2010 BGD Practical 6 - Week 5

From Embryology

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 fifth week (week 5) following fertilization or Clinical week 7 (LMP).

By this week there are many different organs and tissues differentiating throughout the embryo, only a few select systems will be discussed.

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 3 | download (2.1 Mb MP3 16:14)

Cardiovascular

Respiratory

  • left and right lung buds push into the pericardioperitoneal canals (primordia of pleural cavity)

Neural

  • Central nervous system - secondary brain vesicles
  • Sensory - Hearing cochlear part of otic vesicle elongates (humans 2.5 turns)

Cardiovascular

Basic Heart Development Timeline.jpg

Heart Development Timeline (see Basic Cardiac Embryology)

Stage13-CVS-icon.jpg

Respiratory

Respiratory Tract (stage 13)
Stage13-GIT-icon.jpg Week 4 - laryngotracheal groove forms on floor foregut.

Week 5 - left and right lung buds push into the pericardioperitoneal canals (primordia of pleural cavity)

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

Week 7 - enlargement of liver stops descent of heart and lungs.

Month 3-6 - lungs appear glandular, end month 6 alveolar cells type 2 appear and begin to secrete surfactant.

Month 7 - respiratory bronchioles proliferate and end in alveolar ducts and alveolar sacs.

Neural

Neural tube - brain flexures (stage 13)
Neural - 5 secondary vesicles
Stage13-CNS-icon.jpg Rapid growth folds the neural tube forming 3 brain flexures:
  1. cranial flexure (cephalic)- pushes mesencephalon upwards
  2. pontine flexure - generates 4th ventricle
  3. cervical flexure - between brain stem and spinal cord

Movies

Cardiovascular

Heart1 looping icon.jpg Heart1 realign icon.jpg Heart1 atrium icon.jpg Heart1 ventricle icon.jpg
Heart Looping Heart Realign Heart Atrial Septation Heart Outflow Septation

See also Heart Development Timeline - Basic Cardiac Embryology

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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

Embryo Stages and Events

Day Stage Event
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Pituitary Week 5 elongation, contacts infundibulum, diverticulum of diencephalon

Heart Week 5 septation starts, atrial and ventricular

Respire Week 5 left and right lung buds push into the pericardioperitoneal canals (primordia of pleural cavity)

Respire Week 5 to 17 lung histology - pseudoglandular

Sense - Hearing Week 5 cochlear part of otic vesicle elongates (humans 2.5 turns)

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31
   
32
Stage 14 Stage14 bf1c.jpg Ectoderm - sensory placodes, lens pit, otocyst, nasal placode, primary/secondary vesicles, fourth ventricle of brain

Mesoderm - continued segmentation of paraxial mesoderm (somite pairs), heart prominence

Head - 1st, 2nd and 3rd pharyngeal arch, forebrain, site of lens placode, site of otic placode, stomodeum

Body - heart, liver, umbilical cord, mesonephric ridge visible externally as bulges.

Limb - upper and lower limb buds growing

Neural first appearance of the future cerebral hemispheres. Cerebellar plate differentiated to an intermediate layer, and future rhombic lip identifiable PMID: 3377191

GIT - Liver hepatic gland and its vascular channels enlarge, hematopoietic function appears PMID: 9407542

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Stage 15 Stage15 bf1c.jpg

Neural cranial nerves (except olfactory and optic) are identifiable in more advanced embryos PMID: 3213956

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35
  Sense - Eye 35 to 37 days retinal pigment present

Glossary Links

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

Cite this page: Hill, M.A. (2019, October 21) Embryology 2010 BGD Practical 6 - Week 5. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2010_BGD_Practical_6_-_Week_5

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