle at least.
Abstract: Hair follicles are essentially composed of two tissues. The inner epidermal component, which gives rise to, among other products, the keratinized hair shaft, is confluent with the surface epidermis and is ensheathed by the dermal component which is confluent with the pars papillaris of the dermis. A specialization of the dermal component is the dermal papilla which, in follicles producing hair, is enclosed by the epidermal matrix of the hair bulb and is connected to the dermal sheath by the papilla stalk. Many authorities have considered that the dermal papilla is an essential component of the hair follicle (reviews: Cohen, 1965; Oliver, 1969). It has been suggested that the dermal papilla may be involved in both the induction of follicle lengthening and hair growth during the proanagen phase (Chase, 1965) of the hair cycle, a concept now justified by direct experimentation in the vibrissa follicle at least (Oliver, 1967b), and perhaps also in determining the nature of the hair produced by a follicle.
214 citations
TL;DR: Findings indicate that this Bmp signaling pathway, required for tooth initiation, does not regulate root development, but it is suggested that root shape may be regulated by a mechanism similar to that regulating crown shape in cap-stage tooth germs.
Abstract: Like crown development, root formation is also regulated by interactions between epithelial and mesenchymml tissues. Bone morphogenetic proteins (BMPs), together with the transcription factors Msx1 and Msx2, play important roles in these interactions during early tooth morphogenesis. To investigate the involvement of this signaling pathway in root development, we analyzed the expression patterns of Bmp2, Bmp3, Bmp4, and Bmp7 as well as Msx1 and Msx2 in the roots of mouse molars. Bmp4 was expressed in the apical mesenchyme and Msx2 in the root sheath. However, Bmps were not detected in the root sheath epithelium, and Msx transcripts were absent from the underlying mesenchyme. These findings indicate that this Bmp signaling pathway, required for tooth initiation, does not regulate root development, but we suggest that root shape may be regulated by a mechanism similar to that regulating crown shape in cap-stage tooth germs. Msx2 expression continued in the epithelial cell rests of Malassez, and the nearby c...
199 citations
TL;DR: In situ hybridization experiments described in the present study localized the amelin message to epithelial cells adjacent to the peripheral surface of newly deposited dentin in the root end and to cells embedded in cellular cementum in molars.
Abstract: Since 1974, when Slavkin and his collaborators proposed the epithelial origin of cementum, many experiments have been carried out to provide evidence for deposition of enamel-related proteins along the root surface. However, neither amelogenin nor other proteins have fully satisfied expectations. In previous studies, we have identified a novel mRNA coding for an extracellular-like protein which we called amelin. It was expressed at high levels in secretory and postsecretory ameloblasts in rat molars and incisors. In situ hybridization experiments described in the present study also localized the amelin message to epithelial cells adjacent to the peripheral surface of newly deposited dentin in the root end and to cells embedded in cellular cementum in molars. In incisors, the amelin RNA positive cells were detected in the area where cementum formation had been initiated. No amelogenin RNA signal was found in the cells at the root surface. We postulate that the epithelial cells of the root sheath as well as the ameloblasts are synthesizing amelin which might be one of the key proteins coupled to the process of cementogenesis.
149 citations
TL;DR: Biotinylated hyaluronan (HA) binding complex from bovine articular cartilage proteoglycan was used as a histological probe to study the localization of HA in human skin and it is suggested that in epithelia with divergent differentiation programs the functions of CD44 and HA may be different.
Abstract: Biotinylated hyaluronan (HA) binding complex (HABC) from bovine articular cartilage proteoglycan was used as a histological probe to study the localization of HA in human skin. The distribution of HA was compared with its presumptive cell surface receptor, CD44, using monoclonal antibodies. In epidermis both HA and CD44 were found in the basal and spinous cell layers, but neither was present in the stratum granulosum and stratum corneum. In the keratinizing parts of hair follicles, i.e. in the outer and inner epidermal root sheath, pilosebaceous duct and the actual hair, HA and CD44 were found between the vital but not the terminally differentiated cells. In the sebaceous glands a small amount of HA was found around all cells, whereas CD44 was restricted to the basal cell layer. The secretory acini of the sweat glands stained intensively with anti-CD44 antibodies but only weakly with HABC. In the sweat gland, CD44 was localized on the basal and lateral surfaces of the clear cells, whereas the dark cells and the myoepithelial cells were negative. Both the lower and upper layers of the sweat gland ducts showed a faint but constant staining for CD44 and only minor amounts of HA. While in the keratinizing skin epithelia both HA and its CD44 receptor showed an intense staining with a close co-distribution, in the sweat and sebaceous glands their distribution patterns were not similar. It is suggested that in epithelia with divergent differentiation programs the functions of CD44 and HA may be different.
144 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 1 |
| 2019 | 2 |
| 2018 | 2 |
| 2017 | 4 |
| 2016 | 5 |
| 2015 | 4 |