GLOSSARY

  • Bulb

Prominent, onion-shaped thickening on the proximal end of the hair follicle. Consisting of relatively undifferentiated matrix cells, Hair follicle melanocytes, as well as of proximal Outer Root Sheath cells ORS.

  • Bulge

Convex extension on the distal part of the hair follicle which consists of closely packed mesenchymal cells framed by the enlarged bulb matrix on the distal end.

  • Dermal Papilla DP

A mesodermal part of the hair follicle which consists of closely packed mesenchymal cells framed by the enlarged bulb matrix on the distal end.

  • Hair Canal

Tube-like connection between epidermal surface and most distal part of Inner Root Sheath IRS demarcated by surrounding Outer Root sheath. 

  • Hair Germ

Bud-like thickening of the pre-germ plaque in the epidermis with concave proximal end which surrounds partially a compact ball of mesenchymal cells in the dermis.

  • Hair Shaft

Composed of trichocytes (= terminally differentiated hair follicle keratinocytes) organized in the form of hair cuticle, cortex and medulla and surrounded by the inner root sheath (or ORS at the level of hair canal) 

  • Inner Root Sheath IRS

Multi-layered structure composed of terminally differentiated hair follicle keratinocytes surrounded by the ORS, consisting of the pale epithelial layer or Henle’s layer as well as Huxley’s layers and cuticle which cover the hair shaft up to the hair canal.

  • Ischmus

Small part of the hair follicle between insertion of sebaceous gland and the bulge. 

  • Outer Root Sheath ORS

Outmost sheath of hair follicle keratinocytes which merges distally into the basal layer of epidermis and proximally into the hair bulb.

  • The shaft

Which is considered the part of the hair above the skin surface though it appears first in the epidermis. The hair shaft, in cross-section, can be divided roughly into three zones. Starting from the outside.

  • The Cuticle

Which consists of several layers of flat, thin cells laid out like roof shingles.

  • The Cortex

Which contain the keratin bundles in cell structures that remain roughly rod like and in some cases

  • The Medulla

A disorganized and open area at the fibbers centre