Post on 14-Jan-2016
Depart. Of Histology & EmbryologyDepart. Of Histology & EmbryologyDepart. Of Histology & EmbryologyDepart. Of Histology & Embryology
Why can you grow
up?
General description• ComponentsComponents
Endocrine glands Endocrine glands Endocrine tissues Endocrine tissues Endocrine cellsEndocrine cells
• FunctionFunction
Endocrine systemEndocrine systemproduce HormonesHormones
target organstarget organs
Act on
target cellstarget cells
Chemical messengers secreted by endocrine glands that transfer information and instructions from one set of cells to other cells.
What is hormone?
Endocrine glands
Thyroid gland
Adrenal glands
Pituitary gland
General description• ComponentsComponents
Endocrine glands Endocrine glands Endocrine tissues Endocrine tissues Endocrine cellsEndocrine cells
• FunctionFunction
Endocrine systemEndocrine systemproduce HormonesHormones
target organstarget organs
Act on
target cellstarget cells
What is hormone?Chemical messengers secreted by endocrine glands that transfer information and instructions from one set of cells to other cells.
Hormones secretion
Special secreting formsSpecial secreting forms
AutocrineAutocrine
ParacrineParacrine
common features
⑴ ⑴ DuctDuctlessless
⑵ ⑵ Endocrine cells arrange into nests, cords, clusters or folliclesEndocrine cells arrange into nests, cords, clusters or follicles
⑶ ⑶ RichRich in capillaries in capillaries
Two types of endocrine cells
Nitrogenous-hormone secreting cell
Steroid-hormone secreting cell
Thyroid gland
• General structureGeneral structure
------ capsule : L.C.T capsule : L.C.T
forming septaforming septa
--- parenchyma: --- parenchyma:
lobuleslobules
follicles follicles
interstitium: CTinterstitium: CT
Constitution: Constitution: Follicle: Colloid is surrounded by a single layer epithelium.
1. Epithelium: Simple squamous (hypoactive), cuboidal or columnar (hyperactive), depending upon the functional status.
Thyroid gland follicles
2. Colloid: Homogeneous
secretion of epithelium.
Acidophilic and PAS (+).
Contains iodinated thyroglobulin.
Thyroid gland follicles Follicular epithelial cells Follicular epithelial cells EM:EM:
• microvillimicrovilli
• RER, Golgi apparatus RER, Golgi apparatus
secretory granulessecretory granules
• lysosome, mitochondrionlysosome, mitochondrion
endocytotic vesiclesendocytotic vesicles
Function:Function: synthesize and release thyroid hormonessynthesize and release thyroid hormones
thyroxine (T4)thyroxine (T4)
triiodothyronine (T3)triiodothyronine (T3)
According to the structures of follicular epithelial cells, According to the structures of follicular epithelial cells, can you illustrate their functions?can you illustrate their functions?
What is the secretory process?
i. i. SynthesisSynthesis of thyroglobulin of thyroglobulin
ii. ii. Iodination Iodination of thyroglobulinof thyroglobulin
iii. iii. ReleaseRelease of thyroid hormones of thyroid hormones
Formation of T3 & T4:
a. AA→ RER→ thyroglobulin →
(Gogi, glycosylated→ (G,
secreting granules) → colloid.
b. Iodide → (iodide pump) →
iodide oxidation in cytoplasm
→ colloid → bound to tyrosine
residues of thyroglobulin →
iodated thyroglobulin.
c. iodated thyroglobulin →
(TSH, microvilli) → endocytic
vesicles →LYS → T3 & T4.
Function of T3, T4:Function of T3, T4:
a. elevate the basal metabolic
rate.
b. influence the body growth
and nervous system
development during fetal life.
