Clinical and Experimentat Dermatotogy 1992; 17: 421-423.
The anchoring strengths of various chest hair root types D.M.CHAPMAN Anatomy Department, Dalhousie University, Halifax, Canada Accepted for publication 2Q January 1992
Summary
Materials and methods
The force required to epiiate singie chest hairs was measured electronicaiiy during a slow (0-09 m/s) machine-driven extraction. Teiogen hairs showed a mean anchoring strength of 70 g (s.d.— 16). Anagen hairs, with variabie amounts of surrounding root sheaths, had a mean of 71 g (s.d. —10) whereas bare anagen hairs had a mean of 66 g (s.d. = 13). The catagen phase had a mean of 62 g (s.d. ^8). It is highly iikeiy that the anchoring mechanisms of anagen and teiogen roots are as different physioiogicaiiy as these roots are different anatomically yet hoth are sufficiently strong to resist the ordinary tractions and puiiings to which hair is subject.
Two hundred and fifty single, straight, white chest hairs were mechanicaiiy piucked from a heaithy, Caucasian maie (the author) aged 55 years. Chest hairs were used because they have iarger foiiieies hence microdissection is easier' and because it aiiowed the author to experiment more readily on himseif. The epiiating apparatus is shown in Fig. i. A revoiving kymograph axie puiis on a suture thread attached to a carriage hoiding a 100 g force transducer (FTA series, Hewiett Packard, Waltham, MA, USA) wired to a recorder (Hewiett Packard 7702B). The carriage siides aiong a iow friction rail. A suture thread extends from the transducer to a smaii serrefinc vaseuiar ciamp which grips a hair. The chest is braced against a board to prevent disturbing movements. The kymograph is controiied by a remote controi switch and set to give a 009 m/s puii which is a speed producing both bare and ensheathed anagen hairs.'
This paper considers the anchoring strengths of the various terminai hair root types from the chest during a siow machine-driven extraction. The major root types are ciassified according to the growth phase: anagen, the growing phase in whieh the root is iong; catagen when the root shortens; and the teiogen in which the ciub-iike root is shortest. Teiogen roots are either firmiy anchored at first or iater are ioosely attached in the foiiicie. The eatagen phase has a spectrum of transitionai changes first marked by cessation of mitosis in the buib then a shortening of the root and its sheaths untii the inner root sheath is gone and the outer root sheath is ieft to form an epitheiiai sae around the teiogen ciub.' The sub-types of piucked anagen roots are partiy reiated to the speed of epiiationr siowiy piueked anagen hairs are usuaiiy bare (no sheaths) and have variousiy deformed buibs' and degrees of peeiing back (ruffles) of the root cuticle;^ quiekly piucked anagen hairs are usually ensheathed to various degrees hy the internal and externai root sheaths. The anehoring force for each of the above root types was measured and anaiysed as a step towards the future goal of determining the nature of the forces holding hair in the skin.
Correspondence: Dr DM.Chapman, Anatomy Department, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada,
Figure 1. Epilation apparatus below with cross-sectional view of carriage above. A force transducer t with a lead to a chart recorder is carried in a carriage c which is supported by two holders ss which are yoked at * and which are connected to the carriage by axles ax. All this slides along a low friction rail r, A rubber stopper s steadies the transducer, A bolt b is attached to a barbless fish-hook f which in turn IS attached to the axis of a kymograph k by a suture thread su. The chest skin sk is steadied against a brace br which is attached to the base ba, A small scrrefine vascular clamp cl grips a hair h. The clamp is hooked and tied with suture thread to the transducer.
421
422
DM.CHAPMAN
Each piucked hair was removed from the ciamp, mounted in 0 9% NaCi on a siide and coversiipped. The degree to whieh the anagen root was covered by each of the inner and outer root sheaths was noted as a percentage to the nearest 5%. The data were analysed graphicaiiy and statisticaiiy using JMP (SAS Inst. Inc. Cary, NC, USA) software with an Apple Macintosh II CX eomputer. IOO 80 70 60 Grams Figure 3. Histogram of the force (g) distribution for telogen hairs.
20
Results
40
30
50
The statistics for the various root types are given in Fig. 2. Telogen roots
The histogram showing the telogen hairs is given in Fig. 3. The distribution does not seem normai but is somewhat flattish. 0'
Catagen roots These are the ieast common hairs (Fig. 4). There is a great variety of forms in the spectrum from anagen to teiogen. The force frequency distribution in Fig. 4 is rather ievei and not normaily distributed.
50
55
go
65
70
75
80
'^'""^^ Figure 4. Histogram of the force (g) distribution for catagen hairs.
