Glabrous Epidermis Research Articles

An Approach to Spermacoceae Cham. & Schltdl. sensu lato from the view-point of certain floral characters

Spermacoceae sensu lato is a tribe of the subfamily Rubioideae (Rubiaceae) that is referred in the literature with problems of generic delimitations. Recent investigations on the systematics, taxonomy and floristics of Brazilian species of Rubiaceae confirm this trend in the tribe, and suggest new phylogenetic and multidisciplinary studies on the group. In this context, the present paper aimed at the morphoanatomical analysis of the flowers of nine species of Spermacoceae, belonging to the genera Emmeorhiza, Galianthe, Mitracarpus, Richardia and Spermacoce, in order to indicate characters that have significant potential in the taxonomy and phylogeny of the tribe. Floral buds and flowers from vegetation in different environments were embedded in historesin and sectioned in a rotation microtome. Sepals exhibit glabrous or hairy epidermis and homogeneous mesophyll or they have atypical palisade parenchyma. Petals consist of hairy or glabrous epidermis and homogeneous mesophyll. Anthers are tetrasporangiate, and they possibly show dicotyledoneous anther wall formation. The ovary is inferior and probably appendicular in nature, consisting of mesophyll with parenchyma and precursor tissue of the sclerenchymatous pyrene of the fruit. Presence of compitum in the ovary and style characterizes the species as eu-syncarpous. The study revealed that floral structural characters related to the perianth, gynoecium and nectary have significant taxonomic potential within Spermacoceae sensu lato.

Molecular and morphological notes on Opuntia ser. Streptacanthae (Cactaceae)

A detailed morphological and molecular study of the four Opuntia species belonging to the ser. Streptacanthae is carried out. No published phylogenetic study of Opuntia includes these four species. Our data support the recognition of the four taxa as separated species but related by the characteristic of having a glabrous epidermis, yellow flowers, red and sweet fruits, in the present study it is recovered forming a monophyletic group within Opuntia s.str.

Micromorphology of leaflets of Senna series Bacillares (Leguminosae) and its taxonomic significance

Senna ser. Bacillares (Benth.) H.S.Irwin & Barneby comprises approximately 50 species, 23 of which are found in Brazil. Micromorphological studies of the leaflet epidermis were performed on ten species of Senna ser. Bacillares collected in the Atlantic Forest north of the São Francisco River, in Northeastern Brazil, to identify qualitative and quantitative characters supporting their taxonomy. All species showed a uniseriate epidermis, hypostomatic leaflets, and more than one type of stomata (the paracytic type being predominant). Different types of epicuticular waxes were observed, including microplatelets as rosettes (characteristic of Fabaceae), fissured layers, and membranous platelets. A glabrous epidermis on both surfaces was characteristic of Senna splendida (Vogel) H.S.Irwin & Barneby, and disperse trichomes were observed on the abaxial surface of Senna quinquangulata (Rich.) H.S.Irwin & Barneby. Straight to curved anticlinal cell walls were observed in most species, the curved pattern was exclusive to Senna quinquangulata and sinuous types on the abaxial surfaces of Senna macranthera (DC. ex Collad.) H.S.Irwin & Barneby and Senna splendida. A papillose epidermis on the abaxial surface was common to seven species. Four types of stomata were observed, including the anomotetracytic type, which has not been previously reported in Senna Mill. Spherical crystals and crystal sand are reported here for Senna for the first time. Those sets of micromorphological characters provide additional subsidies for the taxonomy of Senna ser. Bacillares, as well as for the genus Senna.

