File:1 Min Embryo - Human timeline.mp4

One Minute Embryology - Human Timeline

One Minute Embryology

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Audio Script

Hi there,

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

Cite this page: Hill, M.A. (2024, April 27) Embryology 1 Min Embryo - Human timeline.mp4. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:1_Min_Embryo_-_Human_timeline.mp4

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