Lecture - Endocrine Development: Difference between revisions
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==Introduction== | ==Introduction== | ||
[[File:Hypothalamus endocrine system.jpg|thumb|300px|Hypothalamus endocrine system]] | |||
[[File:Week10 adrenal.jpg|thumb|300px|Human adrenal gland ([[Second_Trimester|Week 10]])]] | [[File:Week10 adrenal.jpg|thumb|300px|Human adrenal gland ([[Second_Trimester|Week 10]])]] | ||
The endocrine system resides within specific endocrine organs and both organs and tissues with other specific functions. Epithelia (ectoderm and endoderm) form the majority of the “ductless” endocrine glands like gastrointestinal and skin associated “ducted” glands. Differentiation of several also organs involves a epithelial/mesenchye interaction, seen in repeated in many differentiation of many different tissues. The endocrine glands produce hormones, which are distributed by the vascular system to the many body tissues, subsequently these organs are richly vascularized. | The endocrine system resides within specific endocrine organs and both organs and tissues with other specific functions. Epithelia (ectoderm and endoderm) form the majority of the “ductless” endocrine glands like gastrointestinal and skin associated “ducted” glands. Differentiation of several also organs involves a epithelial/mesenchye interaction, seen in repeated in many differentiation of many different tissues. The endocrine glands produce hormones, which are distributed by the vascular system to the many body tissues, subsequently these organs are richly vascularized. | ||
Hormones “orchestrate” responses in other tissues, including other endocrine organs, and these overall effects can be similar or different in different tissues. These signaling pathways are often described as "axes" the two major types are the: '''HPA''' ('''H'''ypothalamus-'''P'''ituitary-'''A'''drenal) and '''HPG''' ('''H'''ypothalamus-'''P'''ituitary-'''G'''onad). These hormone effects (like music) can be rapid, slow, brief, diurnal, or long-term. Hormone effects can be mimicked, stimulated, and blocked by therapeutic drugs, nutritional and environmental chemicals. Importantly, fetal endocrine development is required for normal fetal growth and differentiation. | |||
| | <br> | ||
[[Media:ANAT2341Lecture 2018 - Endocrine Development.pdf|2018 Lecture - Print PDF]] | |||
==Lecture Objectives== | ==Lecture Objectives== | ||
* Understanding of hormone types | * Understanding of hormone types | ||
* Understanding of endocrine gland development | * Understanding of endocrine gland development | ||
* Understanding of endocrine developmental functions | * Understanding of endocrine developmental functions | ||
:: | {| class="wikitable mw-collapsible mw-collapsed" | ||
! Endocrine in the News | |||
|- | |||
| [[File:Human stem cell pancreas implants 01.jpg|300px|left|alt=Human stem cell pancreas implants|link=Stem Cells]] | |||
{{#pmid:26808346}} | |||
Implanted in the intraperitoneal space of mice treated to chemically induce type 1 diabetes. Implants induced glycemic correction without any immunosuppression until their removal at 174 d after implantation. Human C-peptide concentrations and in vivo glucose responsiveness demonstrated therapeutically relevant glycemic control and retrieved implants contained viable insulin-producing cells. | |||
:'''Links:''' [[Stem Cells]] | [[Endocrine - Pancreas Development]] | |||
|- | |- | ||
| [[File: | | [[File:Menstrual cycle.png|300px|left|alt=Menstrual cycle|link=Menstrual Cycle]] Oral Contraceptives A recent 2016 Danish study births from Danish registries between 1997 and 2011 identified that: | ||
{{#pmid:26738512}} | |||
:: | :'''Links:''' [[Menstrual Cycle]] | [[Abnormal_Development_-_Drugs|Abnormal Development]] | ||
|- | |- | ||
| [[File: | | [[File:Ernest Henry Starling (1866-1927).jpg|150px|left|alt=Ernest Henry Starling (1866-1927)|]]Ernest Henry Starling (1866-1927) | ||
Interested in hormone history? | |||
Listen ABC Radio Ockham's Razor 2005-07-31 Centenary of the word "hormone" (6.2 Mb mp3) [[Media:Audio - centenary of hormone.mp3| 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. | |||
<html5media>File:Audio - centenary of hormone.mp3</html5media> | |||
|} | |||
==Lecture Resources== | |||
{| class="wikitable mw-collapsible mw-collapsed" | |||
! Movies | |||
|- | |||
| valign="bottom"|{{Adrenal movie}} | |||
| valign="bottom"|{{Aschheim-Zondek1928 movie}} | |||
| valign="bottom"|{{Adrenal GA32 movie}} | |||
| valign="bottom"|{{Gastrointestinal stage 13 movie}} | |||
| valign="bottom"|{{Urogenital stage 22 movie}} | |||
|- | |||
|} | |||
{| class="wikitable mw-collapsible mw-collapsed" | |||
! colspan=2|References | |||
|- | |||
| {{Embryo logocitation}} | |||
| | |||
{{Endocrine Links}} | |||
* Lecture Archive: [https://embryology.med.unsw.edu.au/embryology/index.php?title=Lecture_-_Endocrine_Development&oldid=340760 2017] | [[Media:Lecture 2016 - Endocrine Development.pdf|2016 PDF]] | [https://embryology.med.unsw.edu.au/embryology/index.php?title=Lecture_-_Endocrine_Development&oldid=198711 2015] | [[Media:2015ANAT2341_Lecture_13_-_Endocrine Development.pdf|2015 PDF]][https://embryology.med.unsw.edu.au/embryology/index.php?title=Lecture_-_Endocrine_Development&oldid=144833 2014] | |||
|- | |||
| colspan=2|The endocrine "System" is not covered by a specific chapter in the embryology textbooks and you will need to look for related chapters on the development of individual components (some selected examples are listed below). Use the listed Endocrinology textbook for detained descriptions of function. | |||
|- | |||
| [[File:Endocrinology - An Integrated Approach.png|80px]] | |||
Nussey, S. and Whitehead, S. (2001). ''Endocrinology - An Integrated Approach''. UK Oxford: BIOS Scientific Publishers. ISBN-10: 1-85996-252-1 | |||
| [[Talk:Lecture_-_Endocrine_Development#Endocrinology_-_An_Integrated_Approach|Detailed Table of Contents]] | [http://www.ncbi.nlm.nih.gov/books/NBK22 Bookshelf Link] | |||
* [http://www.ncbi.nlm.nih.gov/books/n/endocrin/A3/ Chapter 1. Principles of endocrinology] | * [http://www.ncbi.nlm.nih.gov/books/n/endocrin/A3/ Chapter 1. Principles of endocrinology] | ||
* [http://www.ncbi.nlm.nih.gov/books/n/endocrin/A43/ Chapter 2. The endocrine pancreas] | * [http://www.ncbi.nlm.nih.gov/books/n/endocrin/A43/ Chapter 2. The endocrine pancreas] | ||
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* [http://www.ncbi.nlm.nih.gov/books/n/endocrin/A1257/ Chapter 7. The pituitary gland] | * [http://www.ncbi.nlm.nih.gov/books/n/endocrin/A1257/ Chapter 7. The pituitary gland] | ||
* [http://www.ncbi.nlm.nih.gov/books/n/endocrin/A1527/ Chapter 8. Cardiovascular and renal endocrinology] | * [http://www.ncbi.nlm.nih.gov/books/n/endocrin/A1527/ Chapter 8. Cardiovascular and renal endocrinology] | ||
|- | |||
| [[File:Larsen's human embryology 5th ed.jpg|90px|left]] Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R., Francis-West, P.H. & Philippa H. (2015). Larsen's human embryology (5th ed.). New York; Edinburgh: Churchill Livingstone. | |||
UNSW students have full access to this textbook edition through [http://er.library.unsw.edu.au/er/cgi-bin/eraccess.cgi?url=http://www.unsw.eblib.com.wwwproxy0.library.unsw.edu.au/patron/FullRecord.aspx?p=2074524 UNSW Library subscription] (with student Zpass log-in). Note that most embryology textbooks do no have specific chapter for endocrine development and this information is often found in other chapters (neural, renal, head, genital). | |||