Use of Frozen Leaves for Morpho-anatomical Characterization of Nectandra megapotamica (Spreng.) Mez., Lauraceae

Nectandra megapotamica (Spreng.) Mez. it is a native tree species of the Atlantic Forest, commonly known as canela-preta. The species has some anti-inflammatory, antitumor and antirheumatic properties among others. In this work the use of frozen plant material for microscopy analysis was tested. In addition, the leaf morpho-anatomy of the species was characterized which allowed to perform a structural description and to identify structures of secretion and storage of essential oil. The plant material was prepared for analyzes in optical, fluorescence and scanning electron microscopy. The leaf anatomy shows glabrous epidermis, unistratified, paracytic stomata, absence of trichomes, polyhedral epidermal cells. Some typical family characteristics were observed as a closed arc-shaped bicollateral bundle vascular system and dorsiventral mesophyll. The structures of secretion and storage of essential oil were identified as secretory cavities.

Different requirements for GFRα2-signaling in three populations of cutaneous sensory neurons.

Many primary sensory neurons in mouse dorsal root ganglia (DRG) express one or several GFRα’s, the ligand-binding receptors of the GDNF family, and their common signaling receptor Ret. GFRα2, the principal receptor for neurturin, is expressed in most of the small nonpeptidergic DRG neurons, but also in some large DRG neurons that start to express Ret earlier. Previously, GFRα2 has been shown to be crucial for the soma size of small nonpeptidergic nociceptors and for their target innervation of glabrous epidermis. However, little is known about this receptor in other Ret-expressing DRG neuron populations. Here we have investigated two populations of Ret-positive low-threshold mechanoreceptors that innervate different types of hair follicles on mouse back skin: the small C-LTMRs and the large Aβ-LTMRs. Using GFRα2-KO mice and immunohistochemistry we found that, similar to the nonpeptidergic nociceptors, GFRα2 controls the cell size but not the survival of both C-LTMRs and Aβ-LTMRs. In contrast to the nonpeptidergic neurons, GFRα2 is not required for the target innervation of C-LTMRs and Aβ-LTMRs in the back skin. These results suggest that different factors drive target innervation in these three populations of neurons. In addition, the observation that the large Ret-positive DRG neurons lack GFRα2 immunoreactivity in mature animals suggests that these neurons switch their GFRα signaling pathways during postnatal development.

Opuntia tezontepecana, una Nueva Especie de Cactaceae del Estado de Hidalgo, México

Abstract. A new species of Opuntia Mill. (Cactaceae), endemic to the region of Villa de Tezontepec, in the state of Hidalgo, Mexico, is described. Farmers in the region call it “winter xoconostle” (in nahuatl, “xoco” = “acid”; “noxtle” = “tunas”). Opuntia tezontepecana Gallegos-Vazquez & Scheinvar is compared with the two sympatric species that have a glabrous epidermis to the unaided eye, but are pulverulent under SEM: O. joconostle F. A. C. Weber and O. matudae Scheinvar, both xoconostles. We observed the following distinctive characteristics in the new species: the mature cladodes as widely elliptic, the areoles in eight or nine series, spines on all areoles; spines and glochids structurally different from those of the sympatric species; the pericarpel with inconspicuous tubercles, without spines, but the superior ones with one or two bristles; fruits ellipsoid, with the floral scar slightly sunken, with a shiny epidermis, light green with red-orange spots, wide walls, acidic, rose-colored, edible; its...

Homo‐ and heterotypic cell–cell contacts in Merkel cells and Merkel cell carcinomas: heterogeneity and indications for cadherin switching

Merkel cell carcinomas (MCCs) are rare but aggressive tumours associated recently with Merkel cell polyomavirus (MCV). As development and progression of several types of carcinomas can be promoted by changes in cell adhesion proteins, the aim of this study was to examine homo- and heterotypic cell contacts of Merkel cells and MCCs. Merkel cells of healthy glabrous epidermis and 52 MCCs were analysed by double-label immunostaining, immunofluorescence and confocal microscopy. Merkel cells were connected to keratinocytes by E- and P-cadherin, desmoglein 2 and desmocollin 2. In contrast, the vast majority of MCCs (90%) contained N-cadherin, but only 67% and 65% contained E- and P-cadherin, respectively. Interestingly, P-cadherin was absent significantly more frequently in lymph node metastases than in primary tumours and by trend in more advanced clinical stages. Moreover, major subsets of MCCs synthesized desmoglein 2 and, surprisingly, tight junction proteins. No significant differences were observed upon stratification for MCV DNA, detected in 84% of tumours by real-time polymerase chain reaction. Assuming that MCCs originate from Merkel cells, our data indicate a switch from E- and P-cadherin to N-cadherin during tumorigenesis. Whether the unexpected heterogeneity of junctional proteins can be exploited for prognostic and therapeutic purposes will need to be examined.

