The stratum corneum

I have been wanting to do this experiment ever since I saw Manu’s post on volcanoes on his skin and the tatoo post.  I essentially wanted to stain my skin and foldscope it. I had a somewhat erroneous idea that I might see some nucleated cells. I just had to do the experiment to see what would happen. It didnt start off as a planned experiment though. In fact, I was washing all my slides (100s or them) with soap, detergent and isopropanol. At the end of this uninspiring task, I thought staining my fingers would be a good way to round up the work. I used a desk lamp for illumination and observed them with a foldscope.

fingers

The first thing that struck me was my peeling dry skin (Winter!). The pictures are from two different locations of my right hand, one from the finger tip and the other around a hair follicle. In both the peeling outer layer is obvious.

Fig1

In all three instances of finger staining, the stains fell into the grooves of the skin. Iodine formed little brown particles, the particles of India ink accumulated in the valleys of the grooves on my skin. Methylene blue that stains the nucleus showed interesting spreading patterns, possibly because it was dissolved in ethanol.

iodine
Finger stained with iodine
ink
Finger stained with India ink
methylene blue
Finger stained with methylene blue

These patterns illustrate the nature of the outher layer of the skin epidermis, called the stratum corneum. This is composed of encucleated dead cells which is about 15-20 cells thick. Starting from the stratum basale, they migrate up to the top in 14 days to form the stratum corneum. The cells are highly  keratinized, without a nucleus or other organelles.  Perhaps a protein stain might have been interesting. The patterns also give an idea of the skin surface, one of our greatest innate defensive systems.

Foldscopes have tremendous scope for surface views. Here are a few more surface views. Pictures are labeled.

Surface views of Latex gloves, nail (ugh!) and green tape.
Surface views of Latex gloves, underneat my fingernail (ugh!) and green tape.

2 Comments Add yours

  1. Saad Bhamla says:

    @laks: Nice post ! Looks like reflection mode is up and working for you!
    the fingerprints with methylene blue look like meandering rivers.. makes me curious to think about scaling of the structures with age.. I’m wondering if there is a characteristic length scale there?

  2. laksiyer says:

    @Saad, I am sure there is some truth in what you say, but for me to do this experiment on myself, it will take me another 30 years of waiting, i.e. when I turn 50 :). However, wouldnt it be great if using some skin parameter we could estimate the age of the person. I am actually excited that I will be able to look at skin fungi which are commonly found on the faces of kids in winters in the North east US.

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