<prompt> Hypothalamopituitary axis becomes active and functional at:20th week of gestation5th year of life5th week of life5th month of life  <response>: Ans. a 20th week of gestation. Ref. Nelsons textbook of Paediatrics 17th ed. 1870 Hypothalamic neurons synthesize TRH by 6-8 weeks of gestation and TSH secretion is evident by 12th week of gestation. Maturation of HP-thyroid axis occurs by 2nd half of gestation. Feedback relationships by 3 months postnatally.- Fetal thyroid bilobed shape is recognised by 7th week of gestation- Thyroid folicle cell and colloid formation seen by 10th week- Thyroglobulin synthesis occurs from 4th week- T4, T3 synthesis and secretion from 12th week of gestationThe CNS-hypothalamic-pituitary-gonadal-target organ axisOvarian hormones have direct and indirect effects on other tissues e.g., bone, skin, muscle. FSH follicle-stimulating hormone; GnRH gonadotropin-releasing hormone; LH luteinizing hormone. 