endocrine glands -...
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Endocrine glandsEndocrine glands
1. Endocrine glands overview
2. Pituitary gland, hypophysis cerebri
3. Pineal gland, epiphysis cerebri
4. Thyroid gland. Parathyroid glands
5. Suprarenal (adrenal) glands. Paraganglia
6. Endocrine pancreas – islets of Langerhans
7. Gonads
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Endocrine systemEndocrine system�� Endocrine glandsEndocrine glands::
� work parallel (in concert) with the immune and nervous systems
� neurohumoral regulation of body functions
� Anatomical peculiaritiespeculiarities::� do not have excretory ducts (ductless),
glandulae sine ductibus (PNA)
� secrete hormones directly into the blood� highly vascularized
� surrounded with a dense network of fenestrated capillaries
� produce small amounts of hormonesacting on distant target tissues
�� Chemical nature of hormones:Chemical nature of hormones:� amino acid-derived hormones� peptide hormones – secretory granules
o small proteinso glycoproteins
� lipid derivatives� steroid hormones – cholesterol� eicosanoids – prostaglandins
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Endocrine glandsEndocrine glands
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�� Endocrine cellsEndocrine cells::� aggregated asas distinctdistinct endocrineendocrine glandsglands:
� pituitary gland� pineal gland� thyroid gland� parathyroid glands� adrenal glands
�� a distinct part of certain organsa distinct part of certain organs:� islets of Langerhans in the pancreas� collection of cells in:
o hypothalamuso testis (Leydig cells)o ovary – follicular and theca cells
�� single endocrine cellssingle endocrine cells – paracrine signaling
� intestinal enteroendocrine cells
� Typical arrangement of endocrine tissue:� in radially arranged cords or
in narrow anastomosing cordscords� adenohypophysis� parathyroid glands� adrenal glands
� epithelial vesicles – folliclesfollicles� thyroid gland
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Endocrine glandsEndocrine glands
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�� Endocrine cellsEndocrine cells::� aggregated asas distinctdistinct endocrineendocrine glandsglands:
� pituitary gland� pineal gland� thyroid gland� parathyroid glands� adrenal glands
�� a distinct part of certain organsa distinct part of certain organs:� islets of Langerhans in the pancreas� collection of cells in:
o hypothalamuso testis (Leydig cells)o ovary – follicular and theca cells
�� single endocrine cellssingle endocrine cells – paracrine signaling
� intestinal enteroendocrine cells
� Typical arrangement of endocrine tissue:� in radially arranged cords or
in narrow anastomosing cordscords� adenohypophysis� parathyroid glands� adrenal glands
� epithelial vesicles – folliclesfollicles� thyroid gland
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Pituitary glandPituitary gland, , hypophysishypophysis
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�� Pituitary glandPituitary gland, , hypophysis cerebri hypophysis cerebri (Lat. glandula pituitaria)(Lat. glandula pituitaria)::
� small, unpaired body
� housed in the sella turcica
� overlapped by diaphragma sellae
� connected to the hypothalamus by a neural stalk, infundibulum
� External morphology:� ovoid shape
� weight ~0.5 g (>1 g multipara)
� size:
� length 8-10 mm
�width 12-15 mm
� height 5-6 mm
� color – reddish-grey
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Macroscopic anatomyMacroscopic anatomy
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� Anatomical partsparts::� anterior pituitary,
adenohypophysisadenohypophysis (anterior lobe):(anterior lobe):� pars distalis – 75% of the mass� pars intermedia� pars tuberalis
� posterior pituitary, neurohypophysisneurohypophysis (posterior lobe):(posterior lobe):� lobus nervosus – 25% of the mass� infundibulum
o pedunculus infundibulariso eminentia mediana
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Microscopic anatomyMicroscopic anatomy
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�� AdenohypophysisAdenohypophysis –– cellcell typestypes::� chromophobes, endocrinocyti chromophobiendocrinocyti chromophobi::
� 50-60% of the cell population� small (12-15) agranular cells� stem cells
