Dr Archana Rani Associate Professor Department of Anatomy KGMU UP Lucknow 272015 Introduction Endocrine tissue is made up of cells that produce secretions which are poured directly into blood ID: 192071
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Slide1
Histology of the Endocrine Glands
Dr. Archana RaniAssociate ProfessorDepartment of Anatomy,KGMU UP, Lucknow
2.7.2015Slide2
Introduction
Endocrine tissue is made up of cells that produce secretions which are poured directly into blood.Endocrine cells lie in close apposition to blood capillaries or sinusoids.Secretions of endocrine cells are called hormones.Hormones travel through blood to target cells and influence their function.Slide3
The Endocrine Glands(Ductless glands)
Pituitary (hypophysis)Anterior pituitary
Posterior pituitary
Adrenal gland (suprarenal)
Adrenal cortex
Adrenal medulla
Thyroid gland
Follicles
Parafollicular
cells
Parathyroid glandSlide4
The Pituitary Gland
(Hypophysis Cerebri)
aSlide5
The Pituitary Gland
(Hypophysis Cerebri)
“Master endocrine gland
”.
Parts:
Adenohypophysis
(Anterior Pituitary): consist of pars
distalis
, pars
intermedia
& pars tuberalis. Neurohypophysis (Posterior Pituitary): consist of pars nervosa, infundibular stalk & median eminence.Slide6
Adenohypophysis
Pars Distalis:Cells are arranged as irregular cords in between thin-walled fenestrated sinusoids.Consists of 2 major group of cells: chromophils & chromophobes.
Chromophils
are of 2 types:
basophils
&
acidophils
.
Pars
Intermedia
:
Poorly developed in humans.Consists mainly of basophils.Presence of colloid filled vesicles.Some cells produce melanocyte stimulating hormone (MSH).Pars Tuberalis:Consists of chromophilic (mostly basophilic) & chromophobic cells.Slide7
Neurohypophysis
Consists of: Numerous non-myelinated nerve fibresSupporting cells (pituicytes)SinusoidsProduce 2 hormones:
Oxytocin
Vasopressin
Herring bodies:
collection of
secretory
granules at the terminal portion of axonal processing.Slide8
Posterior PituitarySlide9
Hypophysis
(Mallory-Azan & orange G. stain)Slide10
Cells and hormones of the anterior pituitary
LM staining
Cell type
Hormone
Releasing (+) or
inhibiting (-) horm.
Acidophil
Somatotrophs
Growth hormone (GH)
= somatotropin
GHRH (+)
Somatostatin (-)
Acidophil
Mammotrophs
=
lactotrophs
Prolactin (PRL)
[Dopamine (-)
estrogen (+)]
Basophil
Thyrotrophs
Thyroid stimulating hormone (TSH)
= thyrotropin
TRH (+)
Basophil
Gonadotrophs
Luteinizing hormone (LH), follicle stimulating hormone (FSH); both = gonadotropinGnRH (+)Basophil(human)CorticotrophsAdrenocorticotropin(ACTH) = corticotropinCRH (+)Slide11
Hypophysis (H&E stain)Slide12
Pars
distalis (Azan stain)Slide13
Pituitary glandSlide14
Anterior pituitary (trichrome stain)Slide15
Anterior pituitary (H&E stain)
BasophilSlide16
Posterior Pituitary
HormonesAntidiuretic hormone (ADH = arginine
vasopressin)
Oxytocin
Neurosecretion
Hormones synthesized as part of larger proteins (
neurophysins
) in neuron cell bodies of hypothalamus.
Transported in axons to pars nervosa (hormone cleaved from
neurophysin
).
Hormone secreted from axon terminals into capillaries.
Pituicytes
Specialized
glia
of pars nervosa.Slide17
Pars
intermedia, between anterior and posterior pituitary (Poorly developed and of doubtful function in humans)
Intermedia
Anterior
PosteriorSlide18
Pars
intermedia (rat pituitary)
Rathke's pouchSlide19
THYROID GLANDSlide20
Microscopic structure
The gland is surrounded by a thin fibrous capsule.Septa from the capsule extend into the gland & divide it into lobules.Lobules are made up of spherical masses called follicles.Follicle has a cavity filled with homogenous material called colloid
.
Follicular cells are normally
cuboidal
in shape.
Secrete 2 hormones: tri-
iodothyronine
(T3) & tetra-
iodothyronine
(T4) or
thyroxine
.Slide21
Microscopic structure (contd…..)
Parafollicular cells (C-cells):Embedded within a follicle or lie between follicles.Singly or in groups.Cells are polyhedral with oval eccentric nucleus and cytoplasm contains secretory granules.Light staining cells.
Secrete hormone
calcitonin
. Slide22Slide23
Parathyroid Gland
Small ovoid bodies (4 in no.) embedded in the connective tissue capsule on the posterior surface of thyroid gland.Consists of 2 types of cells:Chief cells (principal cells): more numerous, polygonal, round centrally located nucleus & mildly eosinophilic cytoplasm, secrete p
arathyroid hormone (PTH).
Oxyphil
cells:
larger in shape, deep acidophilic cytoplasm.Slide24
Parathyroid Gland (H&E stain)Slide25
Adrenal Gland(Suprarenal Gland)Slide26
Microscopic structure (low power)
capsule
cortex
medulla
The gland is covered by connective tissue capsule.
Capsule sends septa inside the gland.
2 parts:
Cortex
MedullaSlide27
Microscopic structure (low power)
Zona glomerulosa
Zona fasciculata
Zona
reticularis
Mineralocorticoid
(
aldosterone
)
Glucocorticoids
(
cortisol
)
Androgen
(
dehydroepiandrosterone
) & Estrogen
Medulla
Cortex
Catecholamines
(epinephrine &
norepinephrine
)Slide28
Adrenal Cortex
3 layers:Zona Glomerulosa: cells are arranged as rounded clusters separated by thin connective tissue. Cells are columnar with dark staining nuclei and acidophilic cytoplasm.Zona Fasciculata
:
thick zone, large pale staining polyhedral cells arranged into parallel columns 1-2 cell thick.
Zona
Reticularis
:
small rounded deep staining cells arranged in branching &
anastomosing
cords.Slide29Slide30
Adrenal Medulla
Cells are large, epitheloid & arranged in groups.Cells are closely related to sinusoidal capillaries.Cytoplasm is light basophilic with H&E stain.Chromaffin reaction: Tissue fixation with potassium
bichromate
shows fine brown granules in the cells of medulla.
Cortex
Medulla
CapsuleSlide31
References
1. diFiore’s Atlas of Histology with functional Correlations, 12th Edition.
2. Textbook of Human Histology.
Inderbir
Singh, 1
st
Edition.
3. Textbook of Histology. GP Pal, 3
rd
Edition.Slide32
MCQ
Q1. The supportive cells in pars nervosa are known as:
a.
Chromophils
b.
Chromophobes
c. Herring bodies
d.
PituicytesSlide33
MCQ
Q2. Parafollicular cells is a specific feature of:a. Pituitary
b. Thyroid
c. Parathyroid
d. SuprarenalSlide34
MCQ
Q3. The epithelial lining of thyroid follicles in resting phase is:
Squamous
Cuboidal
Columnar
TransitionalSlide35
MCQ
Q4. Increased amount of lipid droplets are found in cells of which zone of adrenal gland?a. Zona glomerulosa
b.
Zona
fasciculata
c.
Zona
reticularis
d. All of the aboveSlide36
MCQ
Q5. Chromaffin reaction is depicted by which endocrine gland?a. Pituitary
b. Thyroid
c. Parathyroid
d. Suprarenal