Received 4 March 2016; accepted 24 April 2016; published 27 April 2016

ABSTRACT

Aim: We have studied the only found three skin debris (P1, P2 and P3) deposited on the Face area of our sample of the Turin Shroud. Methods: P1, P2 and P3 were explored by optical microscopy, by SEM and by EDX analysis. Results: All P1, P2 and P3 are true skin debris, as observed in optic and electronic microscopy; their elementary compositions show organic matter, plus a sulphur peak that corresponds to keratin. P1, P2 and P3 are constituted of layers of corneocytes; in P3, which is certainly a human skin debris, we can observe both the epidermis and some residual dermis.

Keywords:

Turin Shroud, Face Area, Skin Debris, Optical Microscopy and SEM, EDX Analysis

1. Introduction

The Turin Shroud (TS) is a well-known object in which a body image is imprinted ( Marion & Lucotte, 2006 ). In 1978 and in 1988, Giovanni Riggi di Numana took some samples and dusts ( Riggi di Numana, 1988 ) of the TS, at areas corresponding to Hands, Face (a 1978 sample taken on the Face area was deposited by him on a special sticky-tape), Feet, Buttocks and the ¹⁴C area. We had access to this sticky-tape, cutted up in a triangular form, and realised on it preliminary investigations ( Lucotte, 2012 ) concerning mineral particles.

I have recently published three other studies on the triangle: the first one ( Lucotte, 2015a ) concerned linen (and other textile) fibers. The second ( Lucotte, 2015b ) concerned pollens (and spores); and the third ( Lucotte, 2015c ) red blood cells.

Desquamed epithelial cells―named as “skin debris” (SD)―were previously studied by SEM-EDX ( Varetto, 1990 ; DeGaetano et al., 1992 ), specially in a forensic science perspective ( Burnett, 1995 ). In the present study, we describe in details some SD located on the triangle surface.

2. Materials and Methods

The material ( Lucotte, 2012 ) is a small (1.36 mm high, 614 μm wide) sticky-tape triangle (Figure 1,

the end of this article) at the surface of which the portions of fibers, pollen grains, red-blood cells and some plaques of organic matter were deposited.

More than 2500 particles, greater than 1 μm = 1 μ, can be observed at the surface of the triangle. All of them were studied by optical microscopy, SEM (Scanning Electronic Microscopy) and EDX (Energy Dispersive X-ray) analysis. For practical reasons, the surface of the triangle was subdivided into 19 sub-samples areas (areas A to S), the area E being subdivided in five sub-areas E.a to E.e), containing almost all the particles observed. The positions of each particle sticking to the triangle surface were located in a double system of coordinates (in 186 adjacent squares of 50 × 50 μ of the total surface).

Cell debris of the samples were observed, without any preparation, on the adherent part of the surface of the triangle. The observations were conducted by SEM, using a Philips XL30 instrument (environmental version); GSE (Gaseous Secondary Electrons) and BSE (Back Scattering Electrons) procedures were used, the last one to detect heavy material. Elemental analyses for each skin debris were realised by X-ray microfluorescence (XRMF), this SEM microscope being equipped with a Bruker AXS energy dispersive X-ray (EDX); the system of analysis is PGT (Spirit Model, of Princeton Gamma Technology).

Our SEM studies were completed by the optical observations of cell debris numbers 1, 2 and 3 (using a photomicroscope Zeiss, model III, 1972) and by their study in cross-polarized light (with the petrographic version of this microscope).

3. Results

As an example, Figure 2 shows the aspect (in SEM) and the EDX spectrum of a little layer of skin corneous

cells taken on the face of a 30-years old living man. We see on the SEM photography several large superposed corneous cells. EDX analysis of one of them shows an elementary composition rich in organic matter (carbon, oxygen and nitrogen) and a secondary peak of sulphur (keratin); also in the spectrum are little peaks of chlorine and sodium (ClNa: salt of the sweat) and of calcium (residual minerals deposited on the skin surface).

We have found only three SD on the triangle:

The a37 particle, located in the A area

This particle is the first SD (designated as P1) observed on the surface of the triangle. The SEM photography of Figure 3 shows the mean characteristics of the visible part of P1: it is a little surface (of about 10 μ of length) of skin, with two layers at least, the upper one being rough in aspect.

The P1 spectrum shows peaks corresponding to the constitutive elements (carbon, oxygen and sulphur) of the skin and of the sweat (chlorine and sodium). But the major secondary peaks of the spectrum are those of silicium and calcium; magnesium and aluminium (and probably also potassium and iron) are elements associated to silicium, to constitute a clay mineral of the montmorillonite-illite type ( Lucotte, 2012 ).