� chromophils, endocrinocyti chromophili:endocrinocyti chromophili:� acidophilic cells, endocrinocytiendocrinocyti acidophiliacidophili – 30-40%
� somatotropic cells – STH� mammotropic cells – prolactin (luteotropic hormone)
� basophilic cells, endocrinocytiendocrinocyti basophilibasophili – 4-10%� gonadotropic cells – FSH and LH� thyrotropic cells – TTH and TSH� corticotropic cells – ACTH and MSH (melanotropin)
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Microscopic anatomyMicroscopic anatomy
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�� NeurohypophysisNeurohypophysis::� pituicytes, pituicytipituicyti::
� glial cells – 25% of its volume� highly branched processes
� neurosecretory axons � Herring bodies� axovasal synapses, synapses axovasculares� neurosecretory material:
o neurohypophyseal hormones• oxytocin• Arg-vasopressin (antidiuretic hormone, ADH)
o neurophysin – a binding glycoproteino АТP
� postganglionic sympathetic terminals –catecholamines
� axonal endings in synaptic contactwith neurosecretory terminals
�� Pars intermedia Pars intermedia – 2%:� weakly basophilic cells
– MSH (intermedin)� chromophobes
– Rathke’s cleft cysts
�� Pars tuberalis Pars tuberalis – 2%:� a funnel-shaped region � arranged in cell cords –
gonadotropins (FSH and LH)� small follicles
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Effects of hypophyseal hormonesEffects of hypophyseal hormones
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NB:NB: pituitary gland is the conductor of the endocrine orchestrapituitary gland is the conductor of the endocrine orchestra!!
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 1010
�� Hypothalamic nucleiHypothalamic nuclei::� nucleus supraopticus et paraventricularis
� tractus supraopticohypophysialis� tractus paraventriculohypophysialis
� axovasal synapses – neurohypophysis, Herring bodies
�� Hypothalamic nucleiHypothalamic nuclei::� nucleus ventromedialis� nucleus dorsomedialis� nucleus infundibularis
� neurosecretory cells –releasing- and inhibitory-hormones
� rete capillare primarium ofeminentia mediana
� hypophyseal portal system,vv. portae hypophysis
HHypothalamoypothalamo--hypophyseal hypophyseal portal systemportal system
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Pineal glandPineal gland, , epiphysis cerebriepiphysis cerebri
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�� Pineal glandPineal gland, , epiphysis cerebri epiphysis cerebri (Lat. glandula s. corpus pineale)(Lat. glandula s. corpus pineale)::� small, unpaired body
� part of the epithalamus
� occupies the depression between colliculi superiores
� connected with habenulae tocommissura habenularum
� recessus pinealis – third ventricle
� grows in size until 1-2 years of age; undergoes involution after age 7
� External morphology:� pine cone-shaped (piriform) body
� weight ~120 mg
� size:� length 5-8 mm
� width 3-5 mm
� height 5-6 mm
� color – reddish-grey organ
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Microscopic structureMicroscopic structure
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�� Pineal parenchymaPineal parenchyma –– cell typescell types::� pinealocytes, endocrinocytiendocrinocyti pinealespineales
� arranged in cords and follicles
� production of melatonin and pineal peptides – vasotocin
�� Pineal stromaPineal stroma:� neuroglial cells, gliocyti centrales gliocyti centrales – 5-10%
� astrocytes – supportive function
�microglial cells – phagocytic function
� calcified concretions or “brain sand”,acervuli cerebri (corpora aranacea)� up to 1 mm in diameter
� accrue with age � degenerative changes
� covered by pial connective tissue capsule
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Thyroid glandThyroid gland, , glandula thyroideaglandula thyroidea
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�� Thyroid glandThyroid gland, , glandula thyroideaglandula thyroidea::� the largest endocrine glands� anteriorly in the lower part of the neck
� External morphology:� a "butterfly" shape, thyroid (Gr. “shield”)� weight 20-40 g� size:
� transverse 3 cm� anterior-posterior 2 cm� height 5 cm
� color – brownish-red
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Macroscopic anatomyMacroscopic anatomy
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� Anatomical partsparts::� two large lobes – conical in shape:
