ENDOCRINE GLANDS
Dr Iram Tassaduq
ADRENAL (SUPRARENAL ) GLAND
• Lies on upper pole of
each kidney
• Comprised of two zones
outer cortex
inner medulla
• Develops from
intermediate mesoderm
and neural crest cells
INTRODUCTION
• The adrenal gland is
encased in a connective
tissue capsule that
extends septae into the
substance of the gland.
The organ is richly
vascularized and capsular
blood vessels, nerves and
lymphatics penetrate
along with the connective
tissue septae.
CORTEX
• zona glomerulosa - thin,
outermost zone
• zona fasiculata - thick,
middle zone
• zona reticularis - thin,
inner zone
ZONA GLOMERULOSA
• Composed of columnar
or pyramidal cells
arranged as rounded or
arched cords
• Occupy 15% of gland
volume
ZONA GLOMERULOSA
ZONA FASICULATA
• Cells are arranged in
straight cords. 1-2 cells
thick
• Cords run at right
angles to the surface of
organ and have
capillaries between
them
• Occupy 65% of gland
volume
ZONA FASICULATA
ZONA RETICULARIS
• Polyhedral cells with
lipid droplets
• Form 7% of gland
• Appears vacuolated in
histological
preparations
• Cells are smallest in size
ZONA RETICULARIS
ADRENAL MEDULLA
• Composed of cords or clumps of cells called
chromaffin cells. These can acquire brown
colour which is due to oxidation of
catecholamines
• Modified postganglionic sympathetic neurons
ADRENAL MEDULLA
FUNCTIONS OF ADRENAL GLAND
THYROID GLAND
• C.T. sheath formed
by deep cervical
fascia
• Extremely labile
gland & varies in
size & structure
Three dimensional view of thyroid follicles
DEVELOPMENT OF THYROID
GLAND
• Begins to develop during 4th week of
gestation from a primordium
originating as an endodermal
thickening of floor of primitive
pharynx
STRUCTURAL UNIT OF THYROID
GLAND ----- THYROID FOLLICLE
FOLLICULAR EPITHELIUM
Follicular cells
Para follicular
cells
FOLLICULAR CELLS
PRINCIPAL/ CHIEF CELLS
• Responsible for the
production of T3 & T4
• Vary in size & shape
• Slightly basophilic in
H & E stained slides
• Lipid droplets
COLLOID
• Inactive storage form of
thyroid hormone
• Constituents
• Principal component is
thyroglobulin (large
iodinated glycoprotein)
• Enzymes
• Glycoproteins
• Staining with both acidic
& basic dyes. Strongly
with PAS
PARAFOLLICULAR CELLS
C CELLS/ CALCITONIN CELLS
Located in periphery of
follicular epithelium
No exposure to lumen
 In H & E stained slides
appear as pale staining
cells
Secrete calcitonin
FUNCTION OF THYROID GLAND
PARATHYROID GLAND
• Two pairs in mammals
• Embedded within
thyroid gland substance
• C.T. capsule is thin
PRINCIPAL CELLS/ CHIEF CELLS
• More numerous of
parenchymal cells
• Small, polyhedral cells,
of 7-10 um in diameter
• Rounded, vesicular
nuclei
• Responsible for
secretion of PTH
chief cells
OXYPHILL CELLS
• Constitute a minor
portion of parenchyma
• Found singly or in
clusters
• More rounded & larger
than principal cells
• Distinctly acidophilic
cytoplasm
• No secretory activity