Figure 4 gives another P1 spectrum; here elements are quantified, to distinguish between those being skin specifics to those concerning mineral deposits. The calcium component represents about 23.4% of all elements (carbon and oxygen expected); the silicate component (comprising silicium, plus aluminium and magnesium) represents about 41% of the total. So, this P1 SD fragment is importantly covered by mineral clay deposits.

It seems that there are remarkable similarities (Figure 5), both in aspect and in composition, between P1 and a SD fragment of some part of my own finger skin (a clean SD, detached at the top of one of my finger). We suggest that P1 is a SD finger fragment originating from some of the many persons that have touched, in the past

(because it is now covered by mineral deposits, accumulated since the time), the TS; but further studies on P1 are problematic, because its most important surface part is covered by a thin plastic layer (Figure 3), impermeable to electrons.

The e2 particle, located in the E area (in sub-area E.a)

This particle is the second SD (designated as P2) observed on the triangle. The two SEM photographies of Figure 6 show the main characteristics of P2: it corresponds to a relatively large surface (maximal length of about 17 μ) of an ovaloïd skin fragment. The right upper border of P2 had some depth, with at least four layers.

The P2 surface is also rough. The below photography of Figure 6 (taken in BSE) indicates that the P2 surface is entirely covered with a relatively heavy material.

Figure 7 gives the P2 spectrum. This SD is mainly composed of organic matter (carbon and oxygen), plus

sulphur (keratin); there are some traces of chlorine (and Na). But the calcium peak is very elevated, and the silicium peak is at the same level to that of sulphur. Quantification shows that―among the non-carbon and oxygen elements―the silicate component (silicium, aluminium and magnesium) represents only about 14.2% of the total, while the calcium component is at more than 66%. We conclude that the surface of the P2 skin fragment is mainly covered by a calcium carbonate deposit.

The e6 particle, located also in the Ea sub-area

This particle is the third SD observed on the triangle, and is designated as P3. The SEM photography of Figure 8 shows its main characteristics: it corresponds to a large surface (maximal length of about 35 μ) of an elongated skin fragment. We can see, at the right upper part of the fragment, that it had some depth (because at least three layers are visible). The P2 lower part is adjacent to the upper part of P3 (Figure 6).

The P3 surface is sleek, with some micro-spines (Figure 8 and Figure 11). We can distinguish on its surface some linear little reliefs that could correspond to cell limits of the keratinocytes.

The spectrum below the photography of Figure 8 shows the elementary composition of P3 in its center. The predominant peaks (carbon and oxygen) are those of the organic matter, and there is a little peak of sulphur. Among the little peaks the chlorine peak is the most elevated, and there are some traces of sodium; there are also little peaks of calcium, and of silicium-aluminium-magnesium.

Both versions (in GSE and BSE) of the whole P3 particle are shown on Figure 9 photographs. The retro-dif- fused view shows that almost all of the border of the upper-half P3 surface is covered by a thin layer of some matter, which is richer in heavy elements than the rest of the uncovered P3 surface.

Elementary analysis were realised both for a covered and an uncovered P3 surfaces (spectrums at the black points a and b on the photography of Figure 10, respectively). The spectrum corresponding to the black point a (an uncovered surface) is identical to that shown in Figure 8.

But the spectrum corresponding to the black point b (the most intensively covered surface portion) is distinct,

for the little peaks upper spectrum of Figure 10), of these two last spectrums by two singularities: 1) A sodium peak appears; in that composition, sodium is not necessary linked to chlorine. 2) A nitrogen peak appears also; this relatively important level of nitrogen had probably something to do with a local “putrefaction process” of the P3 surface at this point.

The SEM photograph of Figure 11 shows the enlarged (×10,000) square of the P3 area showed on Figure 10 photograph. That permits to compare the smooth surface of the border of organic matter to that, delicately patterned and spinned, of the keratinocytes.

Study of the P1, P2 and P3 particles by optical microscopy

Figure 12 photographs concern optical views (in polarized light) of the A and E areas of the triangle, where particles P1, P2 and P3 are located. In Figure 12, photograph the entire P1 surface is shown; but is mostly covered (Figure 13) by a PVC plastic film, so not suitable to SEM-EDX analysis; the uncovered P1 surface can be distinguished on the photography, at a zone neighbouring the p38 particle (but this uncovered P1 surface is also partially masked by the triangle left border portion). The P1 particle of SD, yellow-grey in colour, does not show any birefringency when illuminated in polarized light.

Figure 12 photography shows that in its center the P2 and P3 particles are clearly identified by their shapes and sizes. The P2 surface shows birefringency (because of its elevated charge in calcium carbonate) when illuminated in polarized light, but that is not the case for the P3 surface, which had a relatively low calcium carbonate content. At each side of the P3 particle of SD can be distinguished the two h1 and h2 groups of red blood cells ( Lucotte, 2015c ); other adjacent P3 particles are not visible on the photography, because of masks (particles deposited at the surface, on the other side of the sticky-tape of the triangle).

