BGDA Practical - Implantation to 8 Weeks

From Embryology


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

Human development timeline
Stage11 sem6.jpg
  Practical 3 - Fertilization to Implantation   Practical 6 - Implantation to 8 Weeks   Practical 12 - Fetal Period
Practical 14 - Placenta and Fetal Membranes

The first Embryology practical covered gametogenesis, fertilization, implantation and early events of embryonic development. The third week is the begining of the embryonic period which continues through to week eight. This period of development is complex, and an entire class could be spent on folding or development of any one organ system. Therefore the Lab must be reasonably general when covering organogenesis, organ/system development. In particular, the following topics are covered in detail in BGD Cycle B: gastrointestinal tract, head, sensory and urogenital development. These topics will not be described in detail here.

We will also be using the Carnegie stage 7-23 images to examine external changes on the embryo. These stages are also shown in the movie "Carnegie stage human growth through embryonic period". Identify the key structures in figures on the following pages and discuss as a small group the dynamic events of development that are occurring at this early stage. If required ask your tutor for assistance. For new terms use the glossary link found at the bottom of each page.

<html5media height="496" width="386">File:Embryo stages 003.mp4</html5media>

Click Here to play on mobile device

Stages are based on the external and/or internal morphological development of the vertebrate embryo, and are not directly dependent on either age or size. The human embryonic period proper is divided into 23 Carnegie stages. Criteria beyond morphological features include age in days, number of somites present, and embryonic length. Important note - the day timing of stages is only approximate, it is the sequence that is important.

Staging can be applied to all vertebrates, and most vertebrate embryos develop during the embryonic period in much the same way, we can directly compare the timing of development for different species.

Practical Class Note

  • Material under the heading "Additional Information" on each page is not part of today's practical and is provided as supporting information only.
  • "Embryo Stages and Events" is part of this additional information and is provided to allow you to see what else is going on within the embryo.
1 Minute Embryology | UNSW theBox


Embryo logo Hill, M.A. (2020). UNSW Embryology (20th ed.) Retrieved May 18, 2024, from
The Developing Human, 10th edn.jpg Moore, K.L., Persaud, T.V.N. & Torchia, M.G. (2015). The developing human: clinically oriented embryology (10th ed.). Philadelphia: Saunders.(links only function with UNSW connection)

Chapter 5 Fourth to Eighth Weeks of Human Development

Chapter 6 Fetal Period

Chapter 20 Human Birth Defects

Larsen's human embryology 5th ed.jpg Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R., Francis-West, P.H. & Philippa H. (2015). Larsen's human embryology (5th ed.). New York; Edinburgh: Churchill Livingstone.(links only function with UNSW connection)

Chapter 3 Third Week: Becoming Trilaminar and Establishing Body

Chapter 4 Fourth Week: Forming the Embryo

Chapter 6 Fetal Development and the Fetus as Patient

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


BGDA: Lecture 1 | Lecture 2 | Practical 3 | Practical 6 | Practical 12 | Lecture Neural | Practical 14 | Histology Support - Female | Male | Tutorial

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

Cite this page: Hill, M.A. (2024, May 18) Embryology BGDA Practical - Implantation to 8 Weeks. Retrieved from

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