endocrine glandsnikolai.lazarov.pro/files/pharmacy_eng/endocrine_glands.pdfendocrinology prof. dr....

Endocrine 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 Lazarov

Endocrine system� Endocrine glands:

� work parallel (in concert) with the immune and nervous systems

� neurohumoral regulation of body functions

� Anatomical peculiarities:� 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:� amino acid-derived hormones� peptide hormones – secretory granules

o small proteinso glycoproteins

� lipid derivatives� steroid hormones – cholesterol� eicosanoids – prostaglandins

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Endocrine glands

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� Endocrine cells:� aggregated as distinct endocrine glands:

� pituitary gland� pineal gland� thyroid gland� parathyroid glands� adrenal glands

� a 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 cells – paracrine signaling

� intestinal enteroendocrine cells

� Typical arrangement of endocrine tissue:� in radially arranged cords or

in narrow anastomosing cords� adenohypophysis� parathyroid glands� adrenal glands

� epithelial vesicles – follicles� thyroid gland

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Pituitary gland, hypophysis

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� Pituitary gland, hypophysis cerebri(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

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Macroscopic anatomy

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� Anatomical parts:� anterior pituitary,

adenohypophysis (anterior lobe):� pars distalis – 75% of the mass� pars intermedia� pars tuberalis

� posterior pituitary, neurohypophysis (posterior lobe):� lobus nervosus – 25% of the mass� infundibulum

o pedunculus infundibulariso eminentia mediana

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Microscopic anatomy

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� Adenohypophysis – cell types:� chromophobes, endocrinocyti chromophobi:

� 50-60% of the cell population� small (12-15) agranular cells� stem cells

� chromophils, endocrinocyti chromophili:� acidophilic cells, endocrinocyti acidophili – 30-40%

� somatotropic cells – STH� mammotropic cells – prolactin (luteotropic hormone)

� basophilic cells, endocrinocyti basophili – 4-10%� gonadotropic cells – FSH and LH� thyrotropic cells – TTH and TSH� corticotropic cells – ACTH and MSH (melanotropin)

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Microscopic anatomy

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� Neurohypophysis:� pituicytes, pituicyti:

� 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 – 2%:� weakly basophilic cells

– MSH (intermedin)� chromophobes

– Rathke’s cleft cysts

� Pars tuberalis – 2%:� a funnel-shaped region� arranged in cell cords –

gonadotropins (FSH and LH)� small follicles

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Effects of hypophyseal hormones

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NB: pituitary gland is the conductor of the endocrine orchestra!

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Prof. Dr. Nikolai Lazarov 9

� Hypothalamic nuclei:� nucleus supraopticus et paraventricularis

� tractus supraopticohypophysialis� tractus paraventriculohypophysialis

� axovasal synapses – neurohypophysis, Herring bodies

� Hypothalamic nuclei:� nucleus ventromedialis� nucleus dorsomedialis� nucleus infundibularis

� neurosecretory cells –releasing- and inhibitory-hormones

� rete capillare primarium ofeminentia mediana

� hypophyseal portal system,vv. portae hypophysis

Hypothalamo-hypophyseal portal system

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Pineal gland, epiphysis cerebri

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� Pineal gland, epiphysis cerebri (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

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Microscopic structure

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� Pineal parenchyma – cell types:� pinealocytes, endocrinocyti pineales

� arranged in cords and follicles

� production of melatonin and pineal peptides – vasotocin

� Pineal stroma:� neuroglial cells, 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

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Thyroid gland, glandula thyroidea

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� Thyroid gland, glandula 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

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Macroscopic anatomy

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� Anatomical parts:� two large lobes – conical in shape:

�right and left lobes

� isthmus gl. thyroideae

� length – 1-1.5 cm

�at ІІ-ІV tracheal cartilage

�pyramidal lobe,lobus pyramidalis

�variable in length

�occasionally absent

�remnant from ductus thyroglossus

�gll. thyroideae accessoriae

� thin fibrous capsule

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Microscopic anatomy

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� Thyroid parenchyma, parenchyma:� follicles, 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:o follicular cells,

thyrocytes• produce thyroid hormones,

triiodothyronine (T3) andthyroxine (T4)

