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Anatomy, physiology, and histology of the skin
Published in Michael Parker, Charlie James, Fundamentals for Cosmetic Practice, 2022
The dermis is found sandwiched between the epidermis and subcutaneous tissues and is comprised of papillary and reticular layers. The more superficial papillary layer is composed of a looser mesh of connective tissue than the underlying reticular layer and has fimbriae-like projections into the stratum basale of the epidermis in the form of dermal papillae. Multiple cell lines can be found within the papillary layer, including fibroblasts, adipocytes and phagocytes, as well as blood vessels, lymphatic capillaries and nerve fibres. The highly vascular nature of this layer allows it to undertake key functions including thermoregulation and supplying much-needed nutrients to the more superficial epidermis. The deeper reticular layer contains a high concentration of collagen fibres, aligned perpendicularly to the surface of the skin as well as densely packed cells, allowing it to contribute to the flexibility and tensile strength of the skin. It also helps support other structures within the skin, such as hair follicles and sweat glands. The reticular layer has an extensive neuronal network of both afferent sensory and efferent sympathetic fibres, allowing for the sending and receipt of important neuronal signals.
Comparative Anatomy, Physiology, and Biochemistry of Mammalian Skin
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The dermis can be divided into two anatomical layers; an outer papillary and an inner reticular layer. The papillary layer is the thinnest and consists of loose connective tissue, while the reticular layer is thicker and consists of dense connective tissue.197–199
The Integumentary (Dermatologic) System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
Ulcers occur when the epidermis and papillary layer of the dermis are destroyed. These are found most frequently on the legs and feet, usually from disturbances in circulation. Pressure sores (also called bedsores or decubitus ulcers) occur at weight-bearing sites when movement is severely limited. Patients who remain in a lying position will rapidly develop skin necrosis at the sacrum, spine, and heels, causing bedsores. Those on their sides will ulcerate in the hip area. Stasis ulcers occur with swelling in the lower extremities, the ulcer being formed as a result of stasis of the blood.
Site-specific drug delivery in the skin for the localized treatment of skin diseases
Published in Expert Opinion on Drug Delivery, 2019
Yang Chen, Xun Feng, Shengnan Meng
Underneath the epidermis lies the dermis, a 1–2 mm layer composed mainly of fibroblasts in an extracellular matrix of collagen and elastic fiber. It can be divided into the superficial papillary layer, and the lower reticular layer. The dermis layer comprises the bulk of the skin, and it also contains hair follicles, sweat glands, sebaceous glands, sensory nerve endings, lymphatic vessels, and blood capillaries, as well as immune cells including dermal dendritic cells, macrophages, T cells, and mast cells [5,31]. These immune cells are thought to play important roles in parasitic infections, psoriasis induction, tumor progression, dermal inflammation, angiogenesis, wound healing, tissue remodeling, skin sensitization, and tolerance [31,32]. Therefore, regional accumulation in the dermis is necessary for the activities of many drugs that are intended for the prevention and treatment of these local skin diseases. As an important component of the skin associated lymphoid system (SALT), the dendritic cells, as well as their subsets, are suggested to be involved in the initiation and regulation of many immunologic responses. In contrast to the Langerhans cells which mainly induce cellular immunity, the dermal dendritic cells preferentially activate humoral immunity. Novel strategies have been proposed for their use as the targets for the development of both prevention and therapeutic vaccines, as well as for immunological treatment of allergy, tumors and autoimmune diseases [33].
Nanocrystal: a novel approach to overcome skin barriers for improved topical drug delivery
Published in Expert Opinion on Drug Delivery, 2018
Viral Patel, Om Prakash Sharma, Tejal Mehta
Dermis is a layer below the epidermis which consists of dense connective tissues. It is divided into two layers, the papillary layer, which is adjacent to the epidermis, and the reticular layer, which is the deep thicker layer. Fibroblasts, macrophages, and adipocytes form the major cellular portion of the dermis. Apart from them, dermis also consists of matrix components such as collagen, elastin, and extrafibrillar matrix. Collagen is known for its tensile strength and forms a major portion of the dermis, while elastin is known for the flexibility. Dermis contains important receptors such as mechanoreceptors (act toward the sense of touch) and thermoreceptors (act toward the sense of heat). Dermis is the home for glands including sweat glands, sebaceous glands, and apocrine glands. Dermis is highly vascularized with a rich supply of blood and lymphatic vessels; however, there is no blood supply across the dermal–epidermal junction. These blood vessels supply nutrition and carry away the waste from both the dermis and epidermis layers [29].
Erythema multiforme following exposure to the herbicide atrazine
Published in Baylor University Medical Center Proceedings, 2021
Madeline Frizzell, Nhan M. Nguyen, Sonal A. Parikh, Maya Sinai, Leonard Goldberg
Erythema multiforme is a self-limited, hypersensitivity eruption of sharply demarcated papules and plaques, which can have the characteristic targetoid appearance and typically cover <10% of body surface area.1,6,7 Many patients also exhibit mucosal involvement of the oral mucosa, conjunctiva, or genitals. Some experience burning or itching in the areas before lesions appear, but this is usually mild.6 The histopathology of the lesion can range from edema in the papillary layer with minimal to no epidermal involvement, found in erythematous papular lesions, to extensive keratinocyte necrosis resulting in subdermal bullae formation, found in the classical target lesions.1