1. Do Hair Bulb Melanocytes Undergo Apotosis During Hair Follicle Regression (Catagen)? 
Desmond J. Tobin 
Journal of Investigative Dermatology 
Volume 111, Issue 6, Pages (December 1998)
DOI: /j x
Copyright © 1998 The Society for Investigative Dermatology, Inc Terms and Conditions

2. Figure 1
MC status in early catagen. (a) Hair follicle in spontaneous catagen I/II. Note the presence of melanin in precortical keratinocytes, but the absence of detectable MC in the bulb, despite the presence of a full DP profile. (b) Melanin incontinence within lysosomes in distal ORS keratinocytes. (c) MC apoptosis in spontaneous early catagen. Note typical morphologic features of apoptosis including cell shrinkage and nuclear condensation. (d) High magnification of inset in (c). Image is turned 180° from that in (c). The affected cells contain MC-specific premelanosomes. ly, lysosome; dp, dermal papilla; am, apoptotic MC; p, premelanosomes; m, melanosome; k, keratinocyte.Scale bars: (a) 20 μm, (b) 2 μm (inset, 5 μm), (c) 2 μm, (d) 0.5 μm (inset, 0.25 μm).
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 1998 The Society for Investigative Dermatology, Inc Terms and Conditions

3. Figure 2
MC status in DEX-induced early catagen. (a) Melanin incontinence was observed in the DP. (b) MC apoptosis. Note nuclear and cytoplasmic condensation and the presence of numerous MC-specific premelanosomes in addition to many fully mature, stage IV, melanosomes. am, apoptotic MC; k, keratinocyte; p, premelanosomes; m, melanosomes; dp, DP; pc, precortex.Scale bars: (a) 10 μm, (b) 1 μm (inset, 0.3 μm).
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 1998 The Society for Investigative Dermatology, Inc Terms and Conditions

4. Figure 3
MC status in CYP-induced early catagen. (a, b) Re-distribution of melanogenic MC to the most proximal ORS. Note also the presence of widespread keratinocyte apoptosis, some in very early stages of programmed cell death 10 d after CYP-treatment initiation. (c) Ectopic distribution of melanin granules within epidermal keratinocytes. (d) Presumptive MC apoptosis in CYP-induced catagen. Some apoptotic cells contain premelanosome-like granules. me, MC; a, apoptosis; m, melanin; cts, connective tissue sheath; k, keratinocytes; s, stratum corneum; p, premelanosome-like granules.Scale bars: (a) 10 μm, (b) 5 μm (inset, 1 μm), (c) 2 μm, (d) 1 μm.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 1998 The Society for Investigative Dermatology, Inc Terms and Conditions

5. Figure 4
Apoptosis of hair bulb melanocytes in spontaneous catagen. Cryostat sections of adolescent C57BL/6 skin, with all HF in early stages of spontaneous catagen (day 17 post-depilation), were processed for double immunostaining with TUNEL and TRP-1. Nuclei were counterstained with Hoechst Large arrowhead, TRP1-IR (red fluorescence) was detected in the keratogenic zone;small arrowheads, TUNEL expression (green fluorescence);arrows, co-localization of TRP1 and TUNEL (yellow fluorescence); DP, dermal papilla; HM, hair matrix; IRS, inner root sheath; ORS, outer root sheath.Scale bar: 50 μm.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 1998 The Society for Investigative Dermatology, Inc Terms and Conditions