| | |||
* Chapter 9 [http://ebookcentral.proquest.com.wwwproxy1.library.unsw.edu.au/lib/unsw/reader.action?docID=2074524&ppg=235 Development of the Hypothalamus] | |||
* Chapter 9 [http://ebookcentral.proquest.com.wwwproxy1.library.unsw.edu.au/lib/unsw/reader.action?docID=2074524&ppg=236 Development of the Pineal Gland] | |||
* Chapter 9 [http://ebookcentral.proquest.com.wwwproxy1.library.unsw.edu.au/lib/unsw/reader.action?docID=2074524&ppg=243 Development of the Pituitary] | |||
* Chapter 14 [http://ebookcentral.proquest.com.wwwproxy1.library.unsw.edu.au/lib/unsw/reader.action?docID=2074524&ppg=371 Development of the Pancreas] | |||
* Chapter 15 [http://ebookcentral.proquest.com.wwwproxy1.library.unsw.edu.au/lib/unsw/reader.action?docID=2074524&ppg=407 Development of the Suprarenal Gland] | |||
* Chapter 16 [http://ebookcentral.proquest.com.wwwproxy1.library.unsw.edu.au/lib/unsw/reader.action?docID=2074524&ppg=417 Development of the Gonad] | |||
* Chapter 17 [http://ebookcentral.proquest.com.wwwproxy1.library.unsw.edu.au/lib/unsw/reader.action?docID=2074524&ppg=479 Development of the Thyroid] | |||
{{UNSW textbook - Larsen's Human Embryology}} | |||
{{UNSW textbook - The Developing Human}} | |||
|} | |||
{| class="wikitable mw-collapsible mw-collapsed" | |||
! 2016 Lecture Video Recording | |||
|- | |- | ||
| | | This 2016 lecture video recording is similar in content to the current 2017 online lecture. | ||
<html5media height="600" width="800">File:2016Lecture-Endocrine.mp4</html5media> | |||
Click to play new window - [[Media:2016Lecture-Endocrine.mp4|'''2016 Lecture Video''']] (48 MB) | |||
|} | |} | ||
==Endocrine Origins== | |||
* '''Epithelia''' - (ectoderm) covering embryo, (endoderm) lining gastrointestinal tract, (mesoderm) lining coelomic cavity | |||
* '''Mesenchyme''' - (mesoderm) contribution, connective tissue, blood vessels | |||
==Hormones== | ==Hormones== | ||
[[File:Steroid hormone receptor signaling.jpg|thumb|Steroid hormone receptor signaling | [[File:Steroid hormone receptor signaling.jpg|thumb|Steroid hormone receptor signaling{{#pmid:17464358|PMID17464358}}]] | ||
===Hormone Types=== | ===Hormone Types=== | ||
* '''Amino acid derivatives''' - noradrenaline (norepinepherine), adrenalin (epinepherine) , thyroid hormone | * '''Amino acid derivatives''' - noradrenaline (norepinepherine), adrenalin (epinepherine) , thyroid hormone | ||
* '''Proteins, peptides''' - thyroid stimulating hormone, leutenising hormone, follicle stimulating hormone | * '''Proteins, peptides''' - thyroid stimulating hormone, leutenising hormone, follicle stimulating hormone | ||
* '''Steroids''' - androgens, glucocorticoids, mineralocorticoids | * '''Steroids''' - androgens, glucocorticoids, mineralocorticoids | ||
[[File:Steroid biosynthesis pathway.png|600px]] | |||
Steroid biosynthesis pathway | |||
===Hormone Actions=== | ===Hormone Actions=== | ||
* '''Autocrine''' - acts on self (extracellular fluid) | |||
* '''Paracrine''' - acts locally (extracellular fluid) | |||
* '''Autocrine''' - acts on self (extracellular fluid) | * '''Endocrine''' - acts by secretion into blood stream (endocrine organs are richly vascularized) | ||
* '''Paracrine''' - acts locally (extracellular fluid | |||
* '''Endocrine''' - acts by secretion into blood stream (endocrine organs are richly vascularized) | |||
===Hormone Receptors=== | ===Hormone Receptors=== | ||
* '''Cell surface receptors''' - modified amino acids, peptides, proteins | |||
* '''Cytoplasmic/Nuclear Receptors''' - steroids | |||
:Interested in hormone history? Listen ABC Radio Ockham's Razor 2005-07-31 6.2 Mb mp3 [http://embryology.med.unsw.edu.au/Podcast/OckhamRazor/CentenaryofHormone.mp3 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. | |||
==Pineal Gland== | ==Pineal Gland== | ||
[[File:pineal-body.jpg| | {| | ||
[[File:Pineal gland position.jpg| | | [[File:Keith1902 fig167.jpg|600px]] | ||
| valign=top|'''Pineal Development''' | |||
* part of | * '''Neuroectoderm''' - prosenecephalon then diencephalon | ||
* pinealocytes secrete melatonin - cyclic nature of activity, melatonin lowest during daylight | ** caudal roof, median diverticulum, epiphysis | ||
** inhibit hypothalamic secretion of GnRH until puberty, pineal gland then rapidly regresses. | * Initially a hollow diverticulum, cell proliferation to solid, pinealocytes (neuroglia), cone-shaped gland innervated by epithalamus | ||
|} | |||
{| | |||
| [[File:pineal-body.jpg|300px|Adult pineal body]] | |||
| [[File:Pineal gland position.jpg|300px|Pineal gland position]] | |||
|- | |||
| Adult pineal body | |||
| Pineal gland position | |||
|- | |||
| col width=300px| | |||
* part of '''epithalamus''' - neurons, glia and pinealocytes | |||
* '''pinealocytes''' secrete melatonin - cyclic nature of activity, melatonin lowest during daylight | |||
* maternal melatonin crosses the placental barrier | |||
* inhibit hypothalamic secretion of GnRH until puberty, pineal gland then rapidly regresses. | |||
* other activities - possibly gamete maturation, antioxidant effect, protect neurons? | * other activities - possibly gamete maturation, antioxidant effect, protect neurons? | ||
| [[File:Pineal_histology_001.jpg|300px]] | |||
|} | |||
{| | |||
| [[File:Fetal pineal gland 01.jpg|400px]] | |||
| valign=top|Fetal Pineal Anatomy{{#pmid:24757681|PMID24757681}} | |||
* Human fetus (3.5 month) superior (dorsal) view diencephalic-mesencephalic area. | |||
* | * Third ventricle (3 ventr) without pial covering is seen to the right. | ||
* | * Pineal gland is a small protuberance (arrow) and merging via the broad stalk with the habenula (Ha). Superior colliculus (Sup col.) | ||
* | |} | ||
:'''Links:''' {{Pineal}} | [[Talk:BGD_Lecture_-_Endocrine_Development#Chapter_7._The_pituitary_gland|Endocrinology]] | |||
==Hypothalamus== | ==Hypothalamus== | ||
[[File:Hypothalamus_histology_001.jpg|thumb|Adult hypothalamus]] | |||
'''Hormones''' - | '''Hormones''' - Corticotrophin releasing hormone (CRH), Thyrotrophin releasing hormone (TRH), Arginine vasopressin (AVP), Gonadotrophin releasing hormone (GnRH), Growth hormone releasing hormone (GHRH), Somatostatin, Prolactin relasing factor (PRF), Dopamine | ||
===Hypothalamus Development=== | ===Hypothalamus Development=== | ||
* Neuroectoderm - prosenecephalon then diencephalon | * Neuroectoderm - prosenecephalon then '''diencephalon''' | ||
* ventro-lateral wall intermediate zone proliferation | * ventro-lateral wall intermediate zone proliferation | ||
* Mamillary bodies - form pea-sized swellings ventral wall of hypothalamus | * Mamillary bodies - form pea-sized swellings ventral wall of hypothalamus | ||
{| | |||
|- | |||
| [[File:Stage_13_image_061.jpg|300px]] | |||
| [[File:Stage_22_image_055.jpg|300px]] | |||
|- | |||
| Week 5 Secondary Brain Vesicles - Stage 13|Diencephalon region, shown by [[O#optic stalk|optic stalk]]<br>([[Carnegie_stage_13|Stage 13]]) | |||
| Week 8 Embryo Brain - Stage 22|Late embryonic hypothalamus<br>([[Carnegie_stage_22|Stage 22]]) | |||
|} | |||
<gallery> | |||
File:Gray0651.jpg|Human Embryo Brain <br>(week 4.5 exterior view) | |||
File:Gray0652.jpg|Human Embryo Brain <br>(week 5 exterior view) | |||
File:Gray0653.jpg|Human Embryo Brain <br>(week 5 interior view) | |||
File:Gray0654.jpg|Human Fetal Brain <br>(3 months) | |||
File:Gray0655.jpg|Human Fetal Brain <br>(4 months) | |||
</gallery> | |||
