Chemical Coordination and Regulation Question 68
68. MSH of pars intermedia of middle pituitary is responsible for
[1988]
(a) darkening of skin in lower vertebrates
(b) light colouration of skin in lower vertebrates
(c) noth A and B
(d) darkening of skin in human beings
Show Answer
Answer : a
Hints & Solutions
(a) Melanocyte-stimulating hormone (MSH) or Melanotropin is secreted by the intermediate lobe of adenohypophysis (pars intermedia) of pituitary gland in mammals (other than man) so named ‘intermedin’. In lower vertebrates, it targets chromatophores & does wider distribution of the melanin grannules in chromatophores, so that the skin colour darkens. In birds & human beings and other mammals its role is uncertain but in man it is probably responsible for bronzing of skin, moles etc. Growth and sexual maturation are mainly controlled by the growth hormone (GH)insulin-like growth factor-1 (IGF-1) and hypothalamic-pituitary-gonadal (HPG) axes.
