Anatomy, physiology, and histology of the skin
Michael Parker, Charlie James in 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.
Actions of Dopamine on the Skin and the Skeleton
Nira Ben-Jonathan in Dopamine, 2020
Structures within the dermis include Excretory and secretory glands (sebaceous, eccrine, and apocrine). Sebaceous glands secrete triglyceride and cholesterol-rich sebum that lubricate the skin and keep it supple and waterproof. They are often associated with hair shafts.Hair follicles and nails. The hair follicle provides a protective niche to several stem cell populations in the skin, including keratinocyte stem cells, melanocyte stem cells, a population of epidermal neural crest stem cells, and the dermal stem cell compartment, the dermal papilla. These stem cells are most active during wound healing.Sensory nerve receptors of Merkel and Meissner’s corpuscles (touch receptors), Pacinian corpuscles (pressure receptors), and Ruffini corpuscles (mechanoreceptors). Fingerlike projections within the papillary region of the dermis extend toward the epidermis. The thick reticular region has collagenous, elastic, and reticular fibers.
Skin Morphology, Development and Physiology
Heather A.E. Benson, Michael S. Roberts, Vânia Rodrigues Leite-Silva, Kenneth A. Walters in Cosmetic Formulation, 2019
The dermis, a critical component of the body, not only provides the nutritive, immune and other support systems for the epidermis through a thin papillary layer adjacent to the epidermis but also plays a role in temperature, pressure and pain regulation. The dermis is about 0.1 to 0.5 cm thick and consists of collagenous fibres (70%), providing a scaffold of support and cushioning, and elastic connective tissue, providing elasticity, in a semi-gel matrix of mucopolysaccharides. In general, the dermis has a sparse cell population. The main cells present are the fibroblasts, which produce the connective tissue components of collagen, laminin, fibronectin and vitronectin; mast cells, which are involved in the immune and inflammatory responses; telocytes, which may be involved with skin regeneration and repair (Ceafalen et al., 2012; Kang et al., 2015); and melanocytes involved in the production of the pigment melanin.
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].
Laser treatment for facial acne scars: A review
Published in Journal of Cosmetic and Laser Therapy, 2018
Neil S. Sadick, Andrea Cardona
Nonablative laser systems are also frequently used to treat atrophic acne scars. They emit wavelengths in the visible or in the infrared (IR) range, resulting in stimulation of type I and III collagen and elastic fibers (41). One benefit of nonablative lasers is that they deliver energy into the dermis without destroying the overlying epidermis resulting in less side effects and shorter recovery times. However, clinical improvement may be moderate, especially for deeper ice-pick and boxcar scars, and patients may require multiple treatment sessions (14). Cooling devices are often incorporated in these lasers to reduce patient discomfort and ensure that the epidermis is protected while the upper papillary dermis is stimulated for collagen production. Aside from matrix remodeling, some nonablative lasers are utilized to clear pigment and erythema in atrophic scars. The treatment of erythema and pigment in acne scars is an important and often the first component of treatment to be addressed, as coloration accentuates acne scars and makes them more noticeable to the observer. Reducing coloration can improve the appearance of acne scars even without improvement in the more difficult to correct textural abnormalities.
Skin proteomics – analysis of the extracellular matrix in health and disease
Published in Expert Review of Proteomics, 2020
Jörn Dengjel, Leena Bruckner-Tuderman, Alexander Nyström
The second important skin layer is the dermis (Figure 1). It provides tensile strength, elasticity, and resilience to the skin. Histologically the dermis can be divided into a thin superficial layer, the papillary dermis, and a thicker deeper layer, the reticular dermis. Although adnexal, vascular, lymphatic and neural structures traverse the dermis, fibroblasts constitute the major cell population embedded in the dermal connective tissue. These are ECM producing mesenchymal cells responsible for maintenance, repair, and regeneration of the dermis. Recent research data indicate that the superficial, middle, and deeper dermal layers harbor distinct fibroblast subpopulations [62], nevertheless definitive cell markers still remain elusive and functional characteristics that distinguish them are not fully understood. Quantitatively minor and changing cell populations in the dermis encompass immune cells. Upon need, they migrate into the skin and exert decisive functions in immune response, inflammation, and regenerative processes [63].
Related Knowledge Centers
- Basement Membrane
- Collagen
- Elastic Fiber
- Epidermis
- Mechanoreceptor
- Skin
- Subcutaneous Tissue
- Cutis
- Dense Irregular Connective Tissue
- Ground Substance