:'''Links:''' [[Endocrine - Hypothalamus Development]] | :'''Links:''' [[Endocrine - Hypothalamus Development]] | ||
==Pituitary== | ==Pituitary== | ||
[[File: | {| | ||
[[File: | | [[File:Historic-pituitary.jpg|300px|Adult pituitary]] | ||
| [[File:Turkish saddle-17th century.jpg|150px|right|alt=Turkish saddle (17th century)]]The pituitary (hypophysis) sits anatomically within the sella turcica, a space within the sphenoid bone. | |||
'''Anterior pituitary hormones''' - Thyroid-stimulating hormone (TSH), Adrenocorticotrophic hormone (ACTH), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), Somatotrophin/growth hormone (GH), Prolactin (PRL), Melanocyte-stimulating hormone (MSH) | '''Anterior pituitary hormones''' - Thyroid-stimulating hormone (TSH), Adrenocorticotrophic hormone (ACTH), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), Somatotrophin/growth hormone (GH), Prolactin (PRL), Melanocyte-stimulating hormone (MSH) | ||
'''Posterior pituitary hormones''' - Oxytocin, Arginine vasopressin | '''Posterior pituitary hormones''' - Oxytocin, Arginine vasopressin | ||
|} | |||
===Pituitary Development=== | ===Pituitary Development=== | ||
[[File: | {| | ||
| [[File:Keith1902 fig015a.jpg|400px]] | |||
| [[File:Pituitary rabbit development.jpg|400px]] | |||
|} | |||
{| | {| | ||
| [[File:Pituitary development animation.gif]] | | [[File:Pituitary development animation.gif]] | ||
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* Dual ectoderm origins | * Dual ectoderm origins | ||
** Ectoderm - ectoderm roof of stomodeum, Rathke's pouch, adenohypophysis | ** '''Ectoderm''' - ectoderm roof of stomodeum, Rathke's pouch, adenohypophysis | ||
** Neuroectoderm - prosenecephalon then diencephalon, neurohypophysis | ** '''Neuroectoderm''' - prosenecephalon then diencephalon, neurohypophysis | ||
'''Adenohypophysis''' | '''Adenohypophysis''' | ||
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* Infundibulum – median eminence, infundibulum, pars nervosa | * Infundibulum – median eminence, infundibulum, pars nervosa | ||
[[File:Embryonic_and_fetal_pituitary.jpg]]<br> | |||
[[File:Stage_22_image_220.jpg|400px]] | |||
===Pituitary Timeline=== | ===Pituitary Timeline=== | ||
[[File:Fetal_head_section_03.jpg|thumb|Early Fetal (week 12)]] | |||
* '''Week 4''' - hypophysial pouch, Rathke’s pouch, diverticulum from roof | * '''Week 4''' - hypophysial pouch, Rathke’s pouch, diverticulum from roof | ||
* '''Week 5''' - elongation, contacts infundibulum, diverticulum of diencephalon | * '''Week 5''' - elongation, contacts infundibulum, diverticulum of diencephalon | ||
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:'''Links:''' | :'''Links:''' {{Pituitary}} | [http://www.med.unc.edu/embryo_images/unit-nervous/nerv_htms/nerv016.htm Embryo Images - Pituitary] | [[Talk:BGD_Lecture_-_Endocrine_Development#Chapter_7._The_pituitary_gland|Endocrinology]] | ||
==Thyroid== | ==Thyroid== | ||
[[File: | [[File:HPT axis.jpg|thumb|Hypothalamus - Pituitary - Thyroid Axis]] | ||
* '''Maternal thyroid hormone''' - required for early stages of brain development | |||
* '''Fetal thyroid''' - begins function from week10, ({{GA}} week 12) required for neural development, stimulates metabolism (protein, carbohydrate, lipid), reduced/absence = cretinism (see abnormalities) | |||
* | |||
'''Hormones''' - (amino acid derivatives) Thyroxine (T4), Triiodothyronine (T3) | '''Hormones''' - TH (amino acid derivatives) Thyroxine (T4), Triiodothyronine (T3) | ||
===Thyroid Development=== | ===Thyroid Development=== | ||
* thyroid median endodermal thickening in the floor of pharynx, outpouch – thyroid diverticulum | {| | ||
* tongue grows, cells descend in neck | | [[File:Stage13 and 22 thyroid development a.jpg|250px|Stage 13 and Stage 22 thyroid development]] | ||
* thyroglossal duct - proximal end at the foramen | | [[File:Tongue1.png|250px|foramen caecum]] | ||
* thyroid diverticulum - hollow then solid, right and left lobes, central isthmus | | [[File:Thyroid-development-cartoon.jpg|250px|thyroid development]] | ||
|} | |||
* thyroid median endodermal thickening in the floor of pharynx, outpouch – '''thyroid diverticulum'''. | |||
* tongue grows, cells descend in neck. | |||
* thyroglossal duct - proximal end at the foramen caecum of tongue. | |||
* thyroid diverticulum - hollow then solid, right and left lobes, central isthmus. | |||
===Thyroid Timeline=== | ===Thyroid Timeline=== | ||
* 24 days - thyroid median endodermal thickening in the floor of pharynx, outpouch – thyroid diverticulum | * '''24 days''' - thyroid median endodermal thickening in the floor of pharynx, outpouch – thyroid diverticulum | ||
* Week 11 - colloid appearance in thyroid follicles, iodine and thyroid hormone (TH) synthesis | * '''Week 11''' - colloid appearance in thyroid follicles, iodine and thyroid hormone (TH) synthesis. Growth factors (insulin-like, epidermal) stimulates follicular growth. | ||
* '''Week 16 - 18''' - ({{GA}} 18-20 weeks) fully functional | |||
:'''Links:''' [http://www.ncbi.nlm.nih.gov/books/NBK28/box/A331/?report=objectonly Box 3.21 Embryology of the thyroid and parathyroid glands] | |||
===Fetal Thyroid Hormone=== | ===Fetal Thyroid Hormone=== | ||
* Initial secreted biologically inactivated by modification | |||
* Iodine deficiency- during this period, leads to neurological defects (cretinism) | * Initial secreted biologically inactivated by modification | ||
** serum thyroid hormone levels are relatively low and tissue concentration of thyroid hormone is modified by iodothyronine deiodinases | |||
* Iodine deficiency - during this period, leads to neurological defects (cretinism) | |||
* Late fetal secretion - develops brown fat | |||
* Birth - TSH levels increase, thyroxine (T3) and T4 levels increase to 24 h, then 5-7 days postnatal decline to normal levels | * Birth - TSH levels increase, thyroxine (T3) and T4 levels increase to 24 h, then 5-7 days postnatal decline to normal levels | ||
* Post-natal - TH required for bone development | |||
'''Maternal TH''' - iodine/thyroid status can affect development. | |||
* recent studies show that both high and low maternal thyroid hormone impact on neural development (PMID 26497402) | |||
:'''Links:''' {{Thyroid}} | [[Talk:BGD_Lecture_-_Endocrine_Development#Chapter_3._The_thyroid_gland|Endocrinology]] | | |||
==Parathyroid== | ==Parathyroid== | ||
{| | |||
| | |||
* Parathyroid Hormone - Increase calcium ions [Ca2+], stimulates osteoclasts, increase Ca GIT absorption (opposite effect to calcitonin) | * Parathyroid Hormone - Increase calcium ions [Ca2+], stimulates osteoclasts, increase Ca GIT absorption (opposite effect to calcitonin) | ||
* Adult Calcium and Phosphate - Daily turnover in human with dietary intake of 1000 mg/day | * Adult Calcium and Phosphate - Daily turnover in human with dietary intake of 1000 mg/day | ||
* secreted by chief cells | * secreted by chief cells | ||
Principal cells cords of cells | Principal cells cords of cells | ||
| [[File:Parathyroid adult.jpg|200px|alt=Parathyroid adult]] | |||
Adult Parathyroid | |||
|} | |||
===Parathyroid Development=== | ===Parathyroid Development=== | ||
{| | |||
| | |||
* Endoderm - third and fourth pharyngeal pouches, could also have ectoderm and neural crest | * Endoderm - third and fourth pharyngeal pouches, could also have ectoderm and neural crest | ||