�� right and left lobesright and left lobes
�� isthmus gl. thyroideaeisthmus gl. thyroideae
� length – 1-1.5 cm
�at ІІ-ІV tracheal cartilage
�pyramidal lobe,lobuslobus pyramidalispyramidalis
�variable in length
�occasionally absent
�remnant from ductus thyroglossus
�gll. thyroideae accessoriae
� thin fibrous capsule
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Microscopic anatomyMicroscopic anatomy
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�� Thyroid parenchymaThyroid parenchyma, , parenchymaparenchyma::� follicles, folliculi gl. thyroideae folliculi gl. thyroideae
� total number – 20-30 million� spherical or ovoid structures, d=35-500 µm� contain a gelatinous substance, colloid
� secretory product is stored in great quantity
� surrounded by an extensive lymphatic and fenestrated blood capillary network
� simple cuboidal secretory epithelium:oo follicular cellsfollicular cells, ,
thyrocytesthyrocytes• produce thyroid hormones,
triiodothyronine (T3) and triiodothyronine (T3) and thyroxine (T4)thyroxine (T4)
• stimulation from TTH• thyroid colloid, thyroglobulin
oo parafollicular cellsparafollicular cells, , clear or light, Cclear or light, C--cellscells
• secretion of calcitonincalcitonin• part of the
follicular epithelium • isolated clusters
between thyroid follicles
o basal lamina
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Synthesis and accumulation Synthesis and accumulation of of thyroid thyroid hormoneshormones
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Parathyroid glandsParathyroid glands, , glandulae parathyroideaeglandulae parathyroideae
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�� Parathyroid glandsParathyroid glands, , glandulae parathyroideae:glandulae parathyroideae:
�� gll. parathyroideaegll. parathyroideae superioressuperiores
�� gll. parathyroideaegll. parathyroideae inferioresinferiores� usually four small glands
� variable number and location
� located behind the thyroid gland, at each end of its upper and lower poles
� sometimes embedded in the thyroid gland
� contained within a connective tissue capsule
� External morphology:� ovoid or bean-like shape
� total weight 30-50 mg
� size:� length 6 mm� width 3-4 mm� thickness 2-3 mm
� 'mustard yellow' color
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Microscopic anatomyMicroscopic anatomy�� ParenchymaParenchyma – lobulated structure:
� anastomosing cords of parenchymal cells,
parathyrocytesparathyrocytes::
� chief (principal) cells, endocrinocytiendocrinocyti principalesprincipales
o small polygonal cells with granules
o contain parathyroid hormone
� oxyphil (eosinophil) cells,
endocrinocyti oxyphilicae (acidophilicae)endocrinocyti oxyphilicae (acidophilicae)
o appear just before puberty
o up to 3% of the cell population
o larger in size
o unknown function
� intermediate forms
between chief and oxyphil cells
� adipose cells – more than 50%
of the gland in older people
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Adrenal (suprarenal) gland, glandula suprarenalis (adrenalis)
� orange-colored paired organs
� location:� in the retroperitoneum
� on the superior poles of the kidney, embedded in adipose tissue
� shape:� right – triangular
� left – half-moon shape
� size:� length – 5-6 cm
� width – 3-4 cm
� thickness – 1 cm
� weight:� right – 4-5 g
� left – 5-7 g
� size and mass – age-relatedand functionally variable
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Macroscopic anatomyMacroscopic anatomy� Two margins and three surfaces:
� margo superior et medialis� facies renalis – basis� facies anterior – hilum� facies posterior
� Anatomical partsparts:� adrenal cortexcortex – a yellow
peripheral layer – 99/10/10
� adrenal medullamedulla – a reddish-browncentral layer – 1/101/10
� capsule – two layers� subcapsular layer of
epithelial cells �accessory glands, gll. suprarenales accessoriae:� spermatic cord� epididymis� lig. latum uteri
2020
ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Microscopic structureMicroscopic structure
�� Adrenal cortexAdrenal cortex –– endocrynocytus corticalisendocrynocytus corticalis– steroid hormones:� zona glomerulosa (15%) – mineralocorticoids� zona fasciculata (60%) – glucocorticoids (cortisol)
� pars externa et interna
� zona reticularis (35%) –androgens and (possibly) glucocorticoids?
