BGD Lecture - Endocrine Histology
Introduction
This lecture introduces Endocrine Histology, particularly of the HPA axis, that will also be covered in an associated practical class. A second Lecture next week will describe how these organs form during development.
Interested in hormone history? |
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Listen ABC Radio Ockham's Razor 2005-07-31 - Centenary of the word "hormone" Sydney medical scientist and writer Dr John Carmody commemorates the centenary of the entry of the word 'hormone' into the English language. Audio File | Listen Online |
- Lecture slides: 2013 Printable version | 2012 Lecture | PDF
Textbooks
Endocrinology - An Integrated Approach | |
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Endocrinology - An Integrated Approach Stephen Nussey and Saffron Whitehead.
St. George's Hospital Medical School, London, UK Oxford: BIOS Scientific Publishers; 2001. ISBN-10: 1-85996-252-1 http://www.ncbi.nlm.nih.gov/books/NBK22/ | |
Chapter 7. The pituitary gland
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- Histology on Notes Pages: Pineal | Hypothalamus | Pituitary | Thyroid | Parathyroid | Thymus | Pancreas | Adrenal
- Pituitary Histology: Pituitary overview | Anterior H&E | Anterior H&E | Anterior labeled | PAS/O Overview | Acidophils | Basophils | Posterior labeled | Posterior unlabeled | Histology Stains | BGD - Endocrine Histology | Pituitary Development
- Adrenal Histology: Cortex and Medulla | Unlabelled Overview | Cortical Zones | Zona Glomerulosa and Fasciculata | Zona Glomerulosa | Zona Fasciculata | Zona Reticularis and Medulla | Zona Reticularis | Medulla | Fetal Cortex | Developing Adult Cortex | BGD - Endocrine Histology | Histology Stains | Adrenal Development
Links: Histology | Histology Stains | Blue Histology images copyright Lutz Slomianka 1998-2009. The literary and artistic works on the original Blue Histology website may be reproduced, adapted, published and distributed for non-commercial purposes. See also the page Histology Stains.
Cite this page: Hill, M.A. (2024, June 16) Embryology BGD Lecture - Endocrine Histology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGD_Lecture_-_Endocrine_Histology
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
Hormones
Hormone Types
- Amino acid derivatives - noradrenaline (norepinepherine), adrenalin (epinepherine) , thyroid hormone
- Proteins, peptides - thyroid stimulating hormone, leutenising hormone, follicle stimulating hormone
- Steroids - androgens, glucocorticoids, mineralocorticoids
Hormone Actions
- Autocrine - acts on self (extracellular fluid)
- Paracrine - acts locally (extracellular fluid)
- Endocrine - acts by secretion into blood stream (endocrine organs are richly vascularized)
Hormone Receptors
- Cell surface receptors - modified amino acids, peptides, proteins
- Cytoplasmic/Nuclear Receptors - steroids
Hypothalamic Pituitary Adrenal (HPA) Axis
Endocrine feedback system
Other Endocrine Axes
Hypothalamus
- essential for the maintenance of homeostasis.
- regulation of eating, drinking, reproductive and parental behavior, and sleep-wake rhythms.
- controls the autonomic nervous system and hormone secretion.
- rostral-caudal axis - preoptic, anterior, tuberal and mammillary.
- medial-lateral axis - periventricular, medial and lateral zones.
Human hypothalamus nuclei locations.
- Links: Hypothalamus Development | Box 7.3 Anatomy of the functional connections between the hypothalamus and pituitary gland
Pituitary
- hypophysis - pars distalis, pars intermedia, pars nervosa
- pars intermedia - lies between the other 2 parts and consists mainly of colloid filled cysts.
- infundibulum - (infundibular stalk) connection between hypothalamus and the posterior pituitary.
- pars tuberalis - wraps the infundibulum in a highly vascularized sheath, part of the anterior pituitary.
- sits within a cavity in the skull base - the "sella turcica" (Turkish saddle), named historically by its similarity in shape.
- 2 embryonic origins, larger in females than males after pregnancies.
- (phil= likes, phob = hates)
Blood supply
- hypothalamus - blood supply from the circle of Willis.
- pituitary - blood from the inferior (neurohypophysis) and superior (adenohypophysis) hypophyseal arteries.
- inferior hypophyseal artery capillary plexus drains into the dural sinus.
- neural stalk some capillaries form about 20+ "short" portal veins that drain into the anterior pituitary gland.
- most of anterior lobe has no direct arterial supply, with large fenestrated sinusoidal capillaries.
- hypophyseal vein then drains into systemic venous blood.
Pituitary - Neurohypophysis
- posterior pituitary
- cells are pituicytes and also present are hypothalamic neurosecretory cell unmyelinated nerve fibres (from the supraoptic and paraventricular nuclei).
- pituicyte - oval or round nuclei are visible, branched cytoplasm, associated with fenestrated capillaries (resemble glial cells).
- Herring bodies are dilations of nerve fibres filled with small neurosecretory vesicles.
- nerve fibres terminate close to capillaries.
- hormones are releasing and release-inhibiting factors produced regulating adenohypophysis activity (as well as 2 other 9 aa hormones).
- Oxytocin - pregnancy stimulates uterine smooth muscle the contraction and lactation milk ejection reflex.
- Antidiuretic hormone - (ADH, vasopressin, arginine vasopressin, AVP) acts on kidneys to concentrate urine (water retention).
Neurohypophysis | Herring Bodies (EM) packed with neurosecretory granules. |
Pituitary - Adenohypophysis
- anterior pituitary - 3 parts pars distalis, pars tuberalis and pars intermedia.
