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Charlotte Lozier Institute

Phone: 202-223-8073
Fax: 571-312-0544

2776 S. Arlington Mill Dr.
#803
Arlington, VA 22206

The
Voyage of Life
Weeks 1 and 2
Week 3
Week 4
Week 5
Week 6
Week 7
Week 8
Week 9
Week 10
Week 11
Week 12
Week 13
Week 14
Weeks 15 & 16
Weeks 17 & 18
Weeks 19 & 20
Weeks 21 & 22
Month 6
Month 7
Month 8
Month 9 and Birth

Week 10

Fingers, toes, and a working digestive system

Human Prenatal Age
  • Post-conception week 8
  • Days 49-55
  • Gestational Week 10
Highlights

  • Toes and fingers are free to wiggle.

  • The embryo shows a preference for the right or left hand.1

  • The electrical activity recorded from the heart of an unborn child resembles that of a newborn.2

  • The brain is still extremely large and makes up ~43% of the embryo’s total weight.3 For comparison, the brain is only 10% of the newborn’s body weight and 2% of an adult’s body weight.

Week ten marks the end of the embryonic period.  The embryo has grown from a single cell into nearly one billion cells that form over 4,000 distinct anatomic structures.4 The adult has about 4,500 named body parts, so this means that over 90% of these structures first appear during the embryonic period.5

This image shows an embryo alive in the womb recorded using fetoscopy at 8 weeks following fertilization (or 10 weeks gestation). Note how the fingers are separate and the toes are free to wiggle. (Image credit: The Center for Bioethical Reform)

The embryo can now bend his elbows and bring his hands together. The embryo can also roll over within the amniotic sac, squint, grasp and point his toes.6 When the embryo touches his face, he will frequently move his head away.7 The embryo even makes intermittent breathing motions.8

The front and back of the eyeball fuse together. At this point, the eye has a lens, cornea, and retina.9 The retina will continue growing and maturing for the rest of the pregnancy, and visual acuity continues improving for the first four years of childhood.10

In week 10, the digestive system and kidneys start working. The stomach and pancreas start making most of the digestive enzymes.11 Interestingly, there is not enough space in the fetal abdomen for the entire intestine, so a few of the loops of intestine remain just under the umbilical cord until 12 weeks.12  The kidneys start to filter toxins out of the blood stream. The embryo starts to produce urine and pee into the amniotic fluid.13  After an adult swallows food, contractions in his esophagus and intestines help propel the food forward in a process called peristalsis. Peristalsis begins in the embryo’s large intestine in the week 10 and continues for the rest of his life.14

This week, males develop testes. The testes start producing testosterone, and another hormone called anti- Mullerian hormone. These hormones help develop the rest of the male genitalia. Without these two hormones, the embryo would develop female genitalia, even if the embryo had a Y-chromosome and was genetically male.15

Up until this point, the embryo’s internal organs were easily viewed through the thin skin. Around ten weeks, the skin develops a second layer of cells, hiding the internal organs but leaving most blood vessels visible.16

Note how the skin is opaque on these fingers and toes. Just a few days ago, it was easy to see the developing tissues underneath. (Image Credit: Priests for Life)
The eye continues developing rapidly. This video comes from an embryo 7 ½ weeks after conception, or 9 ½ weeks gestation, because gestational age is usually 2 weeks older than embryonic age.
Dive Deeper
Right and Left-Handedness
At 10 weeks, it is possible to determine left-handedness or right-handedness...
Read More
Eye Formation
The eyes begin forming 22 days after conception...
Read More
Back to The Voyage of Life
Sources
  1. Peter G Hepper, Glenda R Mccartney, and E. Alyson Shannon, “Lateralised Behaviour in First Trimester Human Foetuses,” Neuropsychologia 36, no. 6 (June 1, 1998): 531–34, https://doi.org/10.1016/S0028-3932(97)00156-5.
  2. E Gardner and R O’Rahilly, “The Nerve Supply and Conducting System of the Human Heart at the End of the Embryonic Period Proper.,” Journal of Anatomy 121, no. Pt 3 (July 1976): 571–87.
  3. H. V. Jordaan, “Development of the Central Nervous System in Prenatal Life.,” Obstetrics and Gynecology 53, no. 2 (February 1979): 146–50.
  4. O’Rahilly, R, and F Mueller. Human Embryology and Teratology. 3rd ed. Wiley-Liss, 2001.
  5. O’Rahilly, R, and F Mueller. Human Embryology and Teratology. 3rd ed. Wiley-Liss, 2001.
  6. de Vries, J. I. P. de, G. H. A. Visser, and H. F. R. Prechtl. 'The Emergence of Fetal Behaviour. I. Qualitative Aspects.' Early Human Development 7, no. 4 (December 30, 1982): 301–22. https://doi.org/10.1016/0378-3782(82)90033-0.
  7. de Vries, J. I. P. de, G. H. A. Visser, and H. F. R. Prechtl. 'The Emergence of Fetal Behaviour. I. Qualitative Aspects.' Early Human Development 7, no. 4 (December 30, 1982): 301–22. https://doi.org/10.1016/0378-3782(82)90033-0.
  8. de Vries, J. I. P. de, G. H. A. Visser, and H. F. R. Prechtl. 'The Emergence of Fetal Behaviour. I. Qualitative Aspects.' Early Human Development 7, no. 4 (December 30, 1982): 301–22. https://doi.org/10.1016/0378-3782(82)90033-0.
  9. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  10. Pan, Ying, Kristina Tarczy-Hornoch, Susan A. Cotter, Ge Wen, Mark S. Borchert, Stanley P. Azen, Rohit Varma, and Multi-Ethnic Pediatric Eye Disease Study (MEPEDS) Group. 'Visual acuity norms in pre-school children: the Multi-Ethnic Pediatric Eye Disease Study.' Optometry and Vision Science 86, no. 6 (2009): 607-612. DOI: 10.1097/OPX.0b013e3181a76e55.
  11. Robert K. Montgomery, Andrew E. Mulberg, and Richard J. Grand, “Development of the Human Gastrointestinal Tract: Twenty Years of Progress,” Gastroenterology 116, no. 3 (March 1, 1999): 702–31, https://doi.org/10.1016/S0016-5085(99)70193-9.
  12. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  13. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  14. Richard J. Grand, John B. Watkins, and Frank M. Torti, “Development of the Human Gastrointestinal Tract: A Review,” Gastroenterology 70, no. 5 (May 1, 1976): 790–810, https://doi.org/10.1016/S0016-5085(76)80277-6.
  15. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  16. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
See Full Bibliography

All images and illustrations on The Voyage of Life were reviewed by credentialed scientists for accuracy.

Medical art animation was used to provide a schematic representation of fetal development, with some features, including timing, not to scale. The animation was chosen as an ethically uncompromised guide to fetal development. There are many real human images at each developmental age showing the most accurate fetal forms throughout development. A concerted effort was made to use images and material in which the human embryo or fetus did not undergo any known harm.

Page last updated on November 23, 2023
Sperm-egg fusion
Sperm-egg fusion