Sunday, July 17, 2011


Hormones responsible for growth are sexually dimorphic
Yes, the statement is correct.
Sexual dimorphism means difference in forms between males and females of the same species. In animals that have separate sexes, males and females will always different, but in highly dimorphic species,2 sexes look very different and are often quite unequal in size.
Sex differences in the pattern of circulating somatotropin (ST) and circulating concentration of IGF (insulin like growth factor) and IGF-binding protein were demonstrated in rapidly growing prepupertal animals.The differences are consistent with the hypothesis that the somatotropic axis is a mechanism mediating sex differences in growth.Differences in circulating pattern of these hormones may arise from the actions of steroids during sexual differentiation and before puberty.
Several hypothalamic nuclei are sexually dimorphic i.e. there are clear difference in both structure and function between males and females. Some differences are apparent even in gross neuroanatomy.most notable is the sexually dimorphic nuclei within the preoptic area which is larger in males.(greater cell number and larger cell size in males).However most of the differences are subtle changes in the connectivity and chemical sensitivity of particular sets of hormones. The importance of these changes can be recognised by functional difference between males and females. For example secretion of GH is sexually dimorphic and this is one reason why in many species, adult males are much larger than females. and estrogens sensitive neuron in hypothalamus is sexually dimorphic.

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