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
�� Adrenal medullaAdrenal medulla –– cellulae chromaffinae cellulae chromaffinae (medullary cells):� endocrinocyti lucidi � epinephrine
(adrenaline – 80%)� endocrinocyti densi � norepinephrine -
(noradrenaline – 20%)
��
pheochromocytomapheochromocytoma
Microscopic structureMicroscopic structure
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
� Embryonic origin – neuroectodermneuroectoderm(neural crest)
� chromaffin cells, chromaffinocyti (type І)� epitheloid satellite cells (type ІІ)
� aortic bodies, paragangliparagangliаа aortica aortica (of Zuckerkandl) – 1 cm
� carotid body, glomus caroticumglomus caroticum� jugular body, glomusglomus jugularejugulare – 0.5 mm
� coccygeal body, glomus coccygeum glomus coccygeum (Luschka’s gland) – 2-3 mm
ParagangliaParaganglia
Emil Zuckerkandl Emil Zuckerkandl (1849(1849--1910)1910)
Hubert Luschka Hubert Luschka (1820(1820--1875)1875)
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Endocrine testisEndocrine testis�� Interstitial cellsInterstitial cells ((ofof LeydigLeydig), ),
endocrinocyti interstitialeendocrinocyti interstitialess –12% of the testicular volume
� Embryonic originorigin:� mesenchymal?� neuroectodermal?
� fenestrated capillaries� steroid-secreting cells – testosterone� hormonal control – luteinizing hormone
(LH or ICSH) from the hypophysis
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Endocrine ovaryEndocrine ovary�� endocrinocyti thecalesendocrinocyti thecales, , thecatheca cellscells
– theca interna
�� epitheliocyti follicularesepitheliocyti folliculares, , follicular or follicular or granulosa cellsgranulosa cells – stratum granulosum
� fenestrated capillaries� synthesize estrogens (estradiol)
and gestagens (progesterone)� hormonal control – follicle-stimulating
hormone (FSH) and luteinizing hormone (LH) from the hypophysis
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Endocrine pancreasEndocrine pancreas, , pars endocrina pancreatispars endocrina pancreatis
�� Islets of LangerhansIslets of Langerhans, , insulae pancreaticae Langerhansiinsulae pancreaticae Langerhansi
�� numbernumber: > 1 million (1-2%)� total weightweight: ~ 1 g
�� locationlocation:: more abundant in the tail, cauda pancreatis
�� sizesize: : diameter 100-300 µm
�� fine capsule of reticular fibersfine capsule of reticular fibers
�� a network of blood capillariesa network of blood capillaries, , rete capillare
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Islets ofIslets of LangerhansLangerhans�� three principal cell typesthree principal cell types, , inculocytiinculocyti:
�� АА ((αα))--cellscells – 15-20% � glucagonglucagon
�� BB ((ββ))--cellscells – 60-80% � insulininsulin
�� D D ((δδ))--cellscells (A1-cells) – 5-10% �somatostatinsomatostatin
� other cell types – 5%:�� PPPP ((FF))--cellscells – 2-5% �
pancreatic polypeptidepancreatic polypeptide
�� DD11--cellscells – 0.5-1% �vasoactive intestinal polypeptidevasoactive intestinal polypeptide
�� ECEC--cellscells – isolated �
secretinsecretin, , motilinmotilin, , substancesubstance P, P, serotoninserotonin, , dopaminedopamine
�� GG--cellscells � gastringastrin
�� YY--cellscells � ghrelinghrelin
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ENDOCRINOLOGY
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov
Gastroenteropancreatic Gastroenteropancreatic ((GEP)GEP)endocrine systemendocrine system
� GEP = all the enteroendocrine (chromaffin) cellsof the digestive system
� APUD = Amine Precursor Uptake and Decarboxylation
� DNES = diffuse neuroendocrine system or
paraneuronparaneuron conceptAGE PearseAGE Pearse(1916(1916--2003)2003) 2828