- pars distalis of the adenohypophysis occupies about 75% of the hypophyseal tissue.
- stromal connective tissue - very little visible.
- parenchymal endocrine cells - arranged in irregular clumps or cords between a network of capillaries with large and irregular lumina.
- hormones are proteins or glycoproteins.
- H&E staining identifies 3 cell types:
- acidophil cells (acidophils)
- basophil cells (basophils)
- chromophobe cells
Acidophil cells
- about 65% of all cells.
- rounded and smaller than basophil cells (other stains identify subtypes).
- Somatotrophs - produce growth hormone (GH or somatotropin), stimulates liver cells to produce polypeptide growth factors which stimulate growth (stain with orange G)
- Mammotrophs - (lactotrophs) produce prolactin, maternal numbers increase in third trimester and postnatally in early lactation.
Basophil cells
Based on their hormone products basophils are divided into three subtypes (PAS stain all types reddish).
- Thyrotrophs - produce thyroid stimulating hormone (TSH or thyrotropin).
- Gonadotrophs - produce follicle stimulating hormone (FSH) and luteinizing hormone (LH)
- FSH stimulates in the male seminiferous tubule and female early follicular growth.
- LH stimulates male Leydig cell testosterone production and female oestrogen (estrogen) production, late follicular maturation, formation of corpus luteum.
- Corticotrophs - (or adrenocorticolipotrophs) produce adrenocorticotropic hormone (ACTH or corticotropin) and lipotropin (LPH).
- cell type in the pars intermedia where ACTH and LPH precursor undergoes hydrolysis into melanocyte stimulating hormone (MSH) and other peptides.
Chromophobe cells
- cells are unstained or weakly stained cells.
- either acidophils or basophils in a dormant or recently degranulated stage.
- may also include the secretory stem cells.
Adrenal
Adrenal Cortex
- divided into three zones (Adrenocorticotropic hormone (ACTH) required for zones 2 and 3)
- zona glomerulosa (about 15%)
- zona fasciculata (about 75%)
- zone reticularis is (about 10%)
Zona Glomerulosa
- secretes mineralocorticoids.
- Small cells arranged into small rounded groups or curved columns.
- not influenced by ACTH.
Zona Fasciculata
- secretes glucocorticoids.
- cell cords arranged radially arranged cell cords separated by fenestrated sinusoid capillaries.
- cell nucleus is light and centrally located.
- cell cytoplasm is also light and often "foamy" or "spongy" appearance (due to lipid droplets)
Zona Reticularis
- secretes adrenal androgens.
- cell chords separated by sinusoid spaces.
- small cells with large nucleus, and eosinophilic cytoplasm and less spongy. (lipofucsin accumulates with age, orange colour in H&E).
Zona Glomerulosa and Fasciculata |
Zona Reticularis and Medulla |
Adrenal Medulla
Histology Images
Pituitary
- Pituitary Histology: Pituitary overview | Anterior H&E | Anterior H&E | Anterior labeled | PAS/O Overview | Acidophils | Basophils | Posterior labeled | Posterior unlabeled | Histology Stains | BGD - Endocrine Histology | Pituitary Development
Adrenal
- Adrenal Histology: Cortex and Medulla | Unlabelled Overview | Cortical Zones | Zona Glomerulosa and Fasciculata | Zona Glomerulosa | Zona Fasciculata | Zona Reticularis and Medulla | Zona Reticularis | Medulla | Fetal Cortex | Developing Adult Cortex | BGD - Endocrine Histology | Histology Stains | Adrenal Development
Links: Histology | Histology Stains | Blue Histology images copyright Lutz Slomianka 1998-2009. The literary and artistic works on the original Blue Histology website may be reproduced, adapted, published and distributed for non-commercial purposes. See also the page Histology Stains.
Cite this page: Hill, M.A. (2024, June 16) Embryology BGD Lecture - Endocrine Histology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGD_Lecture_-_Endocrine_Histology
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
Additional Information
Not part of today's lecture.
Abnormalities
- Pituitary adenoma - often benign, different effects depending upon cellular function.
- Cushings syndrome - (Itsenko-Cushing disease) increased ACTH from pituitary adenoma.
- Adrenal tumor - adenoma, neuroblastoma.
History
- 1905 - Introduction of the word "hormone" into the English language. Audio File | Listen Online
- 1930 - First description of the portal system PMID 17104309 PDF
Terms
- ACTH - adrenocorticotropic hormone or corticotropin.
- adrenaline - (adrenalin, epinephrine) adrenal medulla secreted hormone (also a neurotransmitter), synthesised from tyrosine (amino acid). Many roles throughout the body on many tissues.
- adrenal androgen - zonula reticularis secreted weak steroids or steroid precursors (dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione).
- FSH - follicle stimulating hormone.
- glucocorticoid - adrenal zona fasciculata secretes glucocorticoids (mainly cortisol). Named by their role in glucose metabolism, these steroid hormones bind to the glucocorticoid receptor.
- HPA - Hypothalamic Pituitary Adrenal endocrine axis.
- mineralocorticoid - adrenal zona glomerulosa secreted steroids (mainly aldosterone). Named by their effect on mineral metabolism, acts on the kidney promoting reabsorption of sodium ions (Na+), with water following the salt.
- PAS - Periodic acid-Schiff histological stain.
- TSH - thyroid stimulating hormone or thyrotropin.
Glossary Links
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2024, June 16) Embryology BGD Lecture - Endocrine Histology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGD_Lecture_-_Endocrine_Histology
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G