Ensheathed anagen roots
These roots are significantiy more strongiy anchored than either the bare anagen or catagen roots (Fig. 5). Both the inner and outer root sheaths may be whoiiy intact or eise diminished, aiways from the proximai end of 40 45 50 55 60 65 70 75 80 85 90 95 the root. The inner root sheath may equai the iength of Grams the outer root sheath or it may be ionger but never shorter Figure 5. Histogram of tbe force (g) distribution for variously than the outer one. ensheathed anagen hairs. How the piucking force is correiated with the percentage of the root covered by the inner root sheath and by the outer one can be determined. The piucking force and the degree to which the outer root sheath covers the root gives ^=-018909 (/'
The anchoring strengths of various chest hair root types D.M.CHAPMAN Anatomy Department, Dalhousie University, Halifax, Canada Accepted for publication 2Q January 1992
Summary
Materials and methods
The force required to epiiate singie chest hairs was measured electronicaiiy during a slow (0-09 m/s) machine-driven extraction. Teiogen hairs showed a mean anchoring strength of 70 g (s.d.— 16). Anagen hairs, with variabie amounts of surrounding root sheaths, had a mean of 71 g (s.d. —10) whereas bare anagen hairs had a mean of 66 g (s.d. = 13). The catagen phase had a mean of 62 g (s.d. ^8). It is highly iikeiy that the anchoring mechanisms of anagen and teiogen roots are as different physioiogicaiiy as these roots are different anatomically yet hoth are sufficiently strong to resist the ordinary tractions and puiiings to which hair is subject.
Two hundred and fifty single, straight, white chest hairs were mechanicaiiy piucked from a heaithy, Caucasian maie (the author) aged 55 years. Chest hairs were used because they have iarger foiiieies hence microdissection is easier' and because it aiiowed the author to experiment more readily on himseif. The epiiating apparatus is shown in Fig. i. A revoiving kymograph axie puiis on a suture thread attached to a carriage hoiding a 100 g force transducer (FTA series, Hewiett Packard, Waltham, MA, USA) wired to a recorder (Hewiett Packard 7702B). The carriage siides aiong a iow friction rail. A suture thread extends from the transducer to a smaii serrefinc vaseuiar ciamp which grips a hair. The chest is braced against a board to prevent disturbing movements. The kymograph is controiied by a remote controi switch and set to give a 009 m/s puii which is a speed producing both bare and ensheathed anagen hairs.'
This paper considers the anchoring strengths of the various terminai hair root types from the chest during a siow machine-driven extraction. The major root types are ciassified according to the growth phase: anagen, the growing phase in whieh the root is iong; catagen when the root shortens; and the teiogen in which the ciub-iike root is shortest. Teiogen roots are either firmiy anchored at first or iater are ioosely attached in the foiiicie. The eatagen phase has a spectrum of transitionai changes first marked by cessation of mitosis in the buib then a shortening of the root and its sheaths untii the inner root sheath is gone and the outer root sheath is ieft to form an epitheiiai sae around the teiogen ciub.' The sub-types of piucked anagen roots are partiy reiated to the speed of epiiationr siowiy piueked anagen hairs are usuaiiy bare (no sheaths) and have variousiy deformed buibs' and degrees of peeiing back (ruffles) of the root cuticle;^ quiekly piucked anagen hairs are usually ensheathed to various degrees hy the internal and externai root sheaths. The anehoring force for each of the above root types was measured and anaiysed as a step towards the future goal of determining the nature of the forces holding hair in the skin.
Correspondence: Dr DM.Chapman, Anatomy Department, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada,
Figure 1. Epilation apparatus below with cross-sectional view of carriage above. A force transducer t with a lead to a chart recorder is carried in a carriage c which is supported by two holders ss which are yoked at * and which are connected to the carriage by axles ax. All this slides along a low friction rail r, A rubber stopper s steadies the transducer, A bolt b is attached to a barbless fish-hook f which in turn IS attached to the axis of a kymograph k by a suture thread su. The chest skin sk is steadied against a brace br which is attached to the base ba, A small scrrefine vascular clamp cl grips a hair h. The clamp is hooked and tied with suture thread to the transducer.
421
422
DM.CHAPMAN
Each piucked hair was removed from the ciamp, mounted in 0 9% NaCi on a siide and coversiipped. The degree to whieh the anagen root was covered by each of the inner and outer root sheaths was noted as a percentage to the nearest 5%. The data were analysed graphicaiiy and statisticaiiy using JMP (SAS Inst. Inc. Cary, NC, USA) software with an Apple Macintosh II CX eomputer. IOO 80 70 60 Grams Figure 3. Histogram of the force (g) distribution for telogen hairs.
20
Results
40
30
50
The statistics for the various root types are given in Fig. 2. Telogen roots
The histogram showing the telogen hairs is given in Fig. 3. The distribution does not seem normai but is somewhat flattish. 0'
Catagen roots These are the ieast common hairs (Fig. 4). There is a great variety of forms in the spectrum from anagen to teiogen. The force frequency distribution in Fig. 4 is rather ievei and not normaily distributed.
50
55
go
65
70
75
80
'^'""^^ Figure 4. Histogram of the force (g) distribution for catagen hairs.
Ensheathed anagen roots
These roots are significantiy more strongiy anchored than either the bare anagen or catagen roots (Fig. 5). Both the inner and outer root sheaths may be whoiiy intact or eise diminished, aiways from the proximai end of 40 45 50 55 60 65 70 75 80 85 90 95 the root. The inner root sheath may equai the iength of Grams the outer root sheath or it may be ionger but never shorter Figure 5. Histogram of tbe force (g) distribution for variously than the outer one. ensheathed anagen hairs. How the piucking force is correiated with the percentage of the root covered by the inner root sheath and by the outer one can be determined. The piucking force and the degree to which the outer root sheath covers the root gives ^=-018909 (/'
