Microscopy of the hypothalamus, the hypothalamo-hypophyseal system
Viktória Vereczki M.D., PhD.
Department of Anatomy,
Histology and Embryology
Semmelweis University
11.25. 8:00 a.m. 2011.
The structure of hypothalamus
Preoptic area
lateral preoptic nucleus
medial preoptic nucleus: tr. hypothalamo-hypophysealis LHRH
Lateral zone:
Cardiovascular functions, regulation of food and water intake
lateralis hypothalamic nucleus
tuberal nuclei
medial forebrain bundle
Preoptic area
Medial zone
1. regio anterior ( supraoptic region) supraoptic n.: supraopticohypophyseal tract (VAS, OXI) paraventricular n.: paraventriculohypophysealis tract (VAS, OXI) anterior n. suprachiasmatic n.: retinohypothalamic tract (VIP)
2. medial region ( tuberal region) ventromedial n. :satiety center dorsomedial n.: behavioral center arcuate n.: tr. hypothalamo-hypophysealis (relasing hormons)
3. posterior region (mamillary region) mamillary bodies dorsal hypothalamic nucleus
Medial Zone 1.
Medial zone
1. regio anterior ( supraoptic region) supraoptic n.: supraopticohypophyseal tract (VAS, OXI) paraventricular n.:paraventriculohypophysealis tract(VAS, OXI) anterior n. suprachiasmatic n.: retinohypothalamic tract (VIP)
2. medial region ( tuberal region) ventromedial n. :satiety center dorsomedial n.: behavioral center arcuate n.: hypothalamo-hypophyseal tract (releasing hormons)
3. posterior region (mamillary region) mamillary bodies dorsal hypothalamic nucleus
Medial Zone 2.
regio anterior regio posteriorregio medialis
Afferent connections:
1. Fornix hippocampus-subicumum mamillary bodies 2. Medial forebrain bundle septum pellucidum zona lateralis hypothalami
tegmentum mesencephali3. Stria terminalis corpus amygdaloideum zona preoptica, medialis
hypothalamus4. Others: reticular formation (Ser, NA) nucleus of solitary tract parabrachial nucleus dorsomedial nucleus of thalamus retina prefrontal cortex
Afferent connetions of hypothalamus
Efferent connections:
A .
Reciprocal paths to the limbic
systemB. Descending
polysynaptic paths to lower autonomic and motor center
C.
Nervous and vascular links with the hypophysis:
Hypothalamo-hypophyseal
system
Efferent connections:
1. Fornix hippocampus-subicumum mamillary bodies
2. Medial forebrain bundle septum pellucidum zona lateralis hypothalami mesencephalic tementum
3. Stria terminalis corpus amygdaloideum zona preoptica, medialis hypothalamus
4. Mamillothalamic (Vicq d’Azyr) tract , part of the PAPEZ –ring mamillary bodies anterior thalamic nucleus
5. Hypothalamospinal tract paraventricular n. n. dorsalis nervi vagi és dorsomedial n. n. tr. solitarius
6. Dorsal longitudinal fascicle (Schütz-bundle) medial zone of hypothalamus substantia grisea centralis of mesencephalon
7. Mamillotegmental tract: mamillary bodies reticular formation of mesencephalic tementum
Efferent connetions of hypothalamus
Regulation of endocrine organsKözp. idegr.
