TLDR K14 expression in young rats differs from adults.
The study investigated the hair cycle and keratin 14 mRNA (K14 mRNA) distribution in the skin and hair follicles of 69 neonatal and postnatal Wistar rats. It was found that the first hair cycle was significantly shorter than the second. K14 expression was primarily localized in the keratinizing epidermal cells of the stratum basal/spinosum, hair follicles, and some sebaceous gland cells, with no positive signals in other cell types or regions. The study concluded that K14 expression in newborn and juvenile rats differed from that in adults or human embryos.
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,
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,
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,
November 2013 in “International Journal of Radiation Biology” Gamma-rays exposure during the resting phase of hair growth can damage hair regeneration and color in mice.
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January 2010 in “Chinese journal of clinical anatomy” Hair follicles in C57BL/6 mice develop rapidly from late embryonic stages to shortly after birth, with key growth and regeneration phases identified.
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,
August 2000 in “Journal of Investigative Dermatology” April 2000 in “Chinese Journal of Dermatology” 
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,
May 1998 in “Journal of Dermatological Science” Insulin or IGF-I is needed for hair growth in newborn mice, while minoxidil helps adult mouse hair grow, suggesting a way to study human hair loss.