Histology Flashcards
What is the uppermost layer of the skin called and what is it made of?
Epidermis and is made of stratified squamous epithelium
What is the layer beneath the epidermis and what is it made of?
Dermis and consists of connective tissue.
What is the main type of cell within the epidermis?
Keratinocytes
What cells are located in the epidermis (other than keratinocytes)?
Merkel cells, langerhan’s cells and melanocytes.
What are Merkel cells?
Myelinated mechanoreceptors that reach out to interact with cells and transmit pressure/touch.
What are Langerhan’s cells?
They are dendritic cells of the epidermis. They originate from the bone marrow and are antigen presenting cells. Responsible for detecting microbes.
What are melanocytes?
They are pigment producing dendritic cells. Their function is to produce and secrete melanin in order to protect the adjacent keratinocytes.
What is stored in the sub-cutis?
Energy is stored in the sub-cutaneous fat.
What are the layers of the epidermis?
Keratin layer (stratum corneum)
Granular layer (stratum granulosum)
Prickle cell layer (stratum spinosum)
Basal layer (stratum basale)
What are defining features of each of the epidermal layers?
Keratin layer - consists of corneocytes, these are non-nucleated cell remnants. Consists of 80% keratin and filaggrin. Forms a tight waterproof barrier.
Granular layer - consists of 2 to 3 flatter cells. Odland (or lamellar bodies) are contained within the granular layer, these are processing areas for lipids within keratinocytes.
Prickle cell layer - consists of large polyhedral cells and lots of desmosomes. Intermediate filaments connect to the desmosomes.
Basal layer - consists of small cuboidal cells and is 1 cell thick. Contains a lot of keratin and is highly metabolically active.
What are Blaschko’s lines?
The developmental growth pattern of the skin, they don’t follow vessels, nerves or lymphatics. Diseases in embryo/foetal development will follow these lines.
What is the characteristic feature of merkel cells in histogram?
Birbeck granules - tennis racquet appearance
