Medical Illustrations of the Development of the Human Embryo

Here we have medical illustrations showing the development of the human embryo week by week. This is the start of life termed the embryonic period and covers the fertilised cell up to eight weeks of development. It is followed by the fetal period which starts from the 8th week of development through to birth.

The embryonic period is characterized by the growth and maturation of tissues and organs from a single fertilised cell. Heart sounds for example can be detected as early as 8 or 9 weeks. Although the embryo only reaches the size of a kidney bean at 8 weeks measuring 1.6cm, the organs and muscles and nerves have already begun to function.

Developments through the embryonic period are included in the series of medical illustrations as below, to provide a week by week visual story.

For illustrations of the continued growth of the embryo onto the fetal stages, please click here.

Fertilisation

Fertilisation occurs when a males sperm fertilises a woman's egg or ovum, taking place inside one of the fallopian tubes. Fertilisation is completed when the nuclei of the egg and sperm have combined, creating a single cell that is then capable of further development by dividing into further cells. The journey of the fertilised egg carries along the fallopian tube for about four days, where by the single cells has been dividing untill it is a ball of cells surrounding a fuid filled hollow called a Blastocyst. Upon reaching the uterus or womb, this Blastocyst is ready to attach itself to the uterus wall, which has already formed a spongy lining. The embyro burries itself into the wall of the uterus untill it is fully covered. It is here the embryo will develop, forming a placenta to gain nutrients to grow.

Ovulation Illustration

Ovulation where one or more eggs are released from the ovary

Male reproduction

Release of an oocyte, the immature female reprodcutive cell

Female midsagittal cross section

Sperm fertilising the egg

 

The fertilised cell at week 1

The fertilised cell at week 1

Cell development at week 2

Cell development at week 2

Embryo development at week 3

Embryo development at week 3

 
Embryo development at week 4s

Embryo development at week 4

Embryo development at week 5

Embryo development at week 5

Embryo development at week 6

Embryo development at week 6

 
Embryo development at week 7

Embryo development at week 7

Embryo development at week 8

Embryo development at week 8

Week 4 in close detail

Week 4 in close detail

 
Week 5 in close detail

Week 5 in close detail

Week 6 in close detail

Week 6 in close detail

Week 7 in close detail

Week 7 in close detail

 
Foetus development at 8 weeksr

Foetus development at 8 weeks

Vertical transverse classical incisions

Foetus development at 8 weeks

 

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