Hair follicles and stages.

<p>Haematoxylin and eosin staining of dorsal skin from FVB/NCrl postnatal mice of different ages. (A) Actively growing anagen III and IV follicles from an SD I region from a postnatal day (d) 6 animal. Catagen II follicles in an SD IV region (B) and a catagen VIII follicle in an SD I region (C) from the same d15 animal. (D) Telogen follicle in an SD I region from a d20 animal. SD I regions with an anagen IIIA follicle from a d21 animal (E), and an anagen V follicle from a d28 animal (F). (G) The lower end of a catagen VI hair follicle regresses in an SD II region from a d38 animal. SD I regions with a telogen follicle from a d42 animal (H) and an anagen III follicle from a d70 animal (I). Scale bar: 50 μm.