Modulation of T3, T4 secretion:Modulation of T3, T4 secretion:
hypothalamus-pituitary-thyroid axis
Pathological state
hypothyroidismhypothyroidism
exophthalmic goiter
In adults, thyroid hormone overproduction underproduction
myxoedema
hyperthyroidism
hyperthyroidism
A consequence of an increase in A consequence of an increase in
body’s metabolism:body’s metabolism:
Clinical features:Clinical features:
★ ★ feeling hotfeeling hot
★ ★ increased sweatingincreased sweating
★ ★ weight loss, with poximal weight loss, with poximal
muscle weaknessmuscle weakness
★ ★ rapaid heart raterapaid heart rate
★ ★ anxiety and restlessanxiety and restless hyperactivityhyperactivity
★ ★ diarrhoeadiarrhoea
Thyroid hormone deficiency slows Thyroid hormone deficiency slows
body processes:body processes:
Clinical features:Clinical features:
★ ★ dry, puffy skindry, puffy skin
★ ★ inability to keep warminability to keep warm ★ ★ weight gainweight gain
★ ★ a slow heart ratea slow heart rate
★ ★ loss of energy and appetiteloss of energy and appetite ★ ★ constipationconstipation
Pathological state
Hypothyroidism present at birth:Hypothyroidism present at birth: Mental retardation Mental retardation Short statureShort stature Coarse facial featuresCoarse facial features Protruding tongueProtruding tongue Umbilical herniaUmbilical hernia
Parafollicular cell------single between follicular cellssingle between follicular cells---in small groups in interstitial tissue---in small groups in interstitial tissueAlso calledAlso called calcitonin cell / C cell calcitonin cell / C cell
LM:LM:
• ovoid, polygonalovoid, polygonal
• largerlarger
• pale-stained: eosinophilicpale-stained: eosinophilic
• argyrophilic granulesargyrophilic granules
Function:Function:
synthesize and release synthesize and release calcitonin, calcitonin, make blood calcium make blood calcium
Parathyroid gland
• Structure Structure capsulecapsule parenchyma parenchyma
• FunctionFunction
synthesize parathyroid synthesize parathyroid
hormone (PTH)hormone (PTH)
make blood calcium make blood calcium
glandular cellsglandular cells chief cellschief cells
oxyphil cellsoxyphil cellsstromastroma
------capsule:capsule: CT CT
------cortex:cortex: yellow, yellow,
derived from derived from mesodermmesoderm
------medulla:medulla: reddish- reddish-
brown, derived from brown, derived from
neural ectodermneural ectoderm
Adrenal gland
Adrenal gland cortex
Zona glomerulosaZona glomerulosa
Zona fasciculataZona fasciculata
Zona reticularisZona reticularis
Zona glomerulosa
Zona fasciculata
Zona reticularis
Zona glomerulosa15% of cortex volume15% of cortex volume
---Structure: ---Structure:
LMLM
cellscells: small, low columnar: small, low columnar
or polygonal or polygonal
be arranged into nests or clustersbe arranged into nests or clusters
nucleinuclei: deep stained, round: deep stained, round
cytoplasmcytoplasm: light basophilic: light basophilic
---Function: ---Function:
secrete secrete mineralomineralocorticoid corticoid ( eg. aldo( eg. aldosteronesterone))
regulate electrolyte homeostasis and water balanceregulate electrolyte homeostasis and water balance
Zona fasciculataAbout 78% of cortex volumeAbout 78% of cortex volume
---Structure:---Structure:
LMLM
cells cells : large: large ,, clear margin clear margin
be arranged in straight cordsbe arranged in straight cords
cytoplasmcytoplasm: light staining: light staining
appear vacuolated(formy)-emptyappear vacuolated(formy)-empty
---Function:---Function:
secrete secrete glucoglucocorticosteroidcorticosteroid
(e.g cortisol(e.g cortisol 、、 corticosterone) and corticosterone) and androgenandrogen (less) (less)
regulate carbohydrate, protein and lipid metabolismregulate carbohydrate, protein and lipid metabolism
influence immune responseinfluence immune response
Zona reticularis
7% of cortex volume7% of cortex volume
---Structure---Structure::
LMLM
cellscells: polyhedral and small; : polyhedral and small;
be arranged in irregular be arranged in irregular
anastomosing cords anastomosing cords
cytoplasmcytoplasm: acidophilic: acidophilic
---Function:---Function:
secret secret androgenandrogen(testosterone) and(testosterone) and
small amount of small amount of oestrogenoestrogen
Adrenal medulla
---Structure:---Structure:
medullary cell ( chromaffin cell ) : medullary cell ( chromaffin cell ) :
LM:LM:
cellscells: polyhedral, be arranged in : polyhedral, be arranged in
