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Pituitary Histology

Adenohypophysis

  • glandular epithelial tissue
  • develops from upward evagination of oropharynx (Rathke's pouch)
  • pars distalis
    • bulk of adenohypophysis
    • arises from anterior wall of Rathke's pouch
    • adrenocorticolipotrophs (most common basophils) secrete ACTH and LPH
    • gonadotrophs (small basophils) secrete LH and FSH
    • thyrotrophs (large basophils) secrete TSH
    • somatotrophs (most common, small acidophils) secrete somatostatin
    • lactotrophs or mammotropes (variable and scattered) produce prolactin and LTH
  • pars intermedia
    • thin remnant of posterior wall of Rathke's pouch
    • abuts neurohypophysis
  • pars tuberalis
    • forms from lateral walls of pouch and forms collar around pars intermedia

Neurohypophysis

  • pars nervosa
    • contains neurosecretory nerve endings
  • infundibulum
    • contains axons of neurosecretory neurons
  • pituitocytes are supporting cells of axons in neurohypophysis

Blood supply

Hypothalamo-Hypophysial Portal Vessels

  • blood supply from superior hypohyseal arteries to pars tuberalis, median eminence and infundibular stem
  • blood supply from inferior hypophyseal arteries to pars nervosa
  • most of anterior pituitary supplied by portal veins

14.2.1 Components of Pituitary and Neurendocrine Hypothalamus

development of pituitary gland
concept of neurosecretion; concept of feedback regulation at hypothalamic and pituitary levels
gross and microscopic structure of pituitary and component parts: adenohypophysis, neurohypophysis
neurohypophysis: nerve endings of hypothalamic neurosecretory neurons
adenohypophysis: endocrine cells. Anterior part. Tuberal and intermediate (vstigial) parts. Folliculo-stellate cells, pituitary macrophages.
cell types: somatotrophs, lactotrophs, gonadotrophs, thyrotrophs, corticotrophs
control of adenohypophysis: (a) by CNS: neurosecretion from hypothalamus via hypothalamo-hypophysial portal vessels; (b) by negative feedback of target hormones and effects