Development and Structure of the Epidermis Flashcards
histological description of the epidermis
stratified squamous epithelium that contains keratinocytes
what type of tissue is the dermis
connective tissue
describe generally how the epidermis is formed embryologically
ectodermal cells form a single layer called the periderm, there is a gradual increase in cell layers and the periderm falls off
what layer is the dermis derived from
mesoderm
where do melanocytes originate
neural crest
what are the layers of foetal skin at 4 weeks (superficial to deep)
periderm -> basal layer -> dermis
what are the layers of foetal skin at 16 weeks (superficial to deep)
keratin layer -> granular layer -> prickle cell layer -> basal layer -> dermis
melanocytes migrate from the neural crest
when is skin development complete
26 weeks
what are the appendages of the skin
nails, hair, glands, mucosae
where are there 5 layers of the epidermis and what is this 5th layer called and where is it
palms and soles
stratum lucidum - between the keratin and granular layers
what other cell types are present in the epidermis
melanocytes, Langerhans cells and Merkel cells
what are the 4 epidermal layers from superficial to deep
keratin layer
granular layer
prickle cell layer
basal layer
what controls epidermal turnover
growth factors, hormones, cell death
describe the differentiation of keratinocytes
migrate from the basement membrane and continually regenerate the epidermis
takes roughly 28 days
describe the basal layer
1 cell thick, small cuboidal keratinocyte stem precursors many intermediate filaments very metabolically active - constantly undergoing mitosis anchored to dermis by basement membrane