Long‐Term Effects of Neonatal Capsaicin Treatment on Intraepidermal Nerve Fibers and Keratinocyte Proliferation in Rat Glabrous Skin

Innervation is required to preserve several aspects of skin homeostasis. Previous studies in rodents have shown that sciatic nerve transection leads to epidermal thinning and reduced keratinocyte proliferation. As the sciatic nerve is composed of sensory and motor axons, it is not clear whether skin alterations reflect motor or sensory disturbances. In this study, we used neonatal capsaicin treatment to evaluate whether sensory chemical denervation affects keratinocyte proliferation at 1, 3, and 6 months of age. Using design-based stereological methods, we estimated the total length of intraepidermal nerve fibers (IENF) that were of peptidergic type and the number of bromodeoxyuridine-labeled (BrdU(+) ) nuclei in the hind paw glabrous epidermis of control and capsaicin-treated rats. We found that the treatment decreased the total fiber length of IENF immunoreactive for both protein gene product 9.5 (PGP(+) ) and of IENF immunoreactive for calcitonin gene-related peptide (CGRP(+) ). The length of PGP(+) fibers decreased by 83%, 81%, and 77% and that of CGRP(+) fibers decreased by 48%, 58%, and 58% at 1, 3, and 6 months, respectively. Double-immunofluorescence staining for neural beta III tubulin and CGRP revealed that the majority of the remaining fibers in the epidermis after capsaicin treatment were of peptidergic type. The number of BrdU(+) nuclei was similar in both groups. Our findings suggest that IENF present after capsaicin treatment are sufficient to maintain epidermal replacement.

An innovative design for reconstruction of plantar heel by split partially overlapping anterolateral thigh flap

Introduction Reconstruction of the weight bearing, thick and durable heel, in soft tissue injuries of the foot remains a difficult and challenging problem. The thick glabrous epidermis and dermis, and the fibrous septae of the subcutaneous layer provide unique properties for withstanding pressure and shock associated with gait.

Evidence for distinct populations of human Merkel cells

Merkel cells (MCs) are neuroendocrine cells of unknown origin located in the skin. They are identified at electron microscopic level by electron dense granules, at light microscopic level by the presence of cytokeratins 8, 18, 19 and 20. Contradictory reports concerning the presence of other molecules of epithelial as well as neural origin prompted us to investigate whether there are distinct populations of human MCs. Here, we show the heterogeneous expression of villin, N-CAM, NGF-R, and neurofilaments in MCs. Synaptophysin is found in all MCs but with different intensity, nestin is absent. Expression patterns vary between interfollicular epidermis, hair follicles and glabrous epidermis. We conclude that there are distinct populations of MCs, but all populations contain markers for epithelial as well as neural cells. Putative functions of the distinct populations are discussed.

Morfo-anatomia da plântula e do tirodendro de Trichilia catigua A. Juss., T. elegans A. Juss. e T. pallida Sw. (Meliaceae)

This work intends to study, morphologically and anatomically, seedlings of Trichilia catigua A. Juss., T. elegans A. Juss. and T. pallida Sw., all belonging to the Meliaceae. The seedlings were obtained from seeds collected at the Horto Florestal in Maringa, state of Parana, Brazil. Fresh material was submitted to anatomical analysis and fixed in FAA 50. T. catigua and T. elegans seedlings are phanerocotylar, and T. pallida seedlings are phanerocotylar and cryptocotylar. The cotyledon is thick, with glabrous epidermis for T. catigua and T. elegans and pilose epidermis for T. pallida . The mesophyll is parenchymatic. The root is axial and tetrarch. The first eophyll is simple, and its thickness varies among the species. The metaphyll is compound. Eophyll and metaphyll are not significantly different from each other, being both dorsiventral, hypostomatic and with brochidodromous venation.

