Difference between revisions of "2010 BGD Practical 6 - Week 6"

From Embryology
(Endocrine Development)
(Endocrine Development)
 
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==Endocrine Development==
 
==Endocrine Development==
These organs mainly develop in the embryonic period and function in the fetal period.
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These organs mainly develop in the embryonic period and function in the fetal period. (Covered in next practical)
  
* Thyroid - thyroid median endodermal thickening in the floor of pharynx outpouch – thyroid diverticulum (day 24) (Covered in next practical)
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* '''Thyroid''' - develops from thyroid median endodermal thickening in the floor of pharynx outpouch – [[T#thyroid diverticulum|thyroid diverticulum]] (day 24), functions from week 10
* Pituitary - develops from surface (anterior) and neural tube (posterior) ectoderm, connecting stalk between pouch and oral cavity degenerates
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* '''Pituitary''' - develops from surface (anterior) and neural tube (posterior) ectoderm, connecting stalk between pouch and oral cavity degenerates
* Parathyroid  - diverticulum elongate, hollow then solid, dorsal cell proliferation
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* '''Parathyroid''' - develop from endoderm of [[P#pharyngeal pouch|pharyngeal pouches]], diverticulum elongate, hollow then solid, dorsal cell proliferation
* Thymus  - diverticulum elongate, hollow then solid, ventral cell proliferation
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* '''Thymus''' - develops from 2 origins for lymphoid thymocytes and thymic epithelial cells, diverticulum elongate, hollow then solid, ventral cell proliferation
* Adrenal - fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia
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* '''Adrenal''' - develops from 2 origins [[A#adrenal medulla|adrenal medulla]] (neural crest) and fetal cortex (surrounding mesenchyme), fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia
* Gonad - germ cells migrate into gonadal ridge
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* '''Gonad''' - develops from 2 origins, germ cells migrate into the [[G#genital ridge|genital ridge]] (mesothelium and underlying mesenchyme)
  
 
===Sex Determination===
 
===Sex Determination===
* Humans (week 5-6)
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* Humans (week 5-6), germ cells do not determine sex, it is the support cells
 
* [[G#germ cell|germ cells]] migrate into [[G#gonadal ridge|gonadal ridge]]
 
* [[G#germ cell|germ cells]] migrate into [[G#gonadal ridge|gonadal ridge]]
 
* [[G#gonad|Gonads]] (male - testis, female - ovary) identical at this stage, termed "indifferent"
 
* [[G#gonad|Gonads]] (male - testis, female - ovary) identical at this stage, termed "indifferent"
 +
  
  

Latest revision as of 17:16, 23 May 2010

Introduction

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Practical 6: Week 3 | Week 4 | Week 5 | Week 6 | Week 7 | Week 8 | Quiz


Key Events of Human Development during the sixth week (week 6) following fertilization or Clinical week 8 (LMP).

Practical Audio

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BGD Cycle A 2010 Audio - Dr Mark Hill Monday 17th May 2010 3-5pm G2G4.

Note - this is a live unedited recording from the practical and may contain errors in either descriptions or content.

listen Part 4 | download (1.9 Mb MP3 14:08)

--Mark Hill 08:30, 18 May 2010 (EST) Note this page has been updated to add thyroid and gonad information.

Endocrine Development

These organs mainly develop in the embryonic period and function in the fetal period. (Covered in next practical)

  • Thyroid - develops from thyroid median endodermal thickening in the floor of pharynx outpouch – thyroid diverticulum (day 24), functions from week 10
  • Pituitary - develops from surface (anterior) and neural tube (posterior) ectoderm, connecting stalk between pouch and oral cavity degenerates
  • Parathyroid - develop from endoderm of pharyngeal pouches, diverticulum elongate, hollow then solid, dorsal cell proliferation
  • Thymus - develops from 2 origins for lymphoid thymocytes and thymic epithelial cells, diverticulum elongate, hollow then solid, ventral cell proliferation
  • Adrenal - develops from 2 origins adrenal medulla (neural crest) and fetal cortex (surrounding mesenchyme), fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia
  • Gonad - develops from 2 origins, germ cells migrate into the genital ridge (mesothelium and underlying mesenchyme)

Sex Determination

  • Humans (week 5-6), germ cells do not determine sex, it is the support cells
  • germ cells migrate into gonadal ridge
  • Gonads (male - testis, female - ovary) identical at this stage, termed "indifferent"


BGDsmall.jpg

Practical 6: Week 3 | Week 4 | Week 5 | Week 6 | Week 7 | Week 8 | Quiz


   

Additional Information

Additional Information - Content shown under this heading is not part of the material covered in this class. It is provided for those students who would like to know about some concepts or current research in topics related to the current class page.


Detailed Week by Week

The following information is a detailed timeline of embryonic development between week 3 to 8 and content does not form part of the current practical class.

Week 3 | Week 4 | Week 5 | Week 6 | Week 7 | Week 8

Endocrine Development

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 | 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 Hypophyseal fossa | 1932 Pineal Gland and Cysts | 1935 Hypophysis | 1937 Pineal | 1938 Parathyroid | 1940 Adrenal | 1941 Thyroid | 1950 Thyroid Parathyroid Thymus | 1957 Adrenal

| original page

Embryo Stages and Events

Day Stage Event
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Pituitary Week 6 - connecting stalk between pouch and oral cavity degenerates

Parathyroid Week 6 - diverticulum elongate, hollow then solid, dorsal cell proliferation

Thymus Week 6 - diverticulum elongate, hollow then solid, ventral cell proliferation

Adrenal Week 6 - fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia

Respire Week 6 - descent of heart and lungs into thorax. Pleuroperitoneal foramen closes

Tongue Week 6 - gustatory papilla, caudal midline near the foramen caecum (week 6 to 7 - nerve fibers approach the lingual epithelium)

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Stage 16 Stage16 bf1c.jpg Neural first parasympathetic ganglia, submandibular and ciliary, are identifiable PMID: 2751117

Limbs upper limb bud nerves median nerve, radial nerve and ulnar nerve entered into hand plate, myoblasts spindle shaped and oriented parallel to limb bud axis.

Heart outflow tract elliptical configuration with four cushions, the two larger fusing at this stage. Semilunar valve leaflets form at the downstream end of the cushions

Head lip and palate components of the upper lip, medial nasal prominence and maxillary process present, median palatine process appears.

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Stage 17 Stage17 bf1c.jpg

Neural telencephalon areas of the future archicortex, paleocortex, and neocortex, visible. Beginning of future choroid plexus PMID: 2802187

Sense - Smell olfactory nerve fibres enter the brain PMID: 15604533

Neural primordium of the epidural space appears first on the ventral part of the vertebral canal and develops rostro-caudally PMID: 15478101

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  Heart separation of common cardiac outflow (aortic arch and pulmonary aorta)


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
2010 BGD: Lecture 1 | Lecture 2 | Practical 3 | Practical 6 | Practical 12

Cite this page: Hill, M.A. (2019, December 7) Embryology 2010 BGD Practical 6 - Week 6. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2010_BGD_Practical_6_-_Week_6

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G