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Anatomy, physiology, and histology of the skin
Published in Michael Parker, Charlie James, Fundamentals for Cosmetic Practice, 2022
The epidermis is comprised of five structurally and functionally different strata, which can be easily remembered and recalled with the mnemonic “Come, Let’s Get Some Beers”. The first letter of each word corresponds with each layer: stratumcorneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale (Figure 4.1). Newly formed skin cells within the basal layer or stratum basale migrate outwards throughout their life cycle until they form the stratum corneum, the outermost layer comprised of the oldest keratinocytes. In this chapter, we discuss each of these layers in detail to gain an appreciation of their role in the skin, an organ that most of us take for granted.
Reconstruction
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Nadir I. Osman, Karl H. Pang, Christopher R. Chapple
Healing of superficial (partial thickness wound):Wounds such as superficial burns, abrasions, and split-thickness graft sites.Injury involves the epithelium and superficial dermis. The basal layer is preserved.Heal by re-epithelialisation → epithelial cells at the wound edge migrate to close the wound.
Radiotherapy: The Prevention of Secondary Effects, Radiodermatitis, and Long-Term Toxicity
Published in Paloma Tejero, Hernán Pinto, Aesthetic Treatments for the Oncology Patient, 2020
Acute damage occurs directly from the initial radiation dose when the first batch of basal cells is destroyed, although acute side effects become apparent on average 2–3 weeks after the start of therapy. The remaining cells become cornified and, therefore, break off faster than healthy skin. This process disrupts the balance between normal cell production in the basal layer and cell destruction on the surface of the skin and will appear as long as the treatment continues. Skin barrier dysfunction manifests as dryness, peeling skin, or scaling, such as folliculitis (rash), xerosis, pruritus, and hyperpigmentation. The skin becomes more sensitive to allergens and ultraviolet radiation, making it prone to infection. The main function of supporting skin care is to maintain the integrity of the epidermal barrier [5].
The Beneficial Effect on Pigmentation Using Laser Epilation as an Initial Treatment Approach for Becker’s Nevus in Asian Skin
Published in Journal of Cosmetic and Laser Therapy, 2021
Young-Jun Choi, Sunmin Yim, Gyoo Huh, Ga-Young Lee, Won-Serk Kim
Becker’s nevus (BN) is characterized by an acquired melanosis with hypertrichosis (1). Unilateral, well-demarcated, variable-sized, and coalescent brownish patches occur on the body at an early age. Hair growth is known to occur in the lesions when patients enter puberty. The clinical course of the disease suggests that androgenic hormones are involved in maturation of the lesion. This also explains why men have a higher prevalence of BN (2). Histologically, elongation of rete ridges, hypermelanosis, and basal layer hyperpigmentation are frequently observed in the epidermis of BN lesions (3). Expression of androgenic receptors is more heightened in the epidermis of BN patients than in other epidermal pigmented disorders (4). Therefore, BN treatment should include two different approaches: hair removal and depigmentation. Epilation, in particular, is a primary concern for adolescent and adult patients because it can modulate the main structure of the dermis and improve the response to subsequent treatment for pigmentation.
Netrin-1 plays a critical role in regulating capacities of epidermal stem cells upon ultraviolet-B (UV-B) irradiation
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Peng Wu, Yongqian Cao, Ran Zhao, Yibing Wang
UV light irradiation can be divided into three subtypes according to their wavelength: UV-A (320–400 nm), UV-B (280–320 nm), and UV-C (200–280 nm) [15]. Among them, UV-B irradiation has been recognized as a key environmental mutagen and carcinogen of epidermal cells. ESCs are an important component of the epidermal basal layer. Cells present in this layer bring about all epidermal structures, including a striated epidermis and epidermal appendages. All epidermal keratinocytes, keratinocyte stem cells and ESCs are vulnerable to attack by UV-B [16]. Repetitive exposure to UV-B irradiation accelerates premature ageing of the skin by disturbing cell turnover homeostasis and loss of the capacity of stem cells. UV-B acts as an important inducer of DNA damage in skin. UV-B irradiation-induced DNA damage causes undesirable dysregulation of the skin stem cell pool [17]. Impairment of stem cell capacities in ESCs gives rise to the failure of self-renewal and differentiation [18]. Loss of the capacities of ESCs interferes with the processes of skin homeostasis, wound healing and rebuilding. Importantly, loss of the capacities of ESCs has been linked with a variety of diseases, including unsuccessful diabetic wound repair [19]. In the current study, we aimed to investigate the effects of netrin-1 and its receptor UNC5b in the stem cell capacities of ESCs under the condition of UV-B irradiation.
Therapy for prevention and treatment of skin ionizing radiation damage: a review
Published in International Journal of Radiation Biology, 2019
José L. Soriano, Ana C. Calpena, Eliana B. Souto, Beatriz Clares
Figure 3 schematizes the main layers of skin. Dermis and epidermis are the two main layers of skin, which are separated by a dermal-epidermal junction protein thin layer called basement membrane. The epidermis is the outer region of human skin, which comes from the embryotic ectoderm and contains no blood vessels. It consists of stratified squamous epithelium primarily composed of keratinocytes and other types of cells such as melanocytes, Langerhans cells, and Merkel cells. The lowest portion of the epidermis is the basal layer, which is in contact with the basement membrane (Larcher et al. 2007). The basal layer contains proliferating cells undergoing continuous division and provides a source of cells that move up through suprabasal layers of the epidermis. Beneath the basement membrane is the dermis. The dermis, which is derived from mesoderm, is an underlying connective tissue that contains nerve and vascular networks, lymphatics, as well as epidermal appendages such as glands (sebaceous, endocrine and apocrine), hair follicles and nails. In both cases, in sebaceous glands and hair follicles, proliferation takes place. The former is in the basal layer of the sebaceous gland, and the latter is in the matrix cells of the hair bulb. Other types of cells in the dermis are fibroblasts, macrophages, and mast cells. Finally, the hypodermis is the connective and adipose tissue underlying the skin and located below the dermis. However, it is not actually considered as a part of skin.