Micromorphology of the Labellum and Floral Spur of Cryptocentrum Benth. and Sepalosaccus Schltr. (Maxillariinae: Orchidaceae)

Gross vegetative and floral morphology, as well as modern molecular techniques, indicate that Cryptocentrum Benth. and Sepalosaccus Schltr. are related to Maxillaria Ruiz & Pav. However, they differ from Maxillaria in their possession of floral spurs and, in this respect, are atypical of Maxillariinae. The labellar micromorphology of Maxillaria, unlike that of the other two genera, has been extensively studied. In the present report, the labellar micromorphology of Cryptocentrum and Sepalosaccus is compared with that of Maxillaria and, for the first time, the micromorphology of the floral spur as found in Maxillariinae is described. Labella and dissected floral spurs of Cryptocentrum and Sepalosaccus were examined using light microscopy (LM) and scanning electron microscopy (SEM). In each case, the labellum consists of a papillose mid-lobe (epichile), a cymbiform region (hypochile) and, proximally, a spur, which is pronounced in Cryptocentrum but short and blunt in Sepalosaccus. The inner epidermal surface of the spur of Cryptocentrum is glabrous or pubescent, and the bicellular hairs, where present, are unlike any hitherto described for Maxillariinae. Similar but unicellular hairs also occur in the floral spur of Sepalosaccus, whereas the glabrous epidermis lining the spur of C. peruvianum contains putative nectar pores. The labellar micromorphology of Cryptocentrum and Sepalosaccus generally resembles that of Maxillaria. The floral spur of Cryptocentrum displays two types of organization in that the epidermal lining may be glabrous (possibly with nectar pores) or pubescent. This may have taxonomic significance and perhaps reflects physiological differences relating to nectar secretion. The trichomes found within the spurs of Cryptocentrum and Sepalosaccus more closely resemble the hairs of certain unrelated, nectariferous orchid taxa than those found in the largely nectarless genus Maxillaria, and this further supports the case for parallelism.

Embryonic dermal condensation and adult dermal papilla induce hair follicles in adult glabrous epidermis through different mechanisms

Hair induction in the adult glabrous epidermis by the embryonic dermis was compared with that by the adult dermis. Recombinant skin, composed of the adult sole epidermis and the embryonic dermis containing dermal condensations (DC), was transplanted onto the back of nude mice. The epidermis of transplants formed hairs. Histology on the induction process demonstrated the formation of placode-like tissues, indicating that the transplant produces hair follicles through a mechanism similar to that underlying hair follicle development in the embryonic skin. An isolated adult rat sole skin piece, inserted with either an aggregate of cultured dermal papilla (DP) cells or an intact DP between its epidermis and dermis, was similarly transplanted. The transplant produced hair follicles. Histology showed that the epidermis in both cases surrounded the aggregates of DP cells. The epidermis never formed placode-like tissues. Thus, it was concluded that the adult epidermal cells recapitulate the embryonic process of hair follicle development when exposed to DC, whereas they get directly into the anagen of the hair cycle when exposed to DP. The expression pattern of Edar and Shh genes, and P-cadherin protein during the hair follicle development in the two types of transplants supported the above conclusion.