• stimulation from TTH• thyroid colloid, thyroglobulin

o parafollicular cells, clear or light, C-cells

• secretion of calcitonin• part of the

follicular epithelium• isolated clusters

between thyroid follicles

o basal lamina

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Parathyroid glands, glandulae parathyroideae

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� Parathyroid glands, glandulae parathyroideae:� gll. parathyroideae superiores

� gll. parathyroideae inferiores� 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

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Microscopic anatomy� Parenchyma – lobulated structure:

� anastomosing cords of parenchymal cells,

parathyrocytes:

� chief (principal) cells, endocrinocyti principales

o small polygonal cells with granules

o contain parathyroid hormone

� oxyphil (eosinophil) cells,

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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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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Macroscopic anatomy� Two margins and three surfaces:

� margo superior et medialis� facies renalis – basis� facies anterior – hilum� facies posterior

� Anatomical parts:� adrenal cortex – a yellow

peripheral layer – 9/10

� adrenal medulla – a reddish-browncentral layer – 1/10

� capsule – two layers� subcapsular layer of

epithelial cells �accessory glands, gll. suprarenales accessoriae:� spermatic cord� epididymis� lig. latum uteri

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� Adrenal cortex – endocrinocytus 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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� Adrenal medulla – cellulae chromaffinae(medullary cells):� endocrinocyti lucidi � epinephrine

(adrenaline – 80%)� endocrinocyti densi � norepinephrine -

(noradrenaline – 20%)

�pheochromocytoma


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� Embryonic origin – neuroectoderm(neural crest)

� chromaffin cells, chromaffinocyti (type І)� epitheloid satellite cells (type ІІ)

� aortic bodies, paragangliа aortica(of Zuckerkandl) – 1 cm

� carotid body, glomus caroticum� jugular body, glomus jugulare – 0.5 mm

� coccygeal body, glomus coccygeum(Luschka’s gland) – 2-3 mm

Paraganglia

Emil Zuckerkandl (1849-1910)

Hubert Luschka (1820-1875)

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Endocrine testis� Interstitial cells (of Leydig),

endocrinocyti interstitiales –12% of the testicular volume

� Embryonic origin:� mesenchymal?� neuroectodermal?

� fenestrated capillaries� steroid-secreting cells – testosterone� hormonal control – luteinizing hormone

(LH or ICSH) from the hypophysis

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Endocrine ovary� endocrinocyti thecales, theca cells

– theca interna

� epitheliocyti folliculares, follicular or granulosa 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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Endocrine pancreas, pars endocrina pancreatis

� Islets of Langerhans, insulae pancreaticae Langerhansi

� number: > 1 million (1-2%)

� total weight: ~ 1 g� location: more abundant

in the tail, cauda pancreatis� size: diameter 100-300 µm � fine capsule of reticular fibers� a network of blood capillaries,

rete capillare

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Islets of Langerhans� three principal cell types, inculocyti:

� А (α)-cells – 15-20% � glucagon� B (β)-cells – 60-80% � insulin� D (δ)-cells (A1-cells) – 5-10% �

somatostatin

� other cell types – 5%:� PP (F)-cells – 2-5% �

pancreatic polypeptide� D1-cells – 0.5-1% �

vasoactive intestinal polypeptide� EC-cells – isolated �

secretin, motilin, substance P, serotonin, dopamine

� G-cells � gastrin� Y-cells � ghrelin

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Gastroenteropancreatic (GEP)endocrine system

� GEP = all the enteroendocrine (chromaffin) cellsof the digestive system

� APUD = Amine Precursor Uptake and Decarboxylation

� DNES = diffuse neuroendocrine system orparaneuron concept

AGE Pearse(1916-2003) 27

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Thank you ...

So, at long last, here are the glands!

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endocrine glandsnikolai.lazarov.pro/files/pharmacy_eng/endocrine_glands.pdfendocrinology prof. dr....

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