Talk:2009 Lecture 20

Endocrine Development

The human fetus is dependent upon endocrine development for hormones, which support normal development. Peripheral endocrine glands (thyroid, pancreas, adrenals, gonads) form early in the second month from epithelial/mesenchye interactions and differentiate into the third month. The fetus also has a unique hormonal system that combines not only its own developing endocrine system, but also that of the placenta (More? see [placenta.htm Placenta notes]) and maternal hormones.

Abnormal endocrine development/function can impact on many different systems. For example, insufficient maternal dietary iodine impacts on fetal thyroid gland thyroid hormone production, which in turn can lead to abnormal neural development. Alternatively, we now know many environmental and therapeutic chemicals have a wide range of effects on the endocrine system.

Sex hormones from the gonads have significant effects prenatally and postnatally, specifically at puberty with a role to play in male/female biological maturity and have wide actions throughout the body.

Some Recent Findings

Maternal diabetes alters transcriptional programs in the developing embryo. Pavlinkova G, Salbaum JM, Kappen C. BMC Genomics. 2009 Jun 18;10:274. PMID: 19538749 Exposure to maternal diabetes during pregnancy alters transcriptional profiles in the developing embryo. The enrichment, within the set of de-regulated genes, of those encoding transcriptional regulatory molecules provides support for the hypothesis that maternal diabetes affects specific developmental programs.

New discoveries on the biology and detection of human chorionic gonadotropin. Cole LA. Reprod Biol Endocrinol. 2009 Jan 26;7:8. Review. PMID: 19171054

Endocrine activity of extraembryonic membranes extends beyond placental amniotes. Albergotti LC, Hamlin HJ, McCoy MW, Guillette LJ Jr. PLoS One. 2009;4(5):e5452. Epub 2009 May 8. PMID: 19424488 PLOS

Beta cells within single human islets originate from multiple progenitors. Scharfmann R, Xiao X, Heimberg H, Mallet J, Ravassard P. PLoS One. 2008;3(10):e3559. Epub 2008 Oct 29. PMID: 18958289

All beta cells contribute equally to islet growth and maintenance. Brennand K, Huangfu D, Melton D. PLoS Biol. 2007 Jul;5(7):e163. Epub 2007 May 29. PMID: 17535113 PLOS

In healthy adult mice, the beta cell population is not maintained by stem cells but instead by the replication of differentiated beta cells. It is not known, however, whether all beta cells contribute equally to growth and maintenance, as it may be that some cells replicate while others do not. Understanding precisely which cells are responsible for beta cell replication will inform attempts to expand beta cells in vitro, a potential source for cell replacement therapy to treat diabetes. Two experiments were performed to address this issue. First, the level of fluorescence generated by a pulse of histone 2B–green fluorescent protein (H2BGFP) expression was followed over time to determine how this marker is diluted with cell division; a uniform loss of label across the entire beta cell population was observed. Second, clonal analysis of dividing beta cells was completed; all clones were of comparable size. These results support the conclusion that the beta cell pool is homogeneous with respect to replicative capacity and suggest that all beta cells are candidates for in vitro expansion. Given similar observations in the hepatocyte population, we speculate that for tissues lacking an adult stem cell, they are replenished equally by replication of all differentiated cells.

Steroid-hormone rapid actions, membrane receptors and a conformational ensemble model. Norman AW, Mizwicki MT, Norman DP. Nat Rev Drug Discov. 2004 Jan;3(1):27-41. Review. No abstract available. PMID: 14708019

File:Podcasticon.jpg Podcast - 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. Slip this MP3 into your player and listen! [../Podcast/OckhamRazor/CentenaryofHormone.mp3 13 minutes 32seconds 6.2 Mb mp3] | ABC Radio Ockham's Razor | ABC Radio Ockham's Razor Transcript | [../Podcast/podcast.htm About UNSW Embryology Podcasts]

Online Texbooks

External links to online textbooks at NCBI Bookshelf

Developmental Biology (6th ed) by Gilbert Part 3. Later embryonic development, 15. Endoderm

Endocrinology: An Integrated Approach table of Contents

NIH Genes & Disease Chapter 41

Computer Activities

Human Embryology Movies:

Embryo Images Unit:

Requires Internet connection

Pituitary Gland

Development Overview

http://www.ncbi.nlm.nih.gov/pubmed/19812240 http://cercor.oxfordjournals.org/cgi/content/full/bhp212v1
- Hypothyroxinemia affects 35-50% of neonates born prematurely (12% of births) and increases their risk of suffering neurodevelopmental alterations. In conclusion, maternal THs are still essential for normal offspring's neurodevelopment even after onset of fetal thyroid function.

