Dermal Hair Papilla - Hair Matrix


Dermal hair Papilla

In the active growth stage lower part of hair follicle is wide like a knob (bulbus). Bulbus is formed of matrix cells and melanocytes. Small egg shaped dermal structure (dermal hair papilla) protrudes into hair bulbus.
Papilla ensures and maintains the growth of follicles.


Hair Matrix

Pluripotential cells of hair matrix of hair bulbus form hair and its inner root sheath. Outer root sheath, however, is like a downward extension of epidermis. Cells that form hair matrix have a characteristic ultra-structural shape.Between adjacent cells there are filaments from desmosomes to cell cytoplasm just as it is in epidermal keratinocytes. Between matrix cells there are fewer links to epidermal basal layer.This enables mobility of cells from matrix to upper parts of bulbus and suprabulbar region.Cells surrounding dermal papilla are precursors of hair fibril. Peripheral matrix cells on the other hand form inner root sheath.

In the suprabulbar part of follicle these cells have a longer and thinner shape and there are evident cell links. Cells’ dimensions and amount of cytoplasm increase. These changes are related with protein synthesis and water content. In this region golgi bodies are underdeveloped and there are a small number of vesicles near nucleus.

Depending on the color of hair in the melanocytes there are varying amounts of melanin. Melanin produced in these cells is transferred to hair cells next from the distal part of dendritic protrusions of cells by the use of phagocytosis.