Histology of the Skin

Forslind, B. et al., Aspects on the physiology of human skin. Studies using particle probe analysis. (Invited and accepted paper to special issue of MRT on the molecular histology of the skin), Microsc. Res. Techniq., 38, 373, 1998. 

Biotin deficiency and the functional deficiency associated with lack of holo-carboxylase synthetase (Section 11.2.2.1), or biotinidase (Section 11.2.3.1), causes alopecia (hair loss) and a scaly erythematous dermatitis, especially around the body orifices. The dermatitis is similar to that seen in zinc and essential fatty acid deficiency and is commonly associated with Candida albicans infection. Histology of the skin shows an absence of sebaceous glands and atrophy of the hair follicles. The dermatitis is because of impaired metabolism of polyunsaturated fatty acids as a result of low activity of acetyl CoA carboxylase (Section 11.2.1.1). In biotin-deficient experimental animals, provision of supplements of long-chain 6 polyunsaturated fatty acids prevents the development of skin lesions (Mock et al., 1988a, 1988b Mock, 1991). 

Figure 7.2 (A), Histology of the skin prior to a medium-depth peel. Histology of the skin 6 months (B) and 12 months (C) following one medium-depth peel (Jessner s solution with 35% TCA combination)...

Mastocytosis is recognized in most patients because of the presence of characteristic cutaneous lesions [10]. A positive Darier s sign and/or histological examination of the skin using metachromatic stains, or by immunohistochemistry using antibodies to mast cell tryptase, helps confirm the diagnosis of cutaneous disease. 

Dermal/Ocular Effects. Histological examination of the skin and eyes of rats and mice exposed to 2,3-benzofuran by gavage for up to 2 years showed no compound-related lesions at the highest doses examined (250 mg/kg/day for acute-duration exposure, 500 mg/kg/day for intermediate-duration exposure, and 120 mg/kg/day in rats and 240 mg/kg/day in mice for chronic-duration exposure) (NTP 1989). Rats exposed to oral doses of 500 and 1,000 mg/kg/day of 2,3-benzofuran for 3-14 days exhibited a red ocular discharge, but this discharge was not characterized and no histological examinations were performed on animals in these dose groups (NTP 1989). 

The tissue-level (histological) defense systems are composed primarily of the skin and the mucous membranes mucosa) that line the airways, mouth, and other portions of the gastrointestinal system. Healthy, intact skin is probably the most important barrier against chemical or biological insults. 

Microscopically, the skin is a multilayered organ composed of many histological layers. It is generally subdivided into three layers the epidermis, the dermis, and the hypodermis [1]. The uppermost nonviable layer of the epidermis, the stratum corneum, has been demonstrated to constitute the principal barrier to percutaneous penetration [2,3]. The excellent barrier properties of the stratum corneum can be ascribed to its unique structure and composition. The viable epidermis is situated beneath the stratum corneum and responsible for the generation of the stratum corneum. The dermis is directly adjacent to the epidermis and composed of a matrix of connective tissue, which renders the skin its elasticity and resistance to deformation. The blood vessels that are present in the dermis provide the skin with nutrients and oxygen [1]. The hypodermis or subcutaneous fat tissue is the lowermost layer of the skin. It supports the dermis and epidermis and provides thermal isolation and mechanical protection of the body. 

Topical applications of retinoic acid derivatives reduce the visible signs of aging and of photodamage,266 though there is little correlation between the histologic changes and the clinical appearance of the skin. Initial improvement in fine wrinkling and skin texture correlates with the deposition of HA in the epidermis. 

A 37-year-old Japanese woman, who was taking penicillamine (500 mg/day) for systemic sclerosis, developed papules distributed in characteristic arcuate patterns of the skin of her neck (274). Histologically there was transepidermal elimination of degenerative elastic particles. 

A 36-year-old white woman with relapsing acute myeloid leukemia took ceftazidime (2 g tds) and aciclovir for febrile neutropenia and Herpes labialis. She developed an itchy rash and treatment was changed to imi-penem (500 mg qds for 5 days), vancomycin (1 g bd for 3 days), and gentamicin (2 mg/kg for 3 days) chemotherapy included idambicin, cytarabine, etoposide, ondansetron, and dexamethasone for 3 days. Within a few days the rash developed into blisters and erosions, affecting more than 80% of the skin. The diagnosis was confirmed histologically, and she subsequently died from shock (70). 

Most peels, to varying degrees, cause the same types of histological changes, whose clinical results lead to a more or less rejuvenating effect on all or part of the skin. 

Clinical results appear slowly and gradually, after histological improvement. The skin soon appears to be intensely hydrated, once the erythema has disappeared or subsided. Clinically, it takes a year for the rejuvenating action of tretinoin to show. Patients, who hope to see rapid... 

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