Hypothalamus and Reproduction

Not true of GnRH cells is

A. They originate from the neural crest and progenitors
B. Scattered in distribution
C. Bipolar in shape
D. The number of GnRH neurons is Very high in human

Hypothalamus is directly connected with the posterior lobe of the pituitary (neurohypophysis) by

A. Arcuate nucleus and Posterior hypothalamus nucleus
B. Supraoptic and paraventricular nuclei
C. Dorsomedial nucleus and mamillary body
D. Suprachiasmatic nucleus and preoptic area

Not true of tuber cinereum

A. Anteriorly continuous with the lamina terminalis
B. Referred to as the pituitary stalk
C. Constitutes nerve fibers traveling from the hypothalamus to the pituitary gland
D. Inferior distention of the floor of mammillary bodies

GnRH is secreted by

A. Arcuate nucleus of the hypothalamus
B. Supraoptic nucleus
C. Mamillary body
D. Suprachiasmatic nucleus

Not true of secretions from hypothalamus

A. TRH stimulates the release of thyrotropin and prolactin from the pituitary.
B. GnRH stimulates anterior pituitary for synthesis, storage and secretion of gonadotropins.
C. Corticotropin releasing hormone (CRH) is a tripeptide
D. Melanocytic releasing factor is secreted from hypothalamus

Gene for the GnRH precursor is located on –

A. Chromosome 6
B. Chromosome 7
C. Chromosome 8
D. Chromosome 9

GnRH formation is congenitally absent in

A. Down’s syndrome
B. Kallmann syndrome
C. Turner syndrome
D. Polycystic ovary syndrome

Which is used as a surrogate of GnRH pulsatility

A. FSH pulse frequency
B. LH pulse frequency
C. Estradiol pulse frequency
D. Oxytocin pulse frequency

In shorts

  • GnRH is secreted in the hypophysial portal bloodstream at the median eminence.
  • Median eminence -secretions of the hypothalamus collect at median eminence before entering the portal system and emptying into the general circulation
  • Elevated prolactin levels – decrease GnRH activity. 
  • Hyperinsulinemia – increases pulse activity leading to disorderly LH and FSH activity, [ seen in polycystic ovary syndrome].
  •  Kallmann syndrome – Defective GnRH migration leads to hypogonadotropic hypogonadism due to GnRH deficiency and anosmia 
  • Mutations in prokineticin genes (PROK1 and PROK2) lead to hypogonadotropic hypogonadism without anosmia.
  •  Stimulatory effects of GnRH on LH and FSH secretion are not identical. FSH secretion is more irregular than LH

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