** 3rd Pharyngeal Pouch - inferior parathyroid, initially descends with thymus | ** 3rd Pharyngeal Pouch - inferior parathyroid, initially descends with thymus | ||
** 4th Pharyngeal Pouch - superior parathyroid | ** 4th Pharyngeal Pouch - superior parathyroid | ||
* Week 6 - diverticulum elongate, hollow then solid, dorsal cell proliferation | * '''Week 6''' - diverticulum elongate, hollow then solid, dorsal cell proliferation | ||
* Fetal parathyroids - respond to calcium levels, fetal calcium levels higher than maternal | * Fetal parathyroids - respond to calcium levels, fetal calcium levels higher than maternal | ||
* parathyroid hormone - (PTH, parathormone or parathyrin) | |||
| [[File:Pharyngeal pouches.jpg|300px|alt=Pharyngeal pouches]] | |||
Pharyngeal pouches | |||
|} | |||
:'''Links:''' [[ | :'''Links:''' {{Parathyroid}} | [[Talk:BGD_Lecture_-_Endocrine_Development#Chapter_5._The_parathyroid_glands_and_vitamin_D|Endocrinology]] | ||
==Thymus== | ==Thymus== | ||
* Thymus - bone-marrow lymphocyte precursors become thymocytes, and subsequently mature into T lymphocytes (T cells) | * Thymus - bone-marrow lymphocyte precursors become thymocytes, and subsequently mature into T lymphocytes (T cells) | ||
* Thymus hormones - thymosins stimulate the development and differentiation of T lymphocytes | * Thymus hormones - thymosins stimulate the development and differentiation of T lymphocytes | ||
===Thymus Development=== | |||
{| | |||
| | |||
* Endoderm - third pharyngeal pouch | |||
* '''Week 6''' - diverticulum elongates, hollow then solid, ventral cell proliferation | |||
* '''Thymic primordia''' - surrounded by neural crest mesenchyme, epithelia/mesenchyme interaction | |||
* Postnatal - '''involution''', thymus regression after puberty. | |||
| [[File:Gray1178.jpg|300px]] | |||
Fetal Thymus | |||
|} | |||
:'''Links:''' {{Thymus}} | |||
==Pancreas== | ==Pancreas== | ||
{| | |||
| | |||
* Functions - exocrine (amylase, alpha-fetoprotein), 99% by volume; endocrine (pancreatic islets) 1% by volume | * Functions - exocrine (amylase, alpha-fetoprotein), 99% by volume; endocrine (pancreatic islets) 1% by volume | ||
* Exocrine function - begins after birth | * Exocrine function - begins after birth | ||
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** exact roles of hormones in regulating fetal growth? | ** exact roles of hormones in regulating fetal growth? | ||
[[File:Pancreas cartoon.jpg|300px|alt=pancreas structure]] | |||
| [[File:Pancreas adult.jpg|300px|alt=Pancreas adult]] | |||
|} | |||
===Pancreas Development=== | ===Pancreas Development=== | ||
* Pancreatic buds - duodenal level endoderm, splanchnic mesoderm forms dorsal and ventral mesentery, dorsal bud (larger, first), ventral bud (smaller, later) | * Pancreatic buds - duodenal level endoderm, splanchnic mesoderm forms dorsal and ventral mesentery, dorsal bud (larger, first), ventral bud (smaller, later) | ||
* Pancreas Endoderm - pancreas may be opposite of liver | * Pancreas Endoderm - pancreas may be opposite of liver | ||
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** Notochord may promote pancreas formation | ** Notochord may promote pancreas formation | ||
** Heart may block pancreas formation | ** Heart may block pancreas formation | ||
{| | |||
* Duodenum growth/rotation - brings ventral and dorsal buds together, fusion of buds | | [[File:Pancreatic_duct_developing.jpg|400px|alt=Pancreatic buds and duct developing]] | ||
| [[File:Stage22_pancreas_a.jpg|400px|alt=Stage 22 pancreas]] | |||
|- | |||
| Pancreatic buds and duct developing | |||
| Pancreas week 8 (Stage 22) | |||
|} | |||
* Duodenum growth/rotation - brings ventral and dorsal buds together, fusion of buds [http://www.ncbi.nlm.nih.gov/books/NBK30/box/A171/?report=objectonly See Figure 2.32] | |||
* Pancreatic duct - ventral bud duct and distal part of dorsal bud, exocrine function | * Pancreatic duct - ventral bud duct and distal part of dorsal bud, exocrine function | ||
* Islet cells - cords of endodermal cells form ducts, from which cells bud off to form islets | * Islet cells - cords of '''endodermal cells''' form ducts, from which cells bud off to form islets | ||
{| class="wikitable mw-collapsible mw-collapsed" | |||
! Islet | |||
|- | |||
| [[File:Pancreas histology 104.jpg|300px|left]] Arterial blood (from splenic, hepatic and superior mesenteric arteries) enters the core of each islet and capillaries then drain outwardly to the periphery where venous blood drains into the splenic and superior mesenteric veins. | |||
Histology image shows blood vessels injected with ink. | |||
|} | |||
===Pancreatic Islets=== | ===Pancreatic Islets=== | ||
* Islets of Langerhans - 4 endocrine cell types | * Islets of Langerhans - 4 endocrine cell types | ||
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===Pancreas Timeline=== | ===Pancreas Timeline=== | ||
* Week 7 to 20 - pancreatic hormones secretion increases, small amount maternal insulin | * '''Week 7 to 20''' - pancreatic hormones secretion increases, small amount maternal insulin | ||
* Week 10 - glucagon (alpha) differentiate first, somatostatin (delta), insulin (beta) cells differentiate, insulin secretion begins | * '''Week 10''' - glucagon (alpha) differentiate first, somatostatin (delta), insulin (beta) cells differentiate, insulin secretion begins | ||
* Week 15 - glucagon detectable in fetal plasma | * '''Week 15''' - glucagon detectable in fetal plasma | ||
:'''Links:''' [[Endocrine - Pancreas Development]] | [[Gastrointestinal Tract - Pancreas Development]] | :'''Links:''' [[Endocrine - Pancreas Development]] | [[Gastrointestinal Tract - Pancreas Development]] | [[Talk:BGD_Lecture_-_Endocrine_Development#Chapter_2._The_endocrine_pancreas|Endocrinology]] | ||
==Adrenal== | ==Adrenal== | ||
[[File:Week10 adrenal.jpg|thumb|Fetal adrenal gland (Week 10, {{GA}} week 12]] | |||
* Richly vascularized - arterioles passing through cortex, capillaries from cortex to medulla, portal-like circulation | * Richly vascularized - arterioles passing through cortex, capillaries from cortex to medulla, portal-like circulation | ||
* Fetal Cortex - produces a steroid precursor (DEA), converted by placenta into estrogen | * Fetal Cortex - produces a steroid precursor (DEA), converted by placenta into estrogen | ||
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===Adrenal Development=== | ===Adrenal Development=== | ||
[[File:Adrenal_medulla.jpg|300px|right|link= | [[File:Adrenal_medulla.jpg|300px|right|link=Adrenal Medulla Development Movie]] | ||
* '''Week 6''' - fetal cortex, from mesothelium adjacent to dorsal mesentery; Medulla, neural crest cells from adjacent sympathetic ganglia | |||
* Fetal Adrenals - fetal cortex later replaced by adult cortex | * Fetal Adrenals - fetal cortex later replaced by adult cortex | ||
* Adult cortex - mesothelium mesenchyme encloses fetal cortex | * Adult cortex - mesothelium mesenchyme encloses fetal cortex | ||
'''Adrenal Cortex''' | '''Adrenal Cortex''' | ||
* Late Fetal Period - differentiates to form cortical zones | * Late Fetal Period - differentiates to form cortical zones | ||
* Birth - zona glomerulosa, zona fasiculata present | * Birth - zona glomerulosa, zona fasiculata present | ||
* Year 3 - zona reticularis present | * Year 3 - zona reticularis present | ||
{| | |||
| | |||
'''Adrenal Medulla''' | '''Adrenal Medulla''' | ||
* neural crest origin, migrate adjacent to coelomic cavity, initially uncapsulated and not surrounded by fetal cortex, cells have neuron-like morphology | * neural crest origin, migrate adjacent to coelomic cavity, initially uncapsulated and not surrounded by fetal cortex, cells have neuron-like morphology | ||