Morfo-anatomia e aspectos da biologia floral de Nectandra megapotamica (Spreng.) Mez (Lauraceae)

Nectandra megapotamica (Spreng.) Mez é espécie freqüente nas matas secundárias da região de Maringá, Estado do Paraná, Brasil. A morfologia e estrutura de suas flores, bem como observações da antese, deiscência das anteras, receptividade do estigma e do registro de insetos visitantes são objetos do trabalho. A antese é diurna e as anteras só se abrem no segundo dia, quando o estigma não é mais receptivo. O comportamento da flor caracteriza a ocorrência de dicogamia. O inseto visitante mais freqüente pertence à Thysanoptera. As tépalas têm epiderme simples, com pêlos tectores e glandulares e complexos estomáticos paracíticos, e mesofilo parenquimático homogêneo. Os nectarios têm parênquima secretor com tecido vascular apresentando predominância de floema. As anteras possuem epiderme unisseriada pilosa, endotécio, duas ou três camadas médias e tapete com células binucleadas. O estigma apresenta pêlos multicelulares unisseriados. O ovário possui epiderme glabra, parênquima com atividade meristemática subepidérmica e fenda como região sutural vestigial. O único óvulo é pêndulo, anátropo e bitegumentado.

Adult epidermal keratinocytes are endowed with pilosebaceous forming abilities.

Pluristratified epithelia of adult vertebrate skin continuously regenerate from stem cells, and the question still arises as to whether those cells are committed to the production of only one cell lineage, or in contrast they conserve their embryonic pluripotentiality. In order to investigate the abilities of adult cultured as well as wound healing epidermis, heterospecific fibroblast-keratinocyte recombinations were performed, which allow unquestionable identification of the cells implicated in the structures that differentiate. Adult human cultured breast epidermal cells and full-thickness wound healing from human facial skin and foreskin were associated with either rabbit embryonic trichogenic dermis or cultured dermal papilla cells of adult rat, before grafting onto nude mice for two weeks to one month. In situ hybridization with a human specific sequence Alu probe labeled the human cells, whereas implanted rabbit or rat and host mouse cells were distinguished by the Hoechst staining of their nuclei. The results show that human adult cultured breast epidermal cells are able to form hair buds and to participate in hair follicle formation, while adult healing epidermis from a sparsely hairy skin as the human face or the dorsal skin of nude mouse, or even from a glabrous epidermis as the human foreskin, are able to differentiate pilosebaceous units. Although a follicular origin of the involved keratinocytes cannot be excluded in the three first cases, the formation of hair and sebaceous glands by foreskin keratinocytes of children 2 to 10 years-old establishes the cutaneous appendage ability of the interfollicular epidermal stem cells. The formation of interspecies mosaic follicles also highlights the fact that there must be a significant level of commonality in the interactive signaling molecules used by epithelial cells from different species.

CD24 (heat stable antigen, nectadrin), a novel keratinocyte differentiation marker, is preferentially expressed in areas of the hair follicle containing the colony-forming cells.

We have isolated, by subtractive and differential hybridization from a library constructed from keratinocyte colony-forming cells (K-CFCs), a cDNA coding for the rat CD24 (nectadrin, heat stable antigen). CD24, a glycoprotein thought to be involved in cell-cell adhesion and signalling, is highly expressed in keratinocytes located in the bulge area of the rat vibrissa which contains the most K-CFCs. CD24 is also expressed in the outer epithelial sheath of human hair follicles and in glabrous epidermis. However, its expression is not restricted to K-CFCs as demonstrated by cell sorting experiments, and it is thus not a specific marker of clonogenic keratinocytes. Rather, its preferential distribution in keratinocytes located in the most innervated area of the rat vibrissal follicle, i.e., the bulge, suggests that is function could be related to the tactile role of the hair follicle.

Optical Properties of Hairs During the Early Stages of Leaf Development in Platanus orientalis

Young, developing leaves of plane (Platanus orientalis L.) possess a dense hair cover on both surfaces but, as the leaf matures, the hairs of the upper surface abscise, leading to a glabrous epidermis. Leaf hairs strongly attenuate visible radiation, partly due to high reflectance of the trichome layer and partly to the presence of an absorbing pigment, tentatively identified as the anthocyanidin peonidin, which was present in the hairs of exposed young leaves but was absent on leaves harvested from the interior of the canopy. It is suggested that leaf hairs, apart from other functions, may protect developing leaves against the photoinhibitory effect of excess light.

