endocrine system histo Flashcards
Responsible for the synthesis and secretion of chemical messenger
endocrine glands
composed of islands of secretory cells of epithelial origin derived from any of the 3 primary germ layers.
endocrine glands
It has supporting tissues rich in blood and lymphatic capillaries
Ductless glands
endocrine glands
Hypophysis cerebri
A specialized appendage of the brain which secretes a variety of hormones.
Pituitary gland
is a small, slightly elongated organ buried in the sella turcica and is covered by the diaphragm sellae.
Pituitary gland
divides pituitary gland into anterior and posterior
residual lumen of Rathke’s pouch
anterior pituitary gland
(adenohypophysis / pars distalis)
posterior pituitary gland
(neurohypophysis / pars nervosa)
this vestigial cleft divides the anterior pituitary from the pars intermedia.
residual lumen of Rathke’s pouch
An extension of the adenohypophysis surrounding the neural stalk
(PARS TUBERALIS.)
The anterior pituitary arises from
the RATHKE’S POUCH
parts/pars of Anterior lobe :
1) pars distalis
2) pars tuberalis
parts Posterior lobe :
1) pars intermedia
2) pars nervosa
Located between the pars distalis and pars nervosa
Composed of a thin layer of cells and vesicles containing acidophilic colloidal substance
Parenchymal cells are known as MELANOTROPHES
pars intermedia
1) Hormones which act directly on non-endocrine tissues:
a) GH b) prolactin c) ADH d) oxytocin e) MSH
Hormones which modulates the secretory activities of other endocrine glands (TROPHIC HORMONES):
a) TSH b) ACTH c) FSH d) LH
Hormones which modulates the secretory activities of other endocrine glands
TROPHIC HORMONES
——– may be described as pituitary-dependent endocrine glands
The thyroid, adrenal cortex and gonads
WAYS OF CONTROL OF PITUITARY SECRETIONS
Releasing Factors
Feedback Mechanism
The anterior lobe constitutes how many percent of the pituitary gland.
75%
The parenchyma(pars distalis) is made up of separated from sinusoidal capillaries by a small amount of reticular fibers.
anastomosing cords and clusters of epithelial cells
Endocrine organs
- Pituitary Gland
- Thyroid Gland
- Parathyroid gland
- Adernal Gland
- Paraganglia
- Pancreas
anterior lobe
made up of secretory cells derived from Rathke’s pouch, an embrologic extension of the primitive oral cavity.
adenohypophysis
the posterior lobe
is composed of neural tissue; it is a direct extension of the brain, and is attached to the hypothalamus by the pituitary stalk.
neurohypophysis
composed of round to polygonal epithelial cells arranged in cords and nests, amid a rich fibrovascular network. These cells release their granules in response to releasing factors elaborated in the hypothalamus.
pars distalis
types of parenchymal cells based on staining reactions:
chromophils
chromophobes
gamma cells
_____________ techniques can be used to classify the cells by their hormone contents
immunoperoxidase
Located between the pars distalis and pars nervosa
Composed of a thin layer of cells and vesicles containing acidophilic colloidal substance
Parenchymal cells are known as MELANOTROPHES
pars intermedia
It consists of supporting cells resembling neuroglial cells, the pituicytes and terminal portions of the axons of the supraoptic and paraventricular nuclei of the hypothalamus.
pars nervosa/neurophysis
accumulations of neurosecretory materials in nerve terminals.
HERRING BODIES
composed of unmyelinated, tangled nerve fibers that discharge ADH & oxytocin, produced in the hypothalamus and stored in Herring bodies, into blood stream.
Normal Posterior Pituitary Gland
HYPERPITUITARISM
3
- Gigantism
- Acromegaly
- Hyperprolactinaemia
cells that secrete CALCITONIN
PARAFOLLICULAR CELLS - secrete CALCITONIN
important distinguishing histological feature of thyroid gland
Cuboidal epithelium with an orderly arrangement of the nuclei around the follicles -
the structural unit of the gland compose the lobules.
THYROID FOLLICLES
, which is filled with colloid representing the stored product of the follicular lining epithelium.