* 2 cell types - secrete epinepherine (adrenaline) 80%; secrete norepinepherine (noradrenaline* 20% | * 2 cell types - secrete epinepherine (adrenaline) 80%; secrete norepinepherine (noradrenaline* 20% | ||
| valign="bottom"|{{Adrenal movie}} | |||
|} | |||
:'''Links:''' [ | :'''Links:''' {{Adrenal}} | [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=endocrin&part=A442&rendertype=box&id=A466 Endocrinology - Adrenal Cortex Development] | [[Talk:BGD_Lecture_-_Endocrine_Development#Chapter_4._The_adrenal_gland|Endocrinology]] | ||
==Gonad== | ==Gonad== | ||
[[File: | {| | ||
| [[File:HPG female axis.jpg|300px]] | |||
Adult Hypothalamus - Pituitary - Gonad (female) | |||
| [[File:HPG male axis.jpg|300px]] | |||
Adult Hypothalamus - Pituitary - Gonad (male) | |||
|} | |||
HPG Axis - [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=endocrin&part=A972&rendertype=box&id=A1057 Endocrinology - Simplified diagram of the actions of gonadotrophins] | HPG Axis - [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=endocrin&part=A972&rendertype=box&id=A1057 Endocrinology - Simplified diagram of the actions of gonadotrophins] | ||
===Gonad Development=== | ===Gonad Development=== | ||
-- | * '''mesoderm''' - mesothelium and underlying mesenchyme | ||
* '''Gonadal ridge''' - mesothelium thickening, medial mesonephros | |||
* '''Primordial Germ cells''' - yolk sac, to mesentery of hindgut, to genital ridge of developing kidney | |||
Differentiation | |||
* testis-determining factor (TDF) from Y chromosome: presence (testes), absence (ovaries) | * testis-determining factor (TDF) from Y chromosome: presence (testes), absence (ovaries) | ||
''' | ====Testis==== | ||
* '''8 Weeks''' - mesenchyme, interstitial cells (of Leydig) secrete testosterone, androstenedione. | |||
* 8 to 12 Weeks - hCG stimulates testosterone production | * '''8 to 12 Weeks''' - hCG stimulates testosterone production (required for male genital development) | ||
* Sustentacular cells - produce anti-mullerian hormone to puberty | * Sustentacular (Sertoli) cells - produce anti-mullerian hormone (AMH) to puberty. | ||
** '''AMH''' - anti-Müllerian hormone (Müllerian inhibiting factor (MIF), Müllerian-inhibiting hormone (MIH), and Müllerian-inhibiting substance (MIS)). | |||
[[File:Male_testosterone_and_AMH_level_graph.jpg|500px]] | |||
====Ovary==== | |||
[[File:Infant_ovary.jpg|thumb|Infant Ovary]] | |||
* X chromosome genes regulate ovary development | * X chromosome genes regulate ovary development | ||
* Hormone levels increase at puberty with follicle development. | |||
I covered this topic in detail in sexual differentiation lecture/practical. | |||
:'''Links:''' [[Endocrine - Gonad Development]] | :'''Links:''' [[Endocrine - Gonad Development]] | [[Talk:BGD_Lecture_-_Endocrine_Development#Chapter_6._The_gonad|Endocrinology]] | ||
==Placenta== | ==Placenta== | ||
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:'''Links:''' [[Endocrine - Placenta Development]] | :'''Links:''' [[Endocrine - Placenta Development]] | ||
==Other Endocrine== | ==Other Endocrine== | ||
===Endocrine Heart=== | ===Endocrine Heart=== | ||
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* Adiponectin - regulation of energy homeostasis and glucose and lipid metabolism, as well as acting as an anti-inflammatory on the cellular vascular wall | * Adiponectin - regulation of energy homeostasis and glucose and lipid metabolism, as well as acting as an anti-inflammatory on the cellular vascular wall | ||
* Resistin - (for resistance to insulin, RETN) a 108 amino acid polypeptide and the related resistin-like protein-beta (Resistin-like molecule-beta, RELMbeta) stimulate endogenous glucose production | * Resistin - (for resistance to insulin, RETN) a 108 amino acid polypeptide and the related resistin-like protein-beta (Resistin-like molecule-beta, RELMbeta) stimulate endogenous glucose production | ||
:'''Links:''' [[Endocrine - Other Tissues]] | :'''Links:''' [[Endocrine - Other Tissues]] | ||
==Endocrine Functional Changes== | ==Endocrine Functional Changes== | ||
* Puberty- Increased activity | * '''Puberty''' - Increased activity. | ||
* Menopause- Decreased activity | * '''Menopause''' - Decreased activity. | ||
* Disease (diabetes, thyroid, kidney) suggested trends that genetics, health, nutrition, lifestyle may influence time that these events occur | * '''Disease''' - (diabetes, thyroid, kidney) suggested trends that genetics, health, nutrition, lifestyle may influence time that these events occur. | ||
* Pharmaceutical impact - birth control, steroids, Hormone Replacement Therapy (HRT) | * '''Pharmaceutical impact''' - birth control, steroids, Hormone Replacement Therapy (HRT). | ||
==Abnormalities== | ==Abnormalities== | ||
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* pituitary tumours (adenomas) - several abnormalities associated with abnormal levels of the hormonal output of the pituitary. | * pituitary tumours (adenomas) - several abnormalities associated with abnormal levels of the hormonal output of the pituitary. | ||
** Growth hormone (GH) adenomas - benign pituitary tumors lead to chronic high GH output levels, that may lead to acromegaly. | ** Growth hormone (GH) adenomas - benign pituitary tumors lead to chronic high GH output levels, that may lead to acromegaly. | ||
* Cushing's disease - caused either by a pituitary adenoma produces excess adrenocorticotropic hormone (ACTH, corticotropin) or due to ectopic tumors secreting ACTH or corticotropin-releasing hormone (CRH). | * '''Cushing's disease''' - caused either by a pituitary adenoma produces excess adrenocorticotropic hormone (ACTH, corticotropin) or due to ectopic tumors secreting ACTH or corticotropin-releasing hormone (CRH). | ||
=== Thyroid === | === Thyroid === | ||
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===Parathyroid=== | ===Parathyroid=== | ||
* Usually four glands are present (2 on each side), but three to six glands have been found in human. | * Usually four glands are present (2 on each side), but three to six glands have been found in human. | ||
* Can have displaced parathyroid development with thymus. | |||
* Lower parathyroid glands arise from the third pharyngeal pouch and descend with the thymus. Variable descent can lead to a range of adult locations, from just beneath the mandible to the anterior mediastinum. | * Lower parathyroid glands arise from the third pharyngeal pouch and descend with the thymus. Variable descent can lead to a range of adult locations, from just beneath the mandible to the anterior mediastinum. | ||
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===Endocrine Disruptors=== | ===Endocrine Disruptors=== | ||
[[File:Diethylstilbestrol.jpg|thumb|Diethylstilbestrol]] | |||
Exogenous chemicals that interfere with the function of hormones. There are 3 main mechanisms: mimic, block or interfere. | Exogenous chemicals that interfere with the function of hormones. There are 3 main mechanisms: mimic, block or interfere. | ||
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* Polychlorinated biphenyl pollutants - (PCBs) Rats exposed to PCBs have low levels of thyroid hormone. Compete for binding sites of thyroid hormone transport protein. Without being bound to this protein, thyroid hormones are excreted from the body (McKinney et al. 1985; Morse et al. 1996) | * Polychlorinated biphenyl pollutants - (PCBs) Rats exposed to PCBs have low levels of thyroid hormone. Compete for binding sites of thyroid hormone transport protein. Without being bound to this protein, thyroid hormones are excreted from the body (McKinney et al. 1985; Morse et al. 1996) | ||