The location of the P2 particle of the photography of Figure 12―determined by its position at the upper P3 border, and by its distance far from the right part of the e1 filament―is different to that shown in the SEM pho-

tography (that of the upper Figure 6 photography). As optical photographs of the triangle were taken about one year before to those taken in scanning electron microscopy, we conclude that the P2 particle was not well fixed on the surface of the sticky-tape of the triangle; it partially separates from the substrate and displaces its relative position during this time interval. Probably, the P2 particle represents in fact some form of contaminating SD material.

4. Discussion

We have found three skin debris (SD)―designated as P1, P2 and P3―at the surface of a sticky-tape triangle sampled on the Face of the Turin Shroud (TS). These SD are similar, both in ultrastructure and elementary composition, to that of one SD sampled on the face of a living man. Structurally these three SD, that have some thickness, are constituted of several layers (illustrated in Prost-Squarcioni et al., 2005 ) and they look like desquamed skin fragments. The rough surface of P1 is similar to that of jointed corneocytes (stratum corneum) of the epiderm superficial part; the finely spinned surface of P3 is similar to that of jointed keratinocytes (stratum spinosum) of the epiderm lower part ( Breathnach, 1975 ). Chemically they are rich in organic matter, with a marked peak of sulphur that corresponds to keratin; the P2 surface is completely covered by calcium carbonate, that hitchs to see its surface ultrastucture.

Table 1 summarizes the main characteristics (concerning elementary analysis) of the three SD P1, P2 and P3. Clays are more abundant on the P1 surface. Probably because of the relatively greater P3 size compared to the other two, individualized minerals and metallic particles (accumulated here since time) are deposited on its surface.

A possibility remains that the three skin debris observed could be those of rabbit skin, a sort of glue commonly used in the painting process in some portraits. Figure 14 shows a SEM photography of particles contained in a commercial rabbit skin glue. Rabitt skin debris are voluminous SD, with an important sickness (that

Footnote: + : moderate level; ++: consistant level; +++: elevated level.

means that both epiderm and derm layers are present). Some packs of collagen micro-filaments (not found on the triangle surface) surround the rabbit skin debris (Figure 15) shows the peaks corresponding to organic matter and the keratin (the elevated chlorine peak corresponds mainly to salt involved in the conservative process of the skin).

Proof of the human nature of the P3 skin debris is given by the observation of the two red blood cells groups neighbouring this SD : the h1 (e5 particle) group―the hematy group h16-18 ( Lucotte, 2015c )―and the h2 (e22 particle) group―the hematy group 19-20 ( Lucotte, 2015c )―shown in Figure 9. The e5 particle adheres to (is part of ) the P3 skin debris; as the human type of the red blood cells h16 - 18―like other red blood cells observed on the triangle surface ( Lucotte, 2015c )―was proved, we infer the human nature of the P3 skin debris also. The whole of the P3 SD plus the h1 group of hematies constitutes rests of some part of a human bleeding skin.

The P1 skin debris is probably a human corneous fragment exfoliated from a finger top (where epiderm is thicker). The important calcium carbonate deposit that covers the whole P2 skin debris renders it unsuitable for further analysis.

Table 2 summarizes the five successive histological layers (Prost-Squarcioni et al., 2005) of the human epidermis, from the exterior to the dermis. Skin debris P1 and P2 are constituted of the superficial layer of the cornified corneocytes only. For the SD P3―which is thicker―all the epidermal layers are conserved, because we observe on the surface (Figure 11) micro-spines characteristics of the stratum spinosum of keratinocytes; examination of the composition of the organic matter (Figure 10) deposited on almost all of the basal surface that there is also here some dermis micro-fragments.

Corneocytes are death-cells, without nucleus and DNA. Skin debris P3, composed of epiderm and derm layers attached, provide us an unique material to study by molecular genetics techniques the genomic components of the corresponding individual. Our current study on P3 concerns genomic DNA extractions from this peculiar skin debris.

5. Conclusion

We have found three skin debris (P1, P2 and P3) on the surface of a sticky-tape joined to the Face area of the

Turin Shroud. The largest one, P3, is the only one that comprises both epiderm and some part of derm layers. So, it is an excellent target tissue candidate to explore the DNA of the individual who exfoliated his skin debris on the Shroud.

Acknowledgements

We thank T. Derouin (Phanerogamy Department of the Natural History Museum of Paris) for allowing us to use his photomicroscope, and T. Thomasset (Analysis of a Physico-Chemistry Service of the UTC of Compiègne) for his precious help in SEM-EDX analysis.

Cite this paper

Gérard Lucotte, (2016) Skin Debris on the Face of the Turin Shroud: A SEM-EDX Analysis. Archaeological Discovery,04,103-117. doi: 10.4236/ad.2016.42008

References