Histopath

• The hypodermis (subcutaneous tissue) is the deepest layer of skin that attaches the skin to underlying structures and provides insulation and cushioning.
• The dermis is the thicker middle layer of skin that contains blood vessels, nerves, hair follicles, sweat glands, and sebaceous glands.
• The epidermis is the outermost layer of skin, consisting of stratified squamous epithelium.
• Skin appendages include hair follicles, sebaceous glands, sweat glands, and nails.
• Hair follicle - A tubular invagination of the epidermis containing a hair shaft surrounded by connective tissue sheaths.
• Sebaceous gland - An exocrine gland associated with hair follicles that secretes an oily substance called sebum into the hair canal.
• Skin has three layers: epidermis, dermis, and subcutaneous tissue.
• Skin color varies due to melanin pigmentation, which protects against UV radiation damage.
• Melanocytes produce melanin pigment granules.
• Epidermal cells are constantly being replaced by new ones from below.
• The epidermis is the outermost layer of skin composed of stratified squamous epithelium with five layers from bottom to top: basal cell layer, spinous cell layer, granular cell layer, clear cell layer, and cornified cell layer.
• Melanocytes are specialized cells found at the base of the epidermis that produce melanin.
• Hair follicles are tubular invaginations of the epidermis that contain hair shafts and produce new hairs through mitosis.
• Sebaceous glands are associated with hair follicles and produce an oily substance called sebum.
• Sebaceous gland - An exocrine gland associated with hair follicles that secretes an oily substance called sebum.
• Sweat gland - An exocrine gland found throughout the body that produces sweat as a response to heat or emotional stimuli.
• Sweat gland - An exocrine gland that produces sweat as part of thermoregulation.
• Nail - A hard keratinized structure covering the distal end of digits, protecting them from injury and providing sensory input.
• Epidermis consists of five layers (stratum basale, spinosum, granulosum, lucidum, corneum) and is composed mainly of keratinocytes.
• Nail - A hard keratinized structure covering the distal end of digits, protecting them from injury and providing tactile sensation.
• Sweat glands are coiled or straight ducts that open onto the surface of the skin and produce sweat as a response to heat and stress.
• Dermis is made up of collagen fibers arranged in bundles or sheets, elastic fibers, reticular fibers, and ground substance.
• Melanocyte - A pigment-producing cell located at the base of the epidermis responsible for producing melanin.
• The stratum corneum is composed of dead keratinized cells arranged in orthogonal rows.
• Melanocytes are specialized cells found in the basal layer of the epidermis responsible for producing melanin.
• Subcutaneous tissue is also known as hypodermis and is composed of loose areolar connective tissue.
• Stratum lucidum is present only in thick skin (palms/sol).
• The stratum basale is the deepest layer of the epidermis and contains stem cells.
• Dendritic cells are antigen-presenting immune cells located throughout the body's tissues.
• Dendritic cells are immune system cells involved in antigen presentation.
• Stratified squamous epithelium consists of multiple cell layers, including keratinized (dead) cells on top and living cells at the bottom.
• Basal cell layer (stratum basale) contains stem cells that divide mitotically to form new keratinocytes.
• Langerhans cells are a type of dendritic cell found in the epidermis and play a role in the immune response.
• Dense irregular connective tissue forms the papillary layer of the dermis.
• Langerhans cells are specialized dendritic cells present in the upper part of the epidermis.
• Spinous cell layer (stratum spinosum) consists of several rows of flattened cells connected by desmosomes.
• Keratinization involves the accumulation of dead cells filled with keratin protein fibers.
• Keratinocytes make up most of the epidermis and secrete keratin protein fibers.
• Nails are hardened keratinized tissue covering the distal ends of fingers and toes.
• Granular cell layer (stratum granulosum) contains keratohyalin granules involved in keratinization.