:Links: | |||
==References== | ==References== | ||
<references/> | <references/> | ||
* Endocrinology: An Integrated Approach Nussey, S.S. and Whitehead, S.A. London:Taylor & Francis; c2001 [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=endocrin&part=A3&rendertype=box&id=A11 Major hormone types] | * '''Endocrinology: An Integrated Approach''' Nussey, S.S. and Whitehead, S.A. London:Taylor & Francis; c2001 [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=endocrin&part=A3&rendertype=box&id=A11 Major hormone types] | ||
* Genes and Disease, Bethesda (MD): National Library of Medicine (US), NCBI [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gnd.chapter.41 Chapter 41 - Glands and Hormones] | * '''Genes and Disease''', Bethesda (MD): National Library of Medicine (US), NCBI [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gnd.chapter.41 Chapter 41 - Glands and Hormones] | ||
===Search === | ===Search === | ||
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==Terms== | ==Terms== | ||
{{Endocrine terms}} | |||
{{2018ANAT2341}} | |||
[[Category:Endocrine]] [[Category:Adrenal]] [[Category:Thyroid]] [[Category:Parathyroid]] [[Category:Pituitary]] [[Category:Pancreas]] [[Category:Genital]] | [[Category:Endocrine]] [[Category:Adrenal]] [[Category:Thyroid]] [[Category:Parathyroid]] [[Category:Pituitary]] [[Category:Pancreas]] [[Category:Genital]] | ||
Latest revision as of 09:48, 4 September 2018
Introduction
The endocrine system resides within specific endocrine organs and both organs and tissues with other specific functions. Epithelia (ectoderm and endoderm) form the majority of the “ductless” endocrine glands like gastrointestinal and skin associated “ducted” glands. Differentiation of several also organs involves a epithelial/mesenchye interaction, seen in repeated in many differentiation of many different tissues. The endocrine glands produce hormones, which are distributed by the vascular system to the many body tissues, subsequently these organs are richly vascularized.
Hormones “orchestrate” responses in other tissues, including other endocrine organs, and these overall effects can be similar or different in different tissues. These signaling pathways are often described as "axes" the two major types are the: HPA (Hypothalamus-Pituitary-Adrenal) and HPG (Hypothalamus-Pituitary-Gonad). These hormone effects (like music) can be rapid, slow, brief, diurnal, or long-term. Hormone effects can be mimicked, stimulated, and blocked by therapeutic drugs, nutritional and environmental chemicals. Importantly, fetal endocrine development is required for normal fetal growth and differentiation.
Lecture Objectives
- Understanding of hormone types
- Understanding of endocrine gland development
- Understanding of endocrine developmental functions
Endocrine in the News |
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Implanted in the intraperitoneal space of mice treated to chemically induce type 1 diabetes. Implants induced glycemic correction without any immunosuppression until their removal at 174 d after implantation. Human C-peptide concentrations and in vivo glucose responsiveness demonstrated therapeutically relevant glycemic control and retrieved implants contained viable insulin-producing cells. |
Oral Contraceptives A recent 2016 Danish study births from Danish registries between 1997 and 2011 identified that:
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Ernest Henry Starling (1866-1927)
<html5media>File:Audio - centenary of hormone.mp3</html5media> |
Lecture Resources
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2016 Lecture Video Recording |
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This 2016 lecture video recording is similar in content to the current 2017 online lecture.
<html5media height="600" width="800">File:2016Lecture-Endocrine.mp4</html5media> Click to play new window - 2016 Lecture Video (48 MB) |
Endocrine Origins
- Epithelia - (ectoderm) covering embryo, (endoderm) lining gastrointestinal tract, (mesoderm) lining coelomic cavity
- Mesenchyme - (mesoderm) contribution, connective tissue, blood vessels
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
Steroid biosynthesis pathway
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
- Interested in hormone history? Listen ABC Radio Ockham's Razor 2005-07-31 6.2 Mb mp3 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.
Pineal Gland
Pineal Development
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Adult pineal body | Pineal gland position |
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Fetal Pineal Anatomy[2]
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- Links: pineal | Endocrinology
Hypothalamus
Hormones - Corticotrophin releasing hormone (CRH), Thyrotrophin releasing hormone (TRH), Arginine vasopressin (AVP), Gonadotrophin releasing hormone (GnRH), Growth hormone releasing hormone (GHRH), Somatostatin, Prolactin relasing factor (PRF), Dopamine
Hypothalamus Development
- Neuroectoderm - prosenecephalon then diencephalon
- ventro-lateral wall intermediate zone proliferation
- Mamillary bodies - form pea-sized swellings ventral wall of hypothalamus
Diencephalon region, shown by optic stalk (Stage 13) |
Late embryonic hypothalamus (Stage 22) |
Pituitary
The pituitary (hypophysis) sits anatomically within the sella turcica, a space within the sphenoid bone.
Anterior pituitary hormones - Thyroid-stimulating hormone (TSH), Adrenocorticotrophic hormone (ACTH), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), Somatotrophin/growth hormone (GH), Prolactin (PRL), Melanocyte-stimulating hormone (MSH) Posterior pituitary hormones - Oxytocin, Arginine vasopressin |
Pituitary Development
Blue - neural tube ectoderm
Red - surface ectoderm |
- Dual ectoderm origins
- Ectoderm - ectoderm roof of stomodeum, Rathke's pouch, adenohypophysis
- Neuroectoderm - prosenecephalon then diencephalon, neurohypophysis
Adenohypophysis
- Anterior wall proliferates - pars distalis
- Posterior wall little growth – pars intermedia
- Rostral growth around infundibular stem – pars tuberalis
Neurohypophysis
- Infundibulum – median eminence, infundibulum, pars nervosa
Pituitary Timeline
- Week 4 - hypophysial pouch, Rathke’s pouch, diverticulum from roof
- Week 5 - elongation, contacts infundibulum, diverticulum of diencephalon
- Week 6 - connecting stalk between pouch and oral cavity degenerates
- Week 8 - basophilic staining cells appear
- Week 9 - acidophilic staining cells appear
- Week 10 - growth hormone and ACTH detectable
- Week 16 - adenohypophysis fully differentiated and TSH increases to peak at 22 weeks
- Week 20 to 24 - growth hormone levels peak, then decline
- Birth - second TSH surge and decreases postnatally
- Links: pituitary | Embryo Images - Pituitary | Endocrinology
Thyroid
- Maternal thyroid hormone - required for early stages of brain development
- Fetal thyroid - begins function from week10, (GA week 12) required for neural development, stimulates metabolism (protein, carbohydrate, lipid), reduced/absence = cretinism (see abnormalities)
Hormones - TH (amino acid derivatives) Thyroxine (T4), Triiodothyronine (T3)
Thyroid Development
- thyroid median endodermal thickening in the floor of pharynx, outpouch – thyroid diverticulum.
