Squamous epithelia represent a morphologically and differentiation-dependent stratified tissue. The stem cells are located in the bulge region of hair follicles or in the basal layer of interfollicular epidermis and in the limbus of the cornea. This article summarizes the data about the glycobiological aspects of squamous epithelia cell differentiation under physiological as well as pathological conditions in relation to the function of this epithelial tissue. The entries about the LC, Merkel cells and melanocytes are also mentioned. The employment of the described data in the diagnostics of carcinomas derived from this type of epithelium as well as in the cell therapy of skin defects are shown.

• MeSH
• aglutininy chemie   MeSH
• biologické modely MeSH
• buněčná diferenciace MeSH
• epidermální buňky MeSH
• epitel patologie   MeSH
• fenotyp MeSH
• karcinom metabolismus   MeSH
• konkanavalin A farmakologie   MeSH
• kůže patologie   MeSH
• Langerhansovy ostrůvky cytologie   MeSH
• lektiny MeSH
• lidé MeSH
• melanocyty metabolismus   MeSH
• Merkelovy buňky metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• aglutininy MeSH
• konkanavalin A MeSH
• lektiny MeSH

Merkel nerve endings are mechanoreceptors in the vertebrate skin. They were named after the person who first described them--F.S. Merkel (1875). They consist of large, pale cells with lobulated nuclei forming synapse-like contacts with enlarged terminal endings of myelinated nerve fibres. Inside the cell are intermediate filaments formed of simple cytokeratins and osmophilic granules containing variety of neuropeptides. In mammals, they can be found in the basal layer of the skin and in those parts of the mucosa, which is derived from ectoderm. In contrast, in birds these cells are located in the dermis. The largest accumulation of Merkel nerve endings was found in whiskers of most mammals apart from man. There has been a controversy concerning the origin of Merkel cells. Results from chick/quail chimeras and most recently also from double transgenic mice have shown that Merkel cells are derived from the neural crest. Merkel cell play a role in the mechano-transduction process. In response to mechanical stimuli calcium ions enter Merkel cell and trigger the release of neurotransmitter probably glutamate. Thus, Merkel cell appears to be essential for characteristic slowly adapting response of these receptors during maintained mechanical stimuli. Cells in the skin of a similar appearance as Merkel cells are probably part of the diffuse neuroendocrine system and they do not function as mechanoreceptors. These cells, rather than those in mechanoreceptors, are most likely the origin of the highly malignant skin cancer called Merkel cell carcinoma.

• MeSH
• lidé MeSH
• Merkelovy buňky * cytologie   fyziologie   ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• přehledy MeSH

We have investigated the developmental origin and ultrastructure of avian Merkel cells by electron microscopy and chick/quail transplantation experiments. On embryonic day 3, chick leg primordia were homotopically grafted onto Japanese quail host embryo. Fourteen days later, quail cells that had migrated into grafted chick legs were identified according to the masses of heterochromatin associated with the nucleolus that are characteristic for quail. Both in chick and quail, Merkel cells are usually located in the dermis just below the epidermis. They are placed between nerve terminals either individually or in small groups wrapped in sheaths that are formed by glial cell processes. Occasionally, some Merkel cells appear in nerve fascicles and within Herbst corpuscles. Merkel cells, as well as glial cells, in grafted chicken legs were of quail origin. This finding provides evidence against the epidermal origin of avian Merkel cells and indicates that Merkel cells are derived from neural crest cells that colonise, together with glial cells and melanocytes, the developing limb primordium.

• MeSH
• Coturnix * MeSH
• crista neuralis embryologie   MeSH
• elektronová mikroskopie MeSH
• křepelky a křepelovití embryologie   MeSH
• kuřecí embryo embryologie   MeSH
• Merkelovy buňky ultrastruktura   MeSH
• transplantační chiméra embryologie   MeSH
• zadní končetina embryologie   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo embryologie   MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Auxiliary structures of the cutaneous sensory nerve formations (SNF) are dependent on sensory innervation during their critical period of development. Denervation of mature cutaneous corpuscles results in survival of the terminal Schwann cells and the capsular structures which are probably responsible for successful reinnervation of the cutaneous SNF. In addition, the basal lamina tubes of Schwann cells are connected with the terminal Schwann cells and play an important role in the guidance of regrowing axons to their original targets. Long-lasting denervation causes atrophic changes of the terminal Schwann cells and alterations of their molecular equipment. These atrophic changes in the terminal Schwann cells may be responsible for erroneous reinnervation of cutaneous SNF. A population of the cutaneous Merkel cells surviving denervation may also serve as targets for regrowing sensory axons. The basal laminae of terminal Schwann cells are produced under control of the sensory terminals during maturation of cutaneous SNF. In adult animals, the basal laminae are capable of stimulating differentiation of migrated Schwann cells to the terminal Schwann cells without the presence of the sensory terminals. Nonspecific cholinesterase (nChE) is secreted by the terminal Schwann cells and is attached to their extracellular matrix. The synthesis of these molecules in adult animals is not influenced by the sensory terminals. However, the presence of nChE molecules is associated with living terminal Schwann cells. Fetal orthotopically grafted dorsal root ganglion (DRG) neurons have the ability to reinnervate cutaneous SNF of adult hosts. When cutaneous areas are denervated, axons from adjacent sensory nerves may extend collateral branches into this area. The capacity for such extension is dependent on: (1) type of sensory nerve ending, C and A delta fibers having significantly greater capacity than sensory axons of larger caliber; (2) age of the animal, immature animals generally showing a greater capacity for collateral sprouting; (3) the state of the adjacent axons, those already in a growth mode being more capable than "resting" ones; and (4) the regional and mechanical conditions at the site of denervation, hindpaw skin being much less extensively reinnervated by collateral fibers than that of the trunk.

• MeSH
• axony fyziologie   MeSH
• krysa rodu Rattus MeSH
• kůže inervace   MeSH
• mechanoreceptory fyziologie   MeSH
• Merkelovy buňky fyziologie   MeSH
• regenerace nervu * MeSH
• Schwannovy buňky fyziologie   MeSH
• senzorická ganglia růst a vývoj   fyziologie   MeSH
• spinální ganglia fyziologie   MeSH
• transplantace fetální tkáně MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH