Epidermis : Basic Structure and Function
Contents
Not true of Merkel cell is
A. Located directly above the basement membrane zone
B. Contain intracytoplasmic neurosecretory-like granules
C. Have direct connections with adjacent Langerhans cells
D. Can be found in the basal layer of the palms and soles
All are true regarding keratinocytes except
A. Keratinocytes are squamous cells
B. Keratin mutations are recognized causes of skin disease
C. Horn cells are the result of a degradative process of terminal keratinization
D. Odland bodies appear in premature keratinocytes
Not true of melanocytes is
A. Racial differences in skin color are caused by differences in the number of melanocytes
B. Melanocyte is a dendritic cell
C. Melanosomes are synthesized in the Golgi zone of the cell
D. Nevi are benign proliferation of melanocytes
All are true of Langerhans cells in skin except
A. Langerhans cells are normally found in the stratum spinosum.
B. Unlike melanocytes, Langerhans cells are connected to adjacent keratinocytes by the desmosomes
C. Langerhans cells are difficult to detect in routinely stained sections except in sections impregnated with gold chloride
D. Birbeck granules are distinct intracytoplasmic granules in Langerhans cells.
Not true of function of skin cells
A. Langerhans cells function primarily as immune recognition cells
B. Functions of Melanocytes is principally in a photoprotective role
C. Merkel cells primarily label for neuroendocrine markers
D. Keratinocytes are critical for normal functioning of the epidermis
In short
The Merkel cell is found in the basal layer of the palms and soles, oral and genital mucosa, nail bed, and follicular infundibula. They label for neuroendocrine markers such as chromogranin and synaptophysin.
Slow-cycling stem cells provide a reservoir for regeneration of the epidermis. Sites rich in stem
cells include the deepest portions of the rete, especially on palmoplantar skin, as well as the hair bulge.
Glycolipids such as ceramides contribute a water-barrier function to skin and are typically found in topical products meant to restore the epidermal barrier.
Melanocytes and keratinocytes express neurotrophins (ectodermal nerve growth
factors).