Parathyroid

Thymus

Pancreas

Pancreas Development Notes

Adrenal (Suprarenal)

Adrenal Development Notes

Gonads

(Covered in Sexual Differentiation) - Endocrine Gonad Notes | Genital Development

Placenta

Endocrine Placenta Notes | Placenta Development

Maternal

http://www.ncbi.nlm.nih.gov/pubmed/19812240 http://cercor.oxfordjournals.org/cgi/content/full/bhp212v1

Maternal hormones - can cross the placental barrier, contribute precursors to placental hormone production.

Other Cells

[endocrine18.htm Endocrine Other Cells Notes]

Selected cells within the following organs also contribute to endocrine regulation.

Digestive Tract -
Heart -
Kidney -

Internal LinksEndocrine

Introduction[endocrine2.htm Abnormalities][endocrine3.htm Stage 13/14][endocrine4.htm Stage 22][endocrine5.htm Selected Stage 22][endocrine8.htm Thyroid][endocrine7.htm Pituitary][endocrine9.htm Adrenal][endocrine10.htm Pancreas][endocrine12.htm Pineal][endocrine13.htm Thymus][endocrine15.htm Gonad][endocrine14.htm Placenta][endocrine16.htm Hypothalmus][endocrine17.htm Parathyroid][endocrine18.htm Adipose Tissue][endocrine19.htm Other Tissues][endocrine11.htm Molecular][endocrinelink.htm Web Links]

Classification by structure of the major human hormones

Hormone	Peptide/protein	Steroid	Amino acid or fatty acid derived
Hypothalamic hormones	Thyrotrophin releasing hormone (TRH)
	Corticotrophin releasing hormone (CRH)
	Arginine vasopressin (AVP)
	Gonadotrophin releasing hormone (GnRH)
	Growth hormone releasing hormone (GHRH)
	Somatostatin
	Prolactin relasing factor (PRF)
	Dopamine
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
Thyroid hormones			Thyroxine (T4)
			Triiodothyronine (T3)
Pancreatic hormones	Insulin
	Glucagon
	Somatostatin
	Pancreatic polypeptide
Calcium regulating hormones	Parathyroid hormone (PTH)	1,25-dihydroxyvitamin D
	Calcitonin (CT)
	Parathyroid hormone-related peptide (PTHrp)
Adrenal cortical steroids		Cortisol
		Aldosterone
		Dehydroepiandrosterone
Adrenal medullary hormones			Epinephrine
			Norepinephrine
Male reproductive hormones	Inhibin	Testosterone
		Dihydrotestosterone
Female reproductive hormones	Inhibin	Estradiol
	Oxytocin	Progesterone
	Human chorionic gonadotropin (hCG)
	Human chorionic somatotrophin
Plasma volume and sodium regulating hormones	Atrial natriuretic peptide (ANP)
	Arginine vasopressin
	Renin/angiotensin	Aldosterone
Cardiovascular hormones	Atrial natriuretic peptide (ANP)		Nitric oxide
	Endothelins
	Erythropoietin
	Bradykinin
Pineal hormones			Melatonin
			Serotonin
Growth factors or cytokines	Insulin-like growth factors (IGFs)
	Epidermal growth factor (EGF)
	Interleukins (ILs)
	Tumor necrosis factor (TNF)-alpha
Eicosanoids			Prostaglandins
			Thromboxanes
			Prostacyclin
			Leucotrienes
			Lipoxins

Comments

This section of notes covers the endocrine system organs, development and function.

This first page introduces the system and gives a general [#Overview Development Overview]. Subsequent linked pages focus on specific organs.

Each organ in the endocrine system has an important role to play during embryonic development and postnatally.