THE ENDOCRINE SYSTEM AND HAIR GROWTH IN THE RAT

The study investigated the impact of endocrine factors on hair growth in albino rats, revealing that hair growth rate was not influenced by depilation methods or history. Male rats exhibited faster hair growth than females, but castrated males and ovariectomized females matched the growth rate of intact males. Thyroidectomized female rats had reduced hair growth, while androgens had no effect. Oestrogens slowed hair growth, particularly in males. Female rats responded to crude saline extracts of female rat pituitary glands with increased hair growth, an effect not seen with acetone-dried material or in male rats. Other substances, including progesterone, desoxycorticosterone acetate, thyroxin, and various animal pituitary extracts, showed no impact on hair growth. The study concludes that hair growth in normal rats, especially males, cannot be significantly accelerated beyond its natural rate, and the female response to pituitary extract may counteract the inhibitory influence of endogenous oestrogens.