Answer:
Vitamin D3 is synthesized in keratinocytes of the two epidarmal layers namely stratum basale (bottom layer) and stratum spinosum.
Explanation:
In the two epidermal layers of the skin namely stratum basale and stratum spinosum, 7-dehydrocholesterol (pro-vitamin D3) is converted to vitamin D3. This process takes place in the presence of ultravoilet radiations. Briefly, upon exposure, the pro-vitamin D3 is photolyzed to pre-vitamin D3. The pre-vitamin D3 then isomerized to form vitamin D3.
