UNSW Embryology

Beginnings, Growth and Development

© Dr Mark Hill (2010)

Acknowledgements

Practical: Embryology of the Gastro-Intestinal Tract

Aim:This practical is an introduction to development of the Gastro-Intestinal Tract (GIT).

Key Concepts: endoderm, foregut, midgut, hindgut, buccopharyngeal membrane, cloacal membrane, mesenteries, peritoneal space, midgut herniation, folding, liver, pancreas, spleen

Key Reading:

• BGD-B 2009 Laboratory Notes: Practical 1: Embryology of the Gastrointestinal Tract (PDF 4 pages, 260 kB)
• Human Embryology, WJ. Larsen Chapter 9 p229-260
• The Developing Human: Clinically Oriented Embryology (6th ed.) Moore & Persaud Chapter 12 p271-302

Page Links: What should I do in the Practical? | Where should I start with Embryology? | Where should I start with GIT? | Where are the GIT Lecture slides? |Next | Glossary of Terms |

What should I do in the Practical?

Don't Panic! This is a complex topic, that begins very early in embryonic development, continues through fetal and into postnatal times, so we will not be covering everything in the class.

The Practical is a series of only 6 linked webpages that take you through an overview of the process of gastrointestinal tract (GIT) development:

1. Trilaminar Embryo
2. Folding
3. Early Embryo
4. Late Embryo
5. Fetal
6. Postnatal

We will spend more time on the early parts of GIT development (embryonic stage), the latter pages will need some self-directed learning.

I have also included additional webpages and resources for you to look at in your own time:

• Background
• Associated Organs
• Histology
• Abnormalities

Where should I start with Embryology?

Many of you will never have studied Embryology before, so many of the concepts, terms and timing of development will be new to you. Unfortunately we do not have time in this Practical to cover these many issues, here's a chance for self-directed learning!

1. In humans, we generally divide development into the Early (week 1 to 8) Embryonic period and Late (week 9 to 36) Fetal period.
2. Look at Embryo stages and timeline of human development to understand the timecourse of development.
3. Alternatively, look at class notes BGD Cycle A Practical 4 and 11.
4. Use the Glossary link found at the bottom of each page to help with these new terms.
5. For GIT development read the suggestion "Where should I start with GIT?" below.
6. Look at an alternate presentation of similar data under System - GIT notes section.

   Gastrointestinal Notes ----------------- Introduction Overview Stage 13/14 Stage 13/14 3D Model Stage 22 Stage 22 3D Model Stage 22 Selected Highpower Stomach Intestine GIT Folding Liver Gall Bladder Spleen Pancreas Enteric Nervous System Tongue Taste Postnatal Milk Molecular Movies Abnormalities Ultrasound Gastroschisis References

7. I also give this GIT lecture in Science Embryology and here are a set of earlier 2004 ANAT2310 GIT slides.

GIT Lecture Slides

Lecture slides and additional resources are available on GIT Lecture page. Lecture slides should also eventually appear on WebCT.

Where should I start with GIT?

Here's one suggestion.

• Firstly, in normal development many organs/tissues have origins and intermediate structures, forms, or relationships which occur at specific times. So try and relate the appearance of the GIT to specific times in development.
• Next, in normal development there are many physical processes occurring: differentiation, migration, folding, cavitation, growth, elongation, proliferation, cell death, etc. Only some of these are processes will be visible in the images we will be looking at. Use the movies and animations to help your understanding of dynamic processes.
• Next, anatomical tissues and organs are in general formed from a number of different embryonic origins. Abnormalities in any one of these original tissues or processes can have subsequent effects on the development or function of specific organs.
• Remember that the prenatal GIT is digestively functionally inactive (nutrition is through the placenta) compared to the postnatal GIT (though other specific functions can be occurring prenatally).
• Finally, even with the best diet postnatal growth and health is dependent upon a properly functioning GIT system.

Here's another suggestion. As you follow the timecourse of GIT development think about:

• What contributes
• What develops
• What functions
• What changes

Now follow the white rabbit....

Next

Link to next page in this GIT Practical - Trilaminar Embryo This page starts the Practical by taking you through the first 3 weeks of development.

Glossary

Use the alphabetical list below to find definitions of terms that are new to you or use the Google search window to search UNSW Embryology site.

Terms

On each page of this practical will be a list of terms relevant to the page contents.

Quick Links

Everything Medicine 2009 ----------------- Found - Intro Embryo Lecture Found - Intro Embryo Practical Found Expert Tutorial-Histology SH - Respiratory Lecture ----------------- BGD - GIT Lecture BGD - GIT Practical Prac1 GIT Manual PDF GIT Development GIT Abnormalities ----------------- BGD - Head Lecture BGD - Head Practical Prac6 Head Manual PDF Head and Neck Development Face Development Ear Development Face Abnormalities ----------------- BGD - Endocrine Lecture Endocrine Development Endocrine Abnormalities ----------------- BDG - Male/Female Lecture BGD - Male/Female Practical Prac12 Male/Female Manual PDF Genital Development Male Development Female Development Genital Abnormalities ----------------- BGD-B Full Prac Manual PDF BGD-B FAQs BGD Phase 2 - Tutorial CBL ILPs 2009 eMed ----------------- Week by Week Movies Audio Development Notes System Notes

UNSW Embryology ISBN: 978 0 7334 2609 4

UNSW CRICOS Provider Code No. 00098G