Search PubMed⌕ Search

Biomedical subjects

A Mauger

Publications and source records attributed to A Mauger.

At least 37 records · Page 2Linked to original sources
PubMed1992

Cellular and extracellular involvement in the regeneration of the rat lower vibrissa follicle.

The sequence of events leading to the reconstruction of a fibre-producing hair follicle, after microsurgical amputation of the lower follicle bulb, has been detailed by immunohistology and electron microscopy. The initial response was essentially found to be a wound reaction, in that hyperproliferative follicle epidermis quickly spread to below the level of amputation--associated with downward movement of mesenchymal (or dermal) sheath cells. Fibronectin was prominent in both dermis and epidermis at this stage and, as in wound repair, preceded laminin and type IV collagen in covering the lower dermal-epidermal junction. Once a new basal line of epidermis and a complete basement membrane were established, laminin and type IV collagen were detected below this junction and within the prospective papilla-forming mesenchyme. This coincided with ultrastructural observations of profuse sub-basement membrane extracellular material in the region of new papilla formation. The glassy membrane displayed extensive ultrastructural modifications at its lower level, and these corresponded with localized variations in staining intensities for all three antibodies over time. The membrane hung below the level of the epidermis, and was crossed by migrating cells from the mesenchymal dermal sheath of the follicle - it acted to segregate the inner group of follicular dermal cells from wound fibroblasts. Extracellular matrix may be a mediator of the dermal-epidermal interactions associated with this hair follicle regeneration phenomenon.

Animals↗
PubMed1992

Changes in fibronectin, laminin and type IV collagen distribution relate to basement membrane restructuring during the rat vibrissa follicle hair growth cycle.

Hair growth in adult mammals involves continuous dermal-epidermal interaction across the follicular basement membrane, and repeated reorganisation of lower follicle structure during the hair growth cycle. The immunolocalisation of 3 extracellular matrix components, fibronectin, laminin and type IV collagen was investigated during the course of the rat vibrissa follicle growth cycle, and their distribution correlated with changes in cellular and extracellular ultrastructure, particularly around the basement membrane zone. Laminin and type IV collagen were omnipresent at the follicular dermal-epidermal junction, but were also seen in granular extracellular form within the inner dermal component of the follicle, the dermal papilla. Both the inner papilla-epidermal junction and the thick specialised outer basement membrane (the glassy membrane) revealed labelling by these 2 antibodies around telogen (the period of nonfibre production). By contrast, fibronectin was abundant within the anagen dermal papilla but at telogen stained the dermal-epidermal junction heterogeneously, when it disappeared from the inner papilla-epidermal interface but intensified externally. These changes to extracellular matrix distribution coincided with a modification of basement membrane ultrastructure from a relatively uniform line at anagen, to one which became much broader and multilayered at telogen with a loss of definite structure within the papilla. This shows that the lower part of the vibrissa follicle retains the capacity for very rapid basement membrane modification and remodelling, and implies that it is part of the biological process which enables dermal-epidermal signalling, rather than a secondary product of physical changes to the appendage. The work supports the idea that dermal papilla cells could contribute to basement membrane formation, and also that fibronectin may be involved in regulating cellular activities within the follicle. In the vibrissa follicle, dynamic cellular activity clearly takes place throughout the duration of the hair cycle.

Animals↗
PubMed1989

Influence of various extracellular matrix components on the behavior of cultured chick embryo dermal cells.

Dermal cells isolated from the back of 7-day chick embryos were cultured on homogeneous two-dimensional substrates consisting of one or two extracellular matrix components (type I, III or IV collagen, fibronectin and several glycosaminoglycans: hyaluronate, chondroitin-4, chondroitin-6, dermatan or heparan sulfate). The effect of these substrates on cell behavior was compared with that of culture dish polystyrene. Three parameters of cell behavior were examined: cell proliferation and patterning, spreading (cell surface) and locomotion (velocity and directionality). Data were collected by sequential microphotography and analyzed by computer assisted morphometry. Types I and III collagen, hyaluronate and heparan sulfate had a slowing down effect on cell proliferation and patterning. The inhibitory effect of type I collagen was also detected in mixtures with glycosaminoglycans. The other components had no effect. While the smallest spreading was observed on fibronectin substrate, the largest was recorded on chondroitin-6 sulfate and heparan sulfate. The slowest velocity of locomotion was measured on fibronectin, types I and IV collagen and a mixture of type I collagen and chondroitin-6 sulfate. The fastest speed was recorded on chondroitin-4 sulfate. These effects are discussed in view of our knowledge of the role of the dermis in the development of skin and cutaneous appendages, and in the light of the morphogenetically related microheterogeneous distribution of collagens, fibronectin and various glycosaminoglycans in the developing skin.

Animals↗
PubMed1988

Origin and development of avian skeletal musculature.

Experimental studies have shown that the myogenic stem cells in birds migrate from the somite into the lateral plate mesoderm, where they later differentiate into muscle cells. Muscles being made up of myocytes and connective tissue cells, the interactions between these two types of cells of different embryological origins have been considered during the development of the musculature. In particular, our purpose was to focus on the genesis of the spatial organization of the musculature; we have taken advantage in this field of research of an embryological muscular dysgenesis in which the muscles lose their patterning.

Animals↗