- tongue grows, cells descend in neck.
- thyroglossal duct - proximal end at the foramen caecum of tongue.
- thyroid diverticulum - hollow then solid, right and left lobes, central isthmus.
Thyroid Timeline
- 24 days - thyroid median endodermal thickening in the floor of pharynx, outpouch – thyroid diverticulum
- Week 11 - colloid appearance in thyroid follicles, iodine and thyroid hormone (TH) synthesis. Growth factors (insulin-like, epidermal) stimulates follicular growth.
- Week 16 - 18 - (GA 18-20 weeks) fully functional
Fetal Thyroid Hormone
- Initial secreted biologically inactivated by modification
- serum thyroid hormone levels are relatively low and tissue concentration of thyroid hormone is modified by iodothyronine deiodinases
- Iodine deficiency - during this period, leads to neurological defects (cretinism)
- Late fetal secretion - develops brown fat
- Birth - TSH levels increase, thyroxine (T3) and T4 levels increase to 24 h, then 5-7 days postnatal decline to normal levels
- Post-natal - TH required for bone development
Maternal TH - iodine/thyroid status can affect development.
- recent studies show that both high and low maternal thyroid hormone impact on neural development (PMID 26497402)
- Links: thyroid | Endocrinology |
Parathyroid
Principal cells cords of cells |
Adult Parathyroid |
Parathyroid Development
|
Pharyngeal pouches |
- Links: parathyroid | Endocrinology
Thymus
- Thymus - bone-marrow lymphocyte precursors become thymocytes, and subsequently mature into T lymphocytes (T cells)
- Thymus hormones - thymosins stimulate the development and differentiation of T lymphocytes
Thymus Development
|
Fetal Thymus |
- Links: thymus
Pancreas
|
Pancreas Development
- Pancreatic buds - duodenal level endoderm, splanchnic mesoderm forms dorsal and ventral mesentery, dorsal bud (larger, first), ventral bud (smaller, later)
- Pancreas Endoderm - pancreas may be opposite of liver
- Heart cells promote/notochord prevents liver formation
- Notochord may promote pancreas formation
- Heart may block pancreas formation
Pancreatic buds and duct developing | Pancreas week 8 (Stage 22) |
- Duodenum growth/rotation - brings ventral and dorsal buds together, fusion of buds See Figure 2.32
- Pancreatic duct - ventral bud duct and distal part of dorsal bud, exocrine function
- Islet cells - cords of endodermal cells form ducts, from which cells bud off to form islets
Islet |
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Arterial blood (from splenic, hepatic and superior mesenteric arteries) enters the core of each islet and capillaries then drain outwardly to the periphery where venous blood drains into the splenic and superior mesenteric veins.
Histology image shows blood vessels injected with ink. |
Pancreatic Islets
- Islets of Langerhans - 4 endocrine cell types
- Alpha - glucagon, mobilizes lipid
- Beta - insulin, increase glucose uptake
- Beta cells, stimulate fetal growth, continue to proliferate to postnatal, in infancy most abundant
- Delta - somatostatin, inhibits glucagon, insulin secretion
- F-cells - pancreatic polypeptide
Pancreas Timeline
- Week 7 to 20 - pancreatic hormones secretion increases, small amount maternal insulin
- Week 10 - glucagon (alpha) differentiate first, somatostatin (delta), insulin (beta) cells differentiate, insulin secretion begins
- Week 15 - glucagon detectable in fetal plasma
- Links: Endocrine - Pancreas Development | Gastrointestinal Tract - Pancreas Development | Endocrinology
Adrenal
- Richly vascularized - arterioles passing through cortex, capillaries from cortex to medulla, portal-like circulation
- Fetal Cortex - produces a steroid precursor (DEA), converted by placenta into estrogen
- Adult Medulla - produces adrenalin (epinephrine), noradrenaline (norepinephrine)
- Fetal adrenal hormones - influence lung maturation
Adrenal cortical hormones - (steroids) Cortisol, Aldosterone, Dehydroepiandrosterone
- zona glomerulosa - regulated by renin-angiotensin-aldosterone system controlled by the juxtaglomerular apparatus of the kidney.
- zona fasciculata - regulated by hypothalamo-pituitary axis with the release of CRH and ACTH respectively.
Adrenal medullary hormones - (amino acid derivatives) Epinephrine, Norepinephrine
Adrenal Development
- Week 6 - fetal cortex, from mesothelium adjacent to dorsal mesentery; Medulla, neural crest cells from adjacent sympathetic ganglia
- Fetal Adrenals - fetal cortex later replaced by adult cortex
- Adult cortex - mesothelium mesenchyme encloses fetal cortex
Adrenal Cortex
- Late Fetal Period - differentiates to form cortical zones
- Birth - zona glomerulosa, zona fasiculata present
- Year 3 - zona reticularis present
Adrenal Medulla
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Gonad
Adult Hypothalamus - Pituitary - Gonad (female) |
Adult Hypothalamus - Pituitary - Gonad (male) |
HPG Axis - Endocrinology - Simplified diagram of the actions of gonadotrophins
Gonad Development
- mesoderm - mesothelium and underlying mesenchyme
- Gonadal ridge - mesothelium thickening, medial mesonephros
- Primordial Germ cells - yolk sac, to mesentery of hindgut, to genital ridge of developing kidney
Differentiation
- testis-determining factor (TDF) from Y chromosome: presence (testes), absence (ovaries)
Testis
- 8 Weeks - mesenchyme, interstitial cells (of Leydig) secrete testosterone, androstenedione.
- 8 to 12 Weeks - hCG stimulates testosterone production (required for male genital development)
- Sustentacular (Sertoli) cells - produce anti-mullerian hormone (AMH) to puberty.
- AMH - anti-Müllerian hormone (Müllerian inhibiting factor (MIF), Müllerian-inhibiting hormone (MIH), and Müllerian-inhibiting substance (MIS)).
Ovary
- X chromosome genes regulate ovary development
- Hormone levels increase at puberty with follicle development.
I covered this topic in detail in sexual differentiation lecture/practical.
Placenta
- Human chorionic gonadotrophin (hCG) - like leutenizing hormone, supports corpus luteum in ovary, pregnant state rather than menstrual, maternal urine in some pregnancy testing
- Human chorionic somatommotropin (hCS) - or placental lactogen stimulate (maternal) mammary development
- Human chorionic thyrotropin (hCT)
- Human chorionic corticotropin (hCACTH)
- progesterone and estrogens - support maternal endometrium
- Relaxin
- Placenta - Maternal (decidua) and Fetal (trophoblastic cells, extraembryonic mesoderm) components
- Endocrine function - maternal and fetal precursors, synthesis and secretion
- Protein Hormones - chorionic gonadotropin (hCG), chorionic somatomammotropin (hCS) or placental lactogen (hPL), chorionic thyrotropin (hCT), chorionic corticotropin (hCACTH)
- hCG - up to 20 weeks, fetal adrenal cortex growth and maintenance
- hCS – rise through pregnancy, stimulates maternal metabolic processes, breast growth
- Steroid Hormones - progesterone (maintains pregnancy), estrogens (fetal adrenal/placenta)
- Protein Hormones - chorionic gonadotropin (hCG), chorionic somatomammotropin (hCS) or placental lactogen (hPL), chorionic thyrotropin (hCT), chorionic corticotropin (hCACTH)
Other Endocrine
Endocrine Heart
- Atrial natriuretic peptide (ANP) - Increase Filtration rate / decrease Na+ reabsorption
- Endothelins - ET-1, ET-2, ET-3, Vasoconstriction / Increase NO
- Nitric oxide (NO) - Vasodilatation
Endocrine Kidney
- Renin - Increase Angiotensin-aldosterone system
- Prostaglandins - decrease Na+ reabsorption
- Erythropoietin - Increase Erythrocyte (rbc) production
- 1,25 (OH)2 vitamin D - calcium homeostasis
- Prekallikreins - Increase Kinin production
GIT Endocrine
Enteric control of digestive function
- Gastrin - Secreted from stomach (G cells), role in control of gastric acid secretion
- Cholecystokinin - small intestine hormone, stimulates secretion of pancreatic enzymes and bile
- Secretin - small intestine hormone (epithelial cells), stimulates secretion of bicarbonate-rich fluids from pancreas and liver
Adipose Tissue
- Leptin - polypeptide hormone produced in adipose and many other tissues with also many different roles
- Adiponectin - regulation of energy homeostasis and glucose and lipid metabolism, as well as acting as an anti-inflammatory on the cellular vascular wall
- Resistin - (for resistance to insulin, RETN) a 108 amino acid polypeptide and the related resistin-like protein-beta (Resistin-like molecule-beta, RELMbeta) stimulate endogenous glucose production
- Links: Endocrine - Other Tissues
Endocrine Functional Changes
- Puberty - Increased activity.
