Zone of HOHL refers to:
1. Cell-free zone (Zone of weil)

Width approx. 40 µm
Not always present
Absent in young pulp (Active secretion of primary dentine) and older pulp (tertiary dentine)

CONTENTS

Capillaries
Unmyelinated nerve fibers
Cytoplasmic process of fibroblasts

2. Cell Rich Zone (Zone of HOHL)

Most numerous cells are fibroblasts
Fibroblasts secrete Type I and Type III collagen
Also contains undifferentiated mesenchymal stem cells.
Vascular supply is extensive and more than cell free zone and odontoblast zone.
Cell-free zone.
Cell rich zone.
Pulp proper.
None.