Histochemically demonstrable glycogen may be found in the human epidermis when the level of glycogen is above 400 to 500 mμg/mg of fresh tissue, and it may be found normally in the malpighian cells of the epidermis. Seven to 12 hours after ultraviolet light irradiation glycogen accumulates in the malpighian cells, reaches a peak at 24 hours, and may persist for at least 18 days. Increases in malpighian cell glycogen may also be found in nonexposed areas after ultraviolet irradiation.
Basal cell glycogen is not found in normal epidermis nor does it appear in nonexposed areas after ultraviolet irradiation. In exposed areas it appears 4½ hours after irradiation, reaches a peak at 7½ to 12 hours, and disappears by 24 to 44 hours.
Changes in the activities of the enzymes glycogen synthetase and phosphorylase do not correlate with the changes in epidermal glycogen content.
Ohkawara A, Halprin KM. Ultraviolet Light and Glycogen Formation in the Human Epidermis. Arch Dermatol. 1967;95(4):416-421. doi:10.1001/archderm.1967.01600340076018