FOLLICULAR CAVITY
FUNCTIONS OF THE THYROID GLAND
Synthesize, store and release hormones THYROXIN (T4) & TRIIODOTHYRONINE (T3) for regulation of metabolic rate
Elaboration of calcitonin by parafollicular (C) cells – lowers plasma calcium concentration
The parenchyma of parathyroid gland is composed of
masses and cords of epithelial cells
FUNCTIONS OF THE PARATHYROID
1) Essential for life; they elaborate parathormone which is important in the regulation of calcium metabolism.
2) Decreases the concentration of phosphatase.
3) With a direct effect on the ion transport in the kidney.
* Parathyroid responds directly to blood calcium level and are not under the control of other endocrine organs
A pair of triangular flattened yellowish organ embedded in the retroperitoneal adipose tissue. It is encapsulated and gives trabeculae into the cortex.
suprarenal/adrenal gland
suprarenal gland outer __________
bright yellow cortex
suprarenal gland inner _________
inner reddish brown zone
The adrenal glands are functionally and structurally 2 distinct parts:
1) Cortex / Inter-renal tissue
– mesodermal
2) Medulla / Chromaffin tissue
- ectodermal
adrenal cortex 3 zones
Divided into 3 zones:
Zona glomerulosa – outer zone
2) Zona fasciculate – middle zone
3) Zona reticularis – inner zone
Closely packed clusters and arcades of columnar cells arranged in hooked / horse shoe shaped slightly coiled columns
Zona glomerulosa
Spheroidal nucleus; deeply stained with one or two nucleoli; acidophilic cytoplasm
Zona glomerulosa
Secretes mineralocorticoid hormones (aldosterone & deoxycorticosterone) - for fluid & electrolyte balance
Zona glomerulosa
Composed of cell cords parallel to one another; usually one or two cells in width; separated by a longitudinally arranged sinusoidal capillaries
W/ vesicular nucleus and cytoplasm w/ abundant amount of lipid droplets (cholesterol, fatty acids & neutral fats).
Zona Fasciculata
Zone that Secretes glucocorticoids.
Zona Fasciculata
Cells of zona fasciculata appear vacuolated and spongy, hence, they are called .
SPONGIOCYTES
Thinnest and least distinct
Cells are arranged in cords to form an anastomosing network.
The secretory cells produce the SEX HORMONES.
Zona Reticularis
Closely packed clumps of secretory cells w/ numerous wide diameter capillaries.
W/ large vesicular nuclei and a strongly basophilic cytoplasm with fine chromaffin granules.
Granules become brown with potassium dichromate (Zenker’s fixative); secretory cells known also as chromaffin cells
adrenal medulla
- brown coloration of the granules when exposed to chromium salts due to the oxidation of epinephrine and norepinephrine within the granules of the cells.
CHROMAFFIN / PHEOCHROME REACTION
Cells containing ————– exhibit a stronger positive chromaffin reaction than adrenalin containing cells (epinephrocytes)
noradrenalin (norepinephrocytes)
On E/M, the most characteristic feature of adrenal medulla is the ———–
presence of numerous membrane bound dense granules.
Widely scattered groups of cells that are similar to the medullary cells of the adrenal gland (chromaffin cells).
Cells of the paraganglia and cells of the adrenal medulla (“CHROMAFFIN SYSTEM”).
paraganglia
(lumbar aortic paraganglia)
Paired para-aortic bodies of Zukerkandle
Component cells of paraganglia are —————– and give positive pheochrome reaction.
“CHROMAFFIN CELLS”
The endocrine portion of the pancreas are known as the
ISLET OF LANGERHANS
3 types of secretory cells with Mallory-Azan stain:
alpha cells
beta cells
delta cells
3 types of secretory cells with Mallory-Azan stain
large granules; colored brilliant red; less numerous, found in the periphery of the islet.
secrete glucagon
1) ALPHA (A cells)
3 types of secretory cells with Mallory-Azan stain
smaller cells; located in the interior of the islet; stains brown with Mallory Azan.
60-90% of all islet cells.
synthesize insulin
2) BETA cells
3 types of secretory cells with Mallory-Azan stain
w/ blue staining granules by Mallory-Azan stain.
secrete somatostatin
3) DELTA cells
