Endocrine glands (cells)

1
Endocrine glands (cells)

• Hormone secreting cells or glands.
• May be in a form of scattered cells as
  enteroendocrine cells of GIT.OR in a form of
  gland as pituitary and thyroid glands.
• Endocrine glands have cells that arranged in
  columns or cords separated by fenestrated blood
  capillaries EXCEPT thyroid gland in which cells
  are arranged to form follicles.

2
Hypophysis (pituitary gland)

• Development of Hypophysis (pituitary gland)

3
Hypophsis (pituitary gland)

• It develops from 2 different tissues
• 1-Ectodermal epithelial tissue of the roof of
  the developing mouth---Rathkes pouch giving
  Adenohypophsis (Anterior pituitary).
• 2-Ectodermal neural tissue of dienchephalon----Neu
  rohypophsis (Posterior pituitary).
• Parts of hypophsis
• 1-Adenohypophysis
  2-Neurohypophysis
• a-Pars distalis.
  a-Pars nervosa.
• b-Pars tuberalis.
  b-Infundibulum.
• c-Pars intermedia. c-
  Median eminence.
• 
  

4
Blood supply and control of secretion

• Superior hypophseal arteries supply the pars
  tuberalis and the infundibulum and give primary
  capillary plexus in the median eminence.
• Inferior arteries supply the pars nervosa and
  send few branches to the ant. lobe
• The hypophseal portal system of veins delivers
  neurosecretory hormones from the primary
  capillary plexus of the median eminence to the
  secondary capillary plexus of the pars distalis.
• These hypothalamic hormones stimulate or inhibit
  the secretion of cells of pars distalis.

5
(No Transcript)
6
Pars nervosa (Neurohypophsis)

• Does not contain secretory cells.
• Does not contain cell bodies of neurons.
• Is rich in unmyelinated nerve axons.
• Is rich in fenestrated
• blood capillaries.
• Contains Herring bodies
• that contain vasopressin (ADH)
• oxytocin H. that are
• secreted by hypothalamus (.
• Contains supporting glial cells called
  pituicytes.

7
Adenohypophysis (anterior pituitary)

• Pars intermedia Contains cysts full of colloid
  lined with cuboidal epith.It may contain cords
  of basophils that secrete MSH.
• Pars tuberalis
• It surrounds the hypopheseal
• (neural)stalk of neurohypophysis
• Most of its cells are basophilic
• gonadotropic cells that arranged
• in cords separated by blood
• capillaries and portal system

8

• Pars distalis
• 1-Chromophobes Have no affinity to stain.
• Are small pale
  cells.
• 
  Undifferentiated cells.
• 2-Chromophils Have an affinity to the
  stain.
• They are 2 groups
• I-Acidophils include a- Somatotrophs
  that secrete somatotropin or growth H
• 
  b-Mammotrophs that secrete mammotropin or
  prolactin H.
• II-Basophils include a-Thyrotrophs that
  secrete TSH.
• 
  b-Corticotrophs that secrete ACTH.
• 
  c-Gonadotrophs that secrete 2 types of hormones
• -FSH
  in females it stimulates follicular maturation.
  In males it stimulate spermatogenesis.
• -LH in
  females it stimulates ovulation. In males it
  stimulate Lyedig cells(interstitial cells) to
  secrete testosterone.

9
Anterior pituitary (Adenohypophsis)
10
Medical application

• Pituitary benign tumors.
• Effects of pituitary Hormones on the mammary
  gland.
• Prolactin---stimulate milk formation.
• Oxytocin---stimulate milk ejection

11
Parathyroid glands

• They are 4 glands on the post.of thyroid gland.
• Each gland has its capsule and thin septae.
• The parenchyma is formed of chief cells, oxyphil
  cells, blood capillaries and adipose tissue (in
  adults).
• Chief cells are slightly eosinophilic, rich in
  rER and secrete parathyroid hormone (
  bl.calcium).
• Oxyphil cells are, arranged in groups or
  clusters, deep eosinophilic (rich in mitochondria
  and glycogen) and of unknown function
  (inactivated chief cells).

12
Thyroid parathyroid glands
13
Parathyroid gland
14
Ant. lobe of pituitary
Post. lobe of pituitary
15
Parathyroid gland
16
Thyroid gland

• Is covered by CT.capsule that
• sends septae to divide it into lobules.
• Its parenchyma is formed of
• follicles that are separated
• by reticular fibers, parafollicular
• cells and fenestrated blood capillaries.
• The follicles are formed of follicular cells
  (squamous to columnar) contain colloid.
• Follicular cells are basophilic, and rich in RER,
  mitochondria and apically located lysosomes.
• Parafollicular cells secrete calcitonin
  (decreases Bl.Calcium level).

17
Thyroid follicles and parafollicular cells (clear
cells)
Parafollicularcell
Follicular cells
18
Suprarenal (adrenal) glands

• It has a thick capsule that sends septae.
• Suprarenal cortex (80 of the gland) produces
  mineralocorticoids, glucocorticoids (cortisol and
  corticosterone), and androgens.
• The cortex is regulated by ACTH of ant. Pituitary
  and angiotensin II.
• Suprarenal medulla produces epinephrine and
  norepinephrine and is regulated by the
  sympathetic nervous system.
• The cortex is rich in fenestrated (without
  diaphragm) sinusoidal capillaries.
• The medulla receives a dual blood supply a. from
  cortical arteries and b. from cortical capillary
  beds.

19
Adrenal gland
It is formed of I. Cortex that is composed
of A-Zona glomerulosa. B-Zona fasiculata. C-Zona
reticularis. II.Medulla
20
Adrenal gland
21
Adrenal cortex zona glomerulosa
Is formed of cords and clusters of small
columnar cells that are rich in SER and
mitochondria. Produces Aldosterone hormone that
affect renal distal tubules.
22
Adrenal cortex zona fasiculata (spongiocytes)
It is the intermediate and the largest layer of
the cortex. It is formed of columns of large
polyhedral cells that are separated by
longitudinal sinusoidal capillaries. It cells
are rich in lipids so they appear empty
(spongiocytes). Its cells are rich in
mitochondria (tubular cristae),SER and lipofucin
pigment. Its cells secrete glucocoticoids. It
is regulated by ACTH of pituitary.
23
Adrenal cortexzona reticularis.
It is the innermost layer of adrenal cortex. It
is formed of anastomosing cords of deep
acidophilic cells. Its cells contains few
lipofucin and lipid droplets. The cells secrete
androgens.
24
Medulla of adrenal gland

• It the central portion of the adrenal gland.
• It is completely invested with adrenal cortex
  (not separated from it by CT. septa)
• It is formed of
• Chromaffin cells that contains granules of
  catecholamine as that of sympathetic NS.(They
  produce epinephrine and norepinephrine). They
  stain deep brown with chromic salts.
• Sympathetic ganglion cells scattered in CT. Relay
  on chromaffin cells.

25
(No Transcript)
26
Adrenal gland Thyroid gland