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.

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.

Pattern formation in skin development.

The development of skin and cutaneous appendages in amniote embryos has been submitted to a large number of experimental investigations the results of which have led to a better understanding of the mechanisms whereby this multiform organ arises during embryonic development. In birds, the main appendages are the feathers and the foot scales. Their formation results from a series of inductive events between ectoderm (later epidermis) and subectodermal mesoderm (later individualized dermis).

Production of fibronectin and collagen types I and III by chick embryo dermal cells cultured on extracellular matrix substrates.

Dermal cells isolated from the back skin 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 (GAGs): hyaluronate, chondroitin-4, chondroitin-6, dermatan and heparan sulfates). The effect of these substrates on the production of fibronectin, of types I, III and IV collagen by cells was compared with that of culture dish polystyrene. Using immunofluorescent labeling of cultured cells, it was observed that, on all substrates, in 1-day and 7-day cultures, 85 to 95% of cells contain type I collagen in the perinuclear cytoplasm; label was absent from cell processes.

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).