- Menopause - Decreased activity.
- Disease - (diabetes, thyroid, kidney) suggested trends that genetics, health, nutrition, lifestyle may influence time that these events occur.
- Pharmaceutical impact - birth control, steroids, Hormone Replacement Therapy (HRT).
Abnormalities
NIH Genes & Disease Chapter 41 - Glands and Hormones
Pineal
- hypoplasia - associated with retinal disease.
- tumours - in children are associated with abnormal puberty development.
Pituitary
- craniopharyngeal canal - Rathke's pouch abnormality, from the anterior part of the fossa hypophyseos of the sphenoid bone to the under surface of the skull.
- pituitary tumours (adenomas) - several abnormalities associated with abnormal levels of the hormonal output of the pituitary.
- Growth hormone (GH) adenomas - benign pituitary tumors lead to chronic high GH output levels, that may lead to acromegaly.
- Cushing's disease - caused either by a pituitary adenoma produces excess adrenocorticotropic hormone (ACTH, corticotropin) or due to ectopic tumors secreting ACTH or corticotropin-releasing hormone (CRH).
Thyroid
- Pyramidal lobe - from isthmus (50% of people) attached to hyoid bone distal end of thryoglossal duct.
- Congenital hypothyroidism - approximately 1 in 3000 births, associated with neurological abnormalities.
- Lingual thyroid gland - failure of thyroid descent.
- Thyroglossal cyst - persistance of thyroglossal duct. Image - thyroglossal duct
- Thyroglossal fistula - partial degeneration of the thyroglossal duct.
- Abnormal development of the thyroid - incomplete or excessive descent.
- Childhood hypothyroidism delays ossification and bone mineralization.
Iodine Deficiency
- A teaspoon of iodine, total lifetime requirement, cannot be stored for long periods by our body, tiny amounts are needed regularly
- Areas of endemic iodine deficiency, where soil and therefore crops and grazing animals do not provide sufficient dietary iodine to the populace
- food fortification and supplementation - Iodized salt programs and iodized oil supplements are the most common tools in fight against IDD
Parathyroid
- Usually four glands are present (2 on each side), but three to six glands have been found in human.
- Can have displaced parathyroid development with thymus.
- Lower parathyroid glands arise from the third pharyngeal pouch and descend with the thymus. Variable descent can lead to a range of adult locations, from just beneath the mandible to the anterior mediastinum.
Pancreas
- Type 1 Diabetes - juvenile onset diabetes, more severe form of illness, increases risk of blindness, heart disease, kidney failure, neurological disease, T-lymphocyte-dependent autoimmune disease, infiltration and destruction of the islets of Langerhans, Approx 16 million Americans
- Type 2 Diabetes - loosely defined as "adult onset" diabetes, becoming more common cases of type 2 diabetes seen in younger people
- Risk of developing diabetes - environmental factors (food intake and exercise play an important role, either overweight or obese), Inherited factors (genes involved remain poorly defined)
Adrenal
- Congenital Adrenal Hyperplasia (CAH) - family of inherited disorders of adrenal steroidogenesis enzymes which impairs cortisol production by the adrenal cortex. Androgen excess leads newborn females with external genital ambiguity and postnatal progressive virilization in both sexes.
- Enzymes most commonly affected: 21-hydroxylase (21-OH), 11beta-hydroxylase, 3beta-hydroxysteroid dehydrogenase.
- Enzymes less commonly affected: 17alpha-hydroxylase/17,20-lyase and cholesterol desmolase.
- Pheochromocytomas (PCC) - Catecholamine-producing (neuro)endocrine tumor located in the adrenal medulla. Similar catecholamine-producing tumors outside the adrenal gland are called paragangliomas (PGL).
Endocrine Disruptors
Exogenous chemicals that interfere with the function of hormones. There are 3 main mechanisms: mimic, block or interfere.
Mimic - effects of natural hormones by binding receptors
- Diethylstilbestrol - (DES or diethylstilbetrol) a drug prescribed to women from 1938-1971 to prevent miscarriage in high-risk pregnancies. Acts as a potent estrogen (mimics natural hormone) and therefore a potential endocrine disruptor. Female fetus, increased risk abnormal reproductive tract and cancer. Male fetus, abnormal genitalia. Banned by USA FDA in 1979 as a teratogen, previously used as livestock growth promoter.
Block - binding of a hormone to receptor or hormone synthesis
- Finasteride - chemical used to prevent male pattern baldness and enlargement of prostate glands. An anti-androgen (blocks synthesis of dihydrotestosterone) and therefore a potential endocrine disruptor, exposed pregnant women can impact on male fetus genetial development.
- Vinclozolin - a dicarboximide fungicide, perinatal exposure in rats inhibits morphological sex differentiation. In adult rats, shown to cause gonad tumours (Leydig cell) and atrophy. Chemical has androgen-antagonist (antiandrogenic) activity, metabolies compete with natural androgen
Interfere - with hormone transport or elimination
- Polychlorinated biphenyl pollutants - (PCBs) Rats exposed to PCBs have low levels of thyroid hormone. Compete for binding sites of thyroid hormone transport protein. Without being bound to this protein, thyroid hormones are excreted from the body (McKinney et al. 1985; Morse et al. 1996)
- Links:
References
- ↑ Griekspoor A, Zwart W, Neefjes J & Michalides R. (2007). Visualizing the action of steroid hormone receptors in living cells. Nucl Recept Signal , 5, e003. PMID: 17464358 DOI.
- ↑ Møller M, Phansuwan-Pujito P & Badiu C. (2014). Neuropeptide Y in the adult and fetal human pineal gland. Biomed Res Int , 2014, 868567. PMID: 24757681 DOI.
- Endocrinology: An Integrated Approach Nussey, S.S. and Whitehead, S.A. London:Taylor & Francis; c2001 Major hormone types
- Genes and Disease, Bethesda (MD): National Library of Medicine (US), NCBI Chapter 41 - Glands and Hormones
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2018 ANAT2341 - Timetable | Course Outline | Moodle | Tutorial 1 | Tutorial 2 | Tutorial 3 |
Labs: 1 Preimplantation and Implantation | 2 Reproductive Technology Revolution | 3 Group Projects | 4 GM manipulation mouse embryos | 5 Early chicken eggs | 6 Female reproductive tract | 7 Skin regeneration | 8 Vertebral development | 9 Organogenesis Lab | 10 Cardiac development | 11 Group projects | 12 Stem Cell Journal Club |
Lectures: 1 Introduction | 2 Fertilization | 3 Week 1/2 | 4 Week 3 | 5 Ectoderm | 6 Placenta | 7 Mesoderm | 8 Endoderm | 9 Research Technology | 10 Cardiovascular | 11 Respiratory | 12 Neural crest | 13 Head | 14 Musculoskeletal | 15 Limb | 16 Renal | 17 Genital | 18 Endocrine | 19 Sensory | 20 Fetal | 21 Integumentary | 22 Birth | 23 Stem cells | 24 Revision |
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