Histology of the Skin

Hello all, I've tried to come up with some slides and pictures which can help you with tommorow's practical session. Here are a few compilations of slides which I compiled from some websites across the internet. Most of the explanation are of my own so forgive me if it's not really accurate. Enjoy!

CLICK ON THE PICTURES TO ENLARGE AND TO GET A BETTER VIEW.
(Sorry, the pictures look a little off coz its too big)

THICK SKIN The following picture shows the histology slide for thick skin. Things to note for is the thickened keratinized layer or the stratum corneum.

Here is a close up of that layer ( thick purple layer as shown below)

Here shows another view of the whole layer of thick skin.

THIN SKIN

Here is a picture of the thin skin: (Notice the much thinner stratum corneum layer as compared to the thick skin)

COMPARISON OF THICK AND THIN SKIN

Here is a side by side comparison of the thick and thin skin:

This plate shows the structural variation of the epidermis in different parts of the body.

The epidermis in all three areas is keratinized stratified squamous epithelium. The thickness varies from one site to the other. Note the marked thickness of the epidermis in C (palm). The epidermis of palms of the hands and soles of the feet is the thickest in the body. In these regions only four layers of the epidermis are well delineated.

SKIN APPENDAGES

Here are the labelled diagrams you can use for the pratical.

MELANOCYTES AND MELANOMA

Here is what melanocytes would look like:

(Notice the brown area? Those are the due to the production of melanin)

As you can see in this picture, the epidermal layer is much much more thicker in melanoma as compared to the normal skin. (Epidermal layer is the one in darker purple)

A closer view at 20x shows disorganisation of the cells. Not sure how else to describe it.

PSORIASIS

Four distinct pathological alterations characterise this disorder:

•		Inflammation.
•		Hyperproliferation of the epidermis
•		Altered maturation of the epidermis (resulting in scaling)
•		Vascular alterations (which add to redness).

Histology of psoriasis

1. Marked hyperkeratosis with parakeratosis (abnormal maturation)

2. Loss of granular layer

3. Epidermal acathosis and elongation of rete ridges (reflecting hyperproliferative state)

4. Vascular dilatation (these vessels are abnormal as well). Generalised inflammation can also be seen, with T-lymphocytes in the dermis and epidermis.

   For more info on this : Visit these websites!
   http://www.dermamed.com/tech_docs/psoriasis/psoriasis_lit.asp http://www.dermnet.com/thumbnailIndex.cfm?moduleID=15&moduleGroupID=462&groupIndex=0&numcols=0

Anatomy of the Skin (Integumentary System)

Hey guys...this is what i have found. I used Saladin, Wheater's and a website for this...i wont label the images nor post them up coz they cannot be uploaded here..so i will post the link for you guys to refer to the images aites?...the images cl..early show both thick and thin skin enjoy your night ppl

1. Draw and label a diagram showing histological features of thick skin
2. Draw and label a diagram showing histological features of thin skin for
comparison.
Answer: refer to website-
connectiondev.lww.com/Products/eroschenko/documents/.../Ch10.pdf



3. List the 4 major cell types in epidermis and state their function. What are the key changes seen in disorders involving melanocytes such as vitiligo & malignant melanoma.
Answer:
Keratinocytes-synthesize keratin by a process known as keratinisation or cornification.Keratinocytes of the stratum basale undergo mitosis and produce new epidermal cells to replace the dead ones that exfoliate (flake off) from the surface.

Melanocytes-synthesize the pigment melanin. They have long branching processes that spread among the basal keratinocytes and continually shed melanin-containing fragments from their tips. The keratinocytes phagocytize these fragments and accumulate melanin granules on the “sunny side” of the nucleus. Like a little parasol, the pigment shields the DNA from ultraviolet radiation. People of all skin colors have about equal numbers of melanocytes. Differences in color result from differences in the rate of melanin synthesis and how clumped or spread out the melanin is in the keratinocytes. In light skin, the melanin is less abundant and is relatively clumped near the nucleus, imparting less colour to the cells.

Merkel cells-relatively few in number, are receptors for the sense of touch. The tactile cell and its dermal nerve fiber are collectively called a tactile (Merkel) disc.

Langerhan’s cell-antigen presenting cells(APC),express a large number of lymphocyte and macrophage surface markers.

Vitiligo-common disease in which symmetrical areas of depigmentation of the skin occur,often on the hands,fingers and face. The disease destroys all the melanocytes in the affected skin and skin becomes glaringly white, the keratinocytes are not affected. It is an autoimmune disease and destroys the melanocytes.

Malignant melanoma-malignant tumour of melanocytes, particularly affecting pale-skinned people who are exposed to excessive UV light.


4. With the help of a diagram, highlight the microscopic features of the major skin appendages.
Answer:
Refer to Saladin 4th Ed integumentary System


5. What is psoriasis? Briefly describe the main histopathological features associated with this disease.
Answer:
The transition of keratinocytes from replicating basal cell,through the keratinocytes of the prickle cell layer(stratum spinosum), to the flattening and degenerating granular layer cells(stratum granulosum) packed with tonofibrils and keratinohyaline granules can be regarded as an efficient sequence culminating in the production of a tough resistant keratin layer on the surface of skin. The normal transit time is 50-60 days but psoriasis causes the transition to only take about 7 days. It isa common skin condition with unknown aetiology but with an element of multifactorial inheritance. The maturation process is so rushed that there is insufficient time for full development of tonofibrils and keratohyaline in the stratum spinosum and the granular layer does not form. Instead of normal keratin, there is a surface opaque white scale composed of a mixture of keratin and nuclear and cytoplasmic debris of keratinocytes. The rapidly proliferating epidermis is thickened to produce raised red patches under the white scale.


Hope it helps...XD....