The Biology of the Skin
Authors: Susan Cooper
Journal: Journal of the Royal Society of Medicine (2002)

Dermatology registrars are required to attend the Cambridge ‘biology of the skin’ course at an early stage of their training, to learn the basics of skin anatomy and function. Freinkel and Woodley's book, with a similar emphasis on core knowledge, would be an excellent companion to the course. The primarily American authorship covers the structure and function of the skin in a systematic way, from gross anatomy down to molecular biology and genetics. The editors' overall aim is to ‘teach skin biology in the context of practical settings’.

The chapter on the eccrine sweat gland is excellent, detailing the important thermoregulatory role of these glands. A little known fact is that collectively they can produce an astounding 4 L of sweat per hour. Up-regulation is part of acclimatization in a hot country, but as this process takes three to four weeks the average holidaymaker does not benefit.

The complex process of cutaneous wound repair is handled well, with detailed descriptions of the three phases of repair—inflammation, proliferation and remodelling. One of the puzzles of recent years has been how re-epithelialization is achieved, or in other words how keratinocytes migrate from the edge of a wound to cover a defect. It is now known that keratinocytes migrate by flattening their normal cuboidal shape and developing lamellipodia. In addition, actin filaments, working as drawstrings, pull the keratinocyte across the wound.

The important topic of skin ageing is discussed and the authors emphasize the distinctions between intrinsic ageing (happens to all) and photoageing (ultraviolet-light-induced). With intrinsic ageing, skin becomes thin, smooth, finely wrinkled and more transparent whereas photoaged skin is thickened, sallow and yellow and coarsely wrinkled. Throughout adult life the collagen content of the skin declines by roughly 1% per year. Sagging occurs because of disintegration of elastin fibres. Fortunately, help is available for photoaged skin since topical tretinoin can reverse some of the connective tissue changes by inducing collagen formation. However, prevention by avoiding too much sun is preferable.

There are a few curious editorial omissions. Eccrine sweat glands and sebaceous glands have their own chapter but apocrine glands get only the briefest mention. This is a pity since a discussion on pheromones would have been interesting. Subepidermal immunobullous and genetic disorders such as bullous pemphigoid and epidermolysis bullosa are covered well in the chapter on the basement membrane zone but similar important intraepithelial disorders such as pemphigus vulgaris and paraneoplastic pemphigus are not discussed. My only other gripe is that the discussion of investigation of skin disease ought to cover immunofluorescence in detail since this is the standard investigation for immunobullous disorders.

This is an excellent book that will be a welcome addition to any dermatology library. It succeeds in covering basic biology with a clinical perspective. Most dermatology registrars will wish to have a copy, because it contains all the information that we really ought to know but probably don't.