Follicular extrusion

Tretinoin (a retinoid topical vitamin A acid) is a comedolytic agent that increases cell turnover in the follicular wall and decreases cohesiveness of cells, leading to extrusion of comedones and inhibition of new comedo formation. It also decreases the number of cell layers in the stratum corneum from about 14 to about five. 

Tretinoin is a retinoid, which decreases cohesiveness and stimulates mitotic activity and turnover of follicular epithelial cells, resulting in decreased formation and increased extrusion of comedones. PO induces maturation of acute promyelocytic leukemia cells followed by a repopulation of the bone marrow and peripheral blood by normal, polyclonal hematopoietic cells in patients achieving complete... 

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