Location of stem cells of human hair follicles by clonal analysis

We have examined the growth capacity of keratinocytes isolated from human scalp hair follicles. Like the keratinocytes of glabrous epidermis, most of the colony-forming cells are classified as holoclones or meroclones when analyzed in a clonal assay. Some of them have extensive growth potential, as they are able to undergo at least 130 doublings. Therefore, the hair follicle, like the epidermis, contains keratinocytes with the expected property of stem cells: an extensive proliferative capacity permitting the generation of a large amount of epithelium. We have also examined the distribution of clonogenic keratinocytes within the hair follicle. Several hundred colony-forming cells are concentrated at a region below the midpoint of the follicle and outside the hair bulb. This region lies deeper than the site of insertion of the arrector pili muscle, which corresponds with the position of the bulge when the latter can be identified. In contrast, few colony-forming cells are present in the hair bulb, where most of the mitotic activity is observed during the active growth phase of the follicle. Paraclones, which are present both in the midregion and in the bulb of hair follicles, are unlikely to be the transient amplifying cells expected from kinetic studies.

Induction of Hair Growth in Ear Wounds by Cultured Dermal Papilla Cells

In the adult hair follicle the dermal papilla plays a crucial role in the dermal-epidermal interactions that control hair production and events of the growth cycle. It has previously been shown that cultured cells from rat vibrissa follicle dermal papillae can stimulate hair growth when implanted into amputated follicles. This study investigated the effects of implanting low-passage cultured papilla cells into small incisional wounds in the rat ear pinna. The groups of fibers that emerged from wound sites were much larger than local hairs, and often had vibrissa-type characteristics. Later-passage papilla cells or cultured skin fibroblasts failed to elicit the same response. Histology revealed that big follicles were formed when papilla cells were trapped between the cut edges of the epidermis. Abnormally large follicles were seen at wound sites many months post-operatively. Independent of epidermal influence, cultured papilla cells in the wound dermis formed rounded papilla-like aggregates that also persisted until biopsy. A previously described method of wrapping papilla cells in glabrous epidermis was less successful in percentage terms but resulted in the production of one very large vibrissa-type follicle and fiber. These results further illustrate that the inductive powers and developmental information retained by cultured dermal papilla cells parallel the properties of their embryonic precursors; the findings may have implications for human hair growth.

Electric fields and wound healing

There are many points of view from which one may consider the healing of wounded skin, several of which are dealt with in earlier chapters. We would like to focus on one aspect of wound healing that has received only scant attention: the possible role of electric fields in the migration of epithelial cells that must occur in order to heal wounded skin. This cell migration is one of the earliest signs of epithelial repair of epidermal wounds, both in mammals and in amphibians. 1 One important reason for the lack of attention to electrical aspects of skin healing can be attributed to the paucity of information, useful to an understanding of wound healing, about the mammalian skin's ability to generate electrical currents. The bulk of the literature on the electrical properties of mammalian skin is concerned with psychophysiology. 2 4 There is some information about electrical properties of skin that may be relevant to wound healing. Some years ago, Herlitzka 5 confirmed DuBois-Reymond's 1860 observation 6 that about 1 microampere of current leaves small epidermal wounds made in human fingers when the wounds are immersed in saline. Much more recently. Illingworth and Barker 7 have found currents with densities ranging from 10 to 30 μA/cm 2 leaving the stumps of accidentally amputated children's fingertips when the stumps are immersed in saline. We, working with Barker, have added to this information 8 by studying the current-generating capacity of the glabrous epidermis of the cavy, and, particularly, the gradients of electrical potential that exist in the vicinity of wounds made in such skin. Subsequently, we have begun study of wound healing in a simpler system, larval Xenopus skin. We here will review this information, present some previously unpublished observations, and speculate on the possible relevance of this information to wound healing.