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==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 ==
[[File:Thyroid_pyramidal_lobe.jpg|thumb|Thyroid pyramidal lobe]]
[[File:Thyroid uptake scans .jpg|thumb|Thyroid uptake scans]]
* 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. [http://www.upstate.edu/cdb/grossanat/imgs/tgdfig2.jpg 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.
* 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)
==References==
<references/>
* NIH Genes & Disease [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gnd.chapter.41 Chapter 41 - Glands and Hormones]
* 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]
===Search ===
* '''Bookshelf'''  [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=endocrine endocrine] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=pineal_gland pineal gland] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=hypothalmus hypothalamus] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=pituitary_gland pituitary gland] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=thyroid_gland thyroid gland] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=parathyroid_gland parathyroid gland] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=thymus_gland thymus gland] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=endocrine_pancreas endocrine pancreas]  | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=adrenal_gland adrenal gland]
* '''Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/gquery?itool=toolbar&cmd=search&term=endocrine_development endocrine development]
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[[Category:Abnormalities]] [[Category:Endocrine]]

Revision as of 23:41, 5 October 2010

Introduction

Human adrenal gland (Week 10)

The endocrine system has an ongoing important role in embryonic, fetal and postnatal development as well as maintainance of homeostasis and reproductive function. There exists a complex interaction between the maternal and fetal endocrine system during development and failure for fetal endocrine development has a cascading effect on many other developing systems. There are additional pages covering abnormalities of specific endocrine organs.

In addition to many genetic effects, we now know that there are many potential environmental factors which can impact upon development.

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 are recognised by either cell surface receptors (modified amino acids, peptides, proteins) or cytoplasmic/nuclear receptors (steroids). Hormones “orchestrate” responses in other tissues, including other endocrine organs, and these overall effects can be similar or different in different tissues. In addition, 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.

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 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.

Endocrine Links: Introduction | BGD Lecture | Science Lecture | Lecture Movie | pineal | hypothalamus‎ | pituitary | thyroid | parathyroid | thymus | pancreas | adrenal | endocrine gonad‎ | endocrine placenta | other tissues | Stage 22 | endocrine abnormalities | Hormones | Category:Endocrine
Historic Embryology - Endocrine  
1903 Islets of Langerhans | 1903 Pig Adrenal | 1904 interstitial Cells | 1908 Pancreas Different Species | 1908 Pituitary | 1908 Pituitary histology | 1911 Rathke's pouch | 1912 Suprarenal Bodies | 1914 Suprarenal Organs | 1915 Pharynx | 1916 Thyroid | 1918 Rabbit Hypophysis | 1920 Adrenal | 1935 Mammalian Hypophysis | 1926 Human Hypophysis | 1927 Adrenal | 1927 Hypophyseal fossa | 1930 Adrenal | 1932 Pineal Gland and Cysts | 1935 Hypophysis | 1935 Pineal | 1937 Pineal | 1935 Parathyroid | 1940 Adrenal | 1941 Thyroid | 1950 Thyroid Parathyroid Thymus | 1957 Adrenal

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

Thyroid pyramidal lobe
Thyroid uptake scans
  • 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.
  • 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)

References

Search

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Cite this page: Hill, M.A. (2024, March 29) Embryology Endocrine System - Abnormalities. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Endocrine_System_-_Abnormalities

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G