Search results for "epidermis"
showing 10 items of 151 documents
Keratinocytes Determine Th1 Immunity during Early Experimental Leishmaniasis
2010
Experimental leishmaniasis is an excellent model system for analyzing Th1/Th2 differentiation. Resistance to Leishmania (L.) major depends on the development of a L. major specific Th1 response, while Th2 differentiation results in susceptibility. There is growing evidence that the microenvironment of the early affected tissue delivers the initial triggers for Th-cell differentiation. To analyze this we studied differential gene expression in infected skin of resistant and susceptible mice 16h after parasite inoculation. Employing microarray technology, bioinformatics, laser-microdissection and in-situ-hybridization we found that the epidermis was the major source of immunomodulatory mediat…
Tormogen cell and receptor-lymph space in insect olfactory sensilla. Fine structure and histochemical properties in Calliphora.
1978
(1) The basiconic sensilla on the antennae of Calliphora resemble other insect epidermal sensilla; one or several bipolar sense cells are surrounded by three non-neural cells. (2) The apical cell membrane of the tormogen cell (one of the three accessory cells) forms microvilli coated internally with particles. (3) In the (extracellular) outer receptor-lymph space hyaluronic acid can be demonstrated histochemically. (4) Demonstration of non-specific alkaline phosphatase, Mg2+-activated ATPase, and the presence of mitochondria in the apical part of the tormogen cell suggest active transport processes through these cells into the outer receptor-lymph space.
Sun exposure and PDZK1 genotype modulate PDZK1 gene expression in normal skin
2020
Human skin pigmentation results from the enzymatically controlled synthesis of melanin pigments in specialized organelles (melano‐somes) produced within epidermal melanocytes, followed by their transfer to neighboring keratinocytes and their distribution through‐out the epidermis.1 Constitutive skin pigmentation seems to be mostly genetically determined,2 being altered by numerous intrinsic and extrinsic factors affecting the epidermal melanin unit
Do nonmelanoma skin cancers develop from extra-cutaneous stem cells?
2008
A hypothesis is presented that nonmelanoma skin cancers can develop from extra-cutaneous stem cells, and not exclusively from skin keratinocytes. This idea is supported by recent findings regarding the initiation of cancers in the digestive tract, and by a cancer stem cell model of a neoplasia. It is known that multipotent adult progenitor cells can trans-differentiate into very diverse cellular lineages and can be recruited to areas of profound tissue injury. In these settings, they might also initiate malignant transformation. Some epidemiological data and recent findings regarding mechanisms of wound healing indicate that skin cancers could also originate from bone marrow-derived or othe…
Preparation protocols for SEM visualization of charred fossil plants: the case of Weichselia reticulata pinnule anatomy
2021
The cosmopolite Mesozoic fern Weichselia reticulata presents many peculiarities in the anatomy of its stem as well as in the architecture of its leaves. Previous analyses of the ultrastructure of their pinnule laminas provided some insight on xeromorphic traits. In this work new protocols for the preparation of charred compression foliage specimens embedded in a limestone matrix for their observation under SEM are presented, which enhance the observation of different plant tissues. The preparation with HCl allows for the visualization of the whole lamina, from the upper to the lower epidermis, which had not been done to date. Additionally, collodion, latex, or wax coverings of the fossils b…
DNA Content and Synthesis in Several Tissues and Variation of Moulting Hormone-Level in Gryllus bimaculatus DEG (Ensifera, Insecta)
1983
The mode of growth of several tissues in Gryllus bimaculatus was investigated during postembryonic development by cytophotometric methods. In contrast to the situation in holo- metabolous insects, the tissues growing by endomitosis reach only moderate levels of polyploidy. In this case the growth of tissues is achieved by mitotic divisions of small cells with subsequent polyploidization. The time courses of DNA synthesis were measured within the 3rd and, for comparison, the 8th larval instar by incorporation of labelled thymidine followed by autoradiography. Hemocytes, cells of the regeneration crypts of the midgut, gonads and nervous tissue showed a continuous incorporation rate; by contra…
Chemical skin carcinogenesis is prevented in mice by the induced expression of a TGF-β related transgene
1995
Skin papillomas and squamous cell carcinomas (SCCs) are induced in mice by tumor initiation with a carcinogen followed by tumor promotion with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). These usually arise from preneoplastic lesions characterized by epidermal proliferation and hyperplasia, dermal edema, and inflammation. To evaluate the role of polypeptide growth factors in chemically induced skin carcinogenesis, we used transgenic mice carrying the cDNA for a TGF-β related molecule, bone morphogenetic protein-4 (BMP-4), under the control of the regulatory elements of the cytokeratin IV* gene in a skin carcinogenesis protocol. Control non-transgenic littermates and BMP-4 …
The mammary pheromone of the rabbit: from where does it come?
2005
Newborn rabbits, Oryctolagus cuniculus, are directed to their mother's nipples by specialized odour cues. Previous investigations have suggested that these cues are released from the doe's abdominal surface from structures located around the nipple. We tested pups with samples of various cutaneous tissues or fluids collected from lactating females to determine the location of the source of the odour cues. After finding that the nipples from lactating does were more attractive than those of virgin females, we conducted three experiments using skin samples collected at increasing distance from the nipples, dermal and mammary tissues taken below the nipples, and milk collected at different lev…
Ectopic expression of desmin in the epidermis of transgenic mice permits development of a normal epidermis.
2002
Cell architecture is largely based on the interaction of cytoskeletal proteins, which include intermediate filaments (IF), microfilaments, microtubules, as well as their type-specific membrane-attachment structures and associated proteins. In order to further our understanding of IF proteins and to address the fundamental issue whether different IF perform unique functions in different tissues, we expressed a desmin transgene in the basal epidermis of mice. Ectopic expression of desmin led to the formation of an additional, keratin-independent IF cytoskeleton and did not interfere with the keratin-desmosome interaction. We show that ectopic expression of a type III IF protein in basal kerat…