One Minute Embryology
|Embryology - 1 Dec 2021 Expand to Translate|
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These are a set of quick introductory videos with audio commentary designed to get students to begin to think about specific embryology topics. Videos have also been posted on UNSW theBox and YouTube Embryology channel. This page is still under development in 2016.
These videos run for about 1 minute and are not intended as a detailed description or for use elsewhere.
The first videos relate to undergraduate Medicine phase 1 embryology in BGDA and BGDB.
Here is a quick description of the early events in the human development timeline.
- Links: original movie page | UNSW theBox | YouTube | BGDA lecture | BGDA Prac 3 | BGDA Prac 6 | Embryonic Development | Fetal Development
Lets look at an overview of human development
Human pregnancy occurs over 9 months.
This is traditionally divided into 3 trimesters each 3 months long.
The first trimester is mainly the embryonic period.
While the second and third trimester is the fetal period of growth.
The embryonic period is divided into 23 “stages” over the first 8 weeks.
After the last menstrual cycle, this period also covers the next 2 and a half missed cycles.
Human pregnancy is measured from this last cycle, while fertilisation occurs around ovulation of the next missed cycle.
A positive pregnancy test can be seen 2 weeks later after fertilisation.
The fertilised oocyte is called a zygote, that divides to form a morula.
Further mitotic division forms a blastocyst.
Forming a bilaminar then trilaminar embryo in week 3.
Looking at events
end of week 1 - blastocyst hatching
week 2 - Implantation in the uterus
week 3 - Key developmental processes
week 4 - the heart and other structures form
Here is a quick description of the external embryonic events in human development between week 3 and 8.
- Links: UNSW theBox | YouTube | BGDA lecture | BGDA Prac 6 | Embryonic Development | Fetal Development
Here is a brief description of embryonic development between week 3 to 8
In Week 3 the embryonic disc forms
Amniotic sac removal shows the epiblast layer
Gastrulation occurs at the primitive node and streak
Axial process and axes are established
The disc folds ventrally
The embryo is now 2 mm long
Watch embryo growth from week 4 onward
In week 4, somites, neural plate folding and formation of the heart
In week 5, sensory placodes, pharyngeal arches and limb buds develop
In week 6, external ear primordia and the limb plates appear
In week 7, upper lip and maxilla fuse and limb digital rays appear
In week 8, limbs grow and have mature form
The external ear fuses and eyelids can be seen
There is also overall growth in size
That has been a quick external view of human embryonic development
Here is a quick description of the endoderm events during week 3 and 4 in developing the gastrointestinal tract.
- Links: original movie page | UNSW theBox | BGDB lecture | BGDB practical | Gastrointestinal Tract Development
Human Face and Palate
Here is a quick description of the embryonic events in the human face and palate development between week 5 and 9.
Lets look at head and palate development between week 5 to 9.
This is a ventrolateral view of the human head in week 5.
The primitive oral cavity is located on the ventral surface.
Beneath it (oral cavity) are the large mandibular processes of the first arch.
Beside it (oral cavity) are the small maxillary processes of the first arch.
Above it (oral cavity) are the nasal parts of the large frontonasal process.
The maxillary and FNP together form the upper lip and palate.
The second view is in week 7 showing the oral cavity roof.
The palatal shelves extend from the 2 maxillary processes.
The animation runs forward to week 9 when they fuse together.
Lets watch this again looking at the fusion of the palatal shelves with the midline nasal septum.
The third view shows the anterior view of the shelves and septum fusing in week 9.
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.
Cite this page: Hill, M.A. (2021, December 1) Embryology One Minute Embryology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/One_Minute_Embryology
- © Dr Mark Hill 2021, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G