Releasing hormon (pl. CRF)
Adenohypophysis sejt (pl. corticotrop)
Glandotrop hormon (pl. ACTH)
•Neurosecretion: secreration of
neruon gets to the bloodstream
NEUROENDOCRINOLOGY
„The hypothalamus is the „head
ganglion” of the autonomic nervous
system (Sherrington1947)
•Portal circulation of hypophysys:
hypothalamic factors reach directly
the adenohypophysist
•Glandotrop hormons through
systematic circulation reach endocrin
glands
•Negative feedback: hormons of
targeted organ inhibit the
adenohypophysis
Hypothalamo-hypophyseal system
LPV: Long portal vessels
Vessels of the hypophysis
Arteries (from ICA)SHA: Superior hypophyseal arteryIHA: Inferior hypophyseal artery
SPV: short portal vessels
Portal vesselsCarrying hormone releasing factors
Lateral hypophyseal vein
Drains to cavernous sinus
1.Parvocellular
tuberoinfundibular tract
Tuberal nuclei:
Arcuate nucleus (DA)
Periventricular zone
Paraventricular nucleus parvocellular part
Supraopticus parvocellular part
hypothalamic hormone Effect
CRH POMC: ACTH+
β-LPH+
TRH TSH+
LHRH (GnRH) FSH+, LH+
GHRH GH+
DA PL-
Somatostatin GH-, TH-
Paraventricular nucleus
Tuberal nuclei
2. Magnocellular hypothalmo-neurohypophyseal system
Paraventricular nucleus magnocellular part
Supraoptic nucleus magnocellular part
hormones effect
Antidiuretic or resorption of water
vasopressin
Oxytocin 1. ejection of milk
2. uterine contraction
Herring –bodies store them
(neurophysisn 1 and 2) in the
neurohypophysis
N.paraventricularis N.supraopticus
Eminentia mediana
EZ
TRH
IZ
EZAVP
AVP= Arginin-Vasopressin
TRH= thyreotropin releasing hormon
(Dr. Kántor O.)
Neurohypophysis:
Terminations of Supraotico-paraventriculohypo-physeal tract
Herring –bodies store OXI and Vas(neurophysisn 1 and 2) in the neurohypophysis
Effects of oxytocin, vasopressin
Oxytocin:
♀: uterus: contraction during delivery
breast: contraction of myoepithel cells → ejection of milk
♂: role in ejaculation?
Vasopressin (antidiuretic hormon, ADH):
kidney: distal convoluted tubules and collecting ducts Aquaporin-2 (water channel) → reauptake of water, concentration of urine.
Destruction of the magnocellular hypothalamo-hypophysial tract:
diabetes insipidus
vessels: vasoconstrictor → elevates blood pressure ↑
♂: role in sexual attachment
Functions of hypothalamus
1. thermoregulation2. food intake3. water metabolism4. behavior:emotions, sexual behavior, 5.control of circadian rhytms (SCH, tr retinohypothalamicus
Functions of hypothalamus
1. thermoregulation2. food intake3. water metabolism4. behavior:emotions, sexual behavior, 5.control of circadian rhytms (SCH, tr retinohypothalamicus
Functions of hypothalamus
1. thermoregulation2. food intake3. water metabolism4. behavior:emotions, sexual behavior, 5.control of circadian rhytms (SCH, tr retinohypothalamicus
Functions of hypothalamus
1. thermoregulation2. food intake3. water metabolism4. behavior:emotions, sexual behavior, anger reactions 5.control of circadian rhytms (SCH, tr retinohypothalamicus
Functions of hypothalamus
1. thermoregulation2. food intake3. water metabolism4. behaviour:
emotions, sexual behavior, anger,etc.5. control of circadian rhytms (SCH, tr retinohypothalamicus
ICC of Orexin in narcoleptic patient compared to control
Medial zoneSuprachiasmaticus nucleus (VIP) : retinohypothalamic tract of rat(Scale: 100 µm. OX= optic chiasm;SCH=suprachiasmatic nucleus)
5. control of circadian rhytms: retinohypothalamic tract
Clinical disorders associated with hypothalamic lesions
-Obesity and wasting
-bulimia or anorexia
-Sexual disorders :
In childood: pubertas precox,
sexual retardation
After puberty: impotence or amenoohea
4,5 years old boy suffering in pubertas precox
-Hyperthermia and hypothermia
-Diabetes insipidus
Literature
Williams PL, Marwick R, Dyson M, Bannister LH. Gray’s Anatomy 37th ed. (Churchill Livingstone, 1989)
Antony L. Mescher: Junqueira’s Basic Histology 12th ed.( Mc Gaw Hil, 2010)
Netter’s concise Neuroanatomy
Richard S. Snell: Clinical Neuroanatomy for medical students 3rd ed.(Little, Brown and Co. 1992)