nests or short cordsnests or short cords
cytoplasmcytoplasm: weakly basophilic,: weakly basophilic,
brownish granules- when fixed bybrownish granules- when fixed by
bichromate-containing fixative.bichromate-containing fixative.central veincentral vein
ganglial cellsganglial cells: multipolar neurons: multipolar neurons
large, 2large, 2~~3 in groups3 in groups
Adrenal medullaEMEM
electron-dense granules electron-dense granules
adrenaline celladrenaline cell: 80%: 80%
nornoradrenaline celladrenaline cell: 20%: 20%
Adr. cell
Noradr. cell
---Function: ---Function:
secrete adrenaline and secrete adrenaline and nornoradrenalineadrenaline
secrete some polypeptides(galanin, neuropeptide Y, enkephalin)secrete some polypeptides(galanin, neuropeptide Y, enkephalin)
i. heart ratei. heart rateii. dilate blood vesselii. dilate blood vessel
i. blood pressurei. blood pressure ii. the flow speed of bloodii. the flow speed of blood
Pathological state
Excessive adrenal secretion of Excessive adrenal secretion of glucoglucocorticoid hormonescorticoid hormones
Cushing’s syndromeCushing’s syndrome
Pituitary gland
pars nervosapars nervosa
infundibular stalkinfundibular stalk
median eminencemedian eminence
pars distalis pars distalis
pars intermedia pars intermedia
pars tuberalispars tuberalis
adenohypophysis
neurohypophysis
capsule: CTcapsule: CTanterior lobe
posterior lobe
Pituitary gland
Pituitary gland
Pars distalisPars intermedia
Pars nervosa
Infundibular
Pas distalis
Glandular cells are arranged in nests Glandular cells are arranged in nests
Rich in capillaries around the cellsRich in capillaries around the cells
Classification:
ChromoChromophobephobess
ChromoChromophilphilss Acidophils
Basophils
A --- AcidophilA --- Acidophilround or oval , eosinophilic stainninground or oval , eosinophilic stainningB --- BasophilB --- Basophilless, large cell, ovoid or polygonalless, large cell, ovoid or polygonalbasophilic granulesbasophilic granulesC --- ChromophobeC --- Chromophobemore, small, pale, no clear boundarymore, small, pale, no clear boundary
Tropic hormones of pas distalis
cell type secreting hormone cell type secreting hormone
acidophil acidophil
basophil basophil
somatotrope somatotropic hormone(STH) or growth hormone(GH)
mammotrope lactogenic hormone(LTH)or prolactin(PRL)
thyrotrope
gonadotrope
adrenocorticotropic hormone(ACTH)Lipotropin or lipotrophic hormone(LPH)
corticotrope
follicle stimulating hormone(FSH) luteinizing hormone(LH) interstitial cell-stimulating hormone(ICSH)---male
thyroid stimulating hormone(TSH)
Titan
Jack Sprat
Pathological state
Gigantism Dwarfism
Pathological stategrowth hormone in kidsgrowth hormone in kids
too muchtoo muchdeficientdeficient
Acromegaly
Pathological stateToo much growth hormone occurs in adultsToo much growth hormone occurs in adults
Protruding jawProtruding jawBroaden lower faceBroaden lower faceEnlarged handsEnlarged hands
Pas intermediaStructure:Structure:
chromophobe cellschromophobe cells
basophilsbasophils
be arranged into cords/follicles.be arranged into cords/follicles.
Function:Function:
Secrete melanocyte-stimulatingSecrete melanocyte-stimulating
hormone (MSH)hormone (MSH)
Pas tuberalis
Secrete gonadotropin.
Neurohypophysis
Pars nervosaPars nervosa
ComponentsComponents
• Pituicytes ( glial cells)Pituicytes ( glial cells)
• Capillaries (fenestrated)Capillaries (fenestrated)
• UnUnmyelinated nerve fibersmyelinated nerve fibers
Function:Function:
Store and release Store and release oxytocinoxytocin and and antidiuretic hormone (ADH)antidiuretic hormone (ADH)
Neurohypophysis
Herring bodies:Herring bodies:
Neurosecretory granules accumulate in the dilated portions of Neurosecretory granules accumulate in the dilated portions of
the axons near their terminals.the axons near their terminals.
LM:LM: acidophilic, irregular structure acidophilic, irregular structure
Blood supply (Hypophyseal portal system)
Superior hypophyseal artery
(Primary plexus)capillaries
Hypophyseal portal vein
( Secondary plexus ) capillaries
Hypophyseal vein
Relationship between hypothalamus and adenohypophysis
Arcuate nucleus of hypothalamus (neuroendocrine cell):
• secrete releasing hormones (RH)
-GRH, PRH, TRH, GnRH, CRH, MSRH
• secrete release inhibiting hormones (RIH)
-SOM, PIH, MSIH
• their axons end in infundibular stalk and release hormones into
primary capillaries network of hypophyseal portal circulation
• positive and negative feedback