TLDR As sheep age, their hair fibers and follicles grow larger and more organized, with no significant differences between males and females.
The study examined the histological characteristics of hair fibers and follicles in Iranian native Bakhtiari sheep across different age groups and sexes. Skin samples from 24 sheep (12 males and 12 females) were collected from eight body regions and analyzed. The findings indicated that while the general histological features were similar to other breeds, there were some differences. All hair fibers had a medulla, and follicles were associated with structures like sweat and sebaceous glands. No significant differences were found between sexes, but with increasing age, fibers and follicles became larger and more organized.
57 citations,
August 1997 in “Microscopy Research and Technique” New molecules involved in skin and hair growth were identified, improving understanding and future treatments.
6 citations,
June 2013 in “British Journal of Dermatology” Intense pulsed light treatment mainly damages pigmented hair parts but spares stem cells, allowing hair to regrow.
January 2011 in “Medical Journal of National Defending Forces in Northwest China” 
30 citations,
May 2010 in “British Journal of Dermatology” Intermediate hair follicles are a better model for studying hair growth and testing hair loss treatments.
3 citations,
April 2010 in “Endocrinology” The mouse model suggests male pattern baldness may be due to an enzyme increasing DHT and higher androgen receptor levels in hair follicles.
321 citations,
December 2009 in “Journal of Dermatological Science” Dermal cells are key in controlling hair growth and could potentially be used in hair loss treatments, but more research is needed to improve hair regeneration methods.
January 2009 in “Chinese Journal of Aesthetic Medicine” January 2003 in “Chinese Journal of Reparative and Reconstructive Surgery” Dermal papilla cells can help form hair follicles and produce hair.
66 citations,
August 2001 in “Experimental Dermatology” Human hair follicle cells can grow hair when put into mouse skin if they stay in contact with mouse cells.
57 citations,
November 1998 in “Wound Repair and Regeneration” Hair papilla cells can create and regenerate hair bulbs under the right conditions.
