UNSW Embryology

Beginnings, Growth and Development

© Dr Mark Hill (2006)

Acknowledgements

Carnegie stage 20

Facts: Week 8, 51 - 53 days, 18 - 22 mm

View: Lateral view. Amniotic membrane removed.

Identify: straightening of trunk, pigmented eye, eyelid, nose, external acoustic meatus, scalp vascular plexus, digital rays, liver prominance, thigh, ankle, foot plate, umbilical cord

Events

Ectoderm: sensory placodes, lens pit, otocyst, nasal pits moved ventrally, fourth ventricle of brain

Mesoderm: heart prominence, ossification continues

Head: forebrain, eye, external acoustic meatus

Body:straightening of trunk, heart, liver, umbilical cord

Limb: upper limbs longer and bent at elbow, foot plate with digital rays, wrist, hand plate digital rays begin to separate

Embryo Cross-sections

Lab classes originally had Stage 22 cross-sections displayed here, these are now on the Stage 22 page. The overall concepts of development are the same, organogenesis in the late embryo, showing the late embryonic stages of development.

Glossary of Terms

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

Next

Link to next page in this Practical 11 - Stage 21

Quick Movie Links

Movie of Growth through the Embryonic period (this shows a human embryo growing, all images are to scale)

Human Development (3 Mb, this is a large movie, images are not to scale)

Movie of Limb Growth(this shows development of the human arm from bud to paddle, to hand with arm)

Movie of Mouse Embryo Growth (this shows a mouse embryo growing)

Movie of Rotating Embryo(this shows an early embryo from all angles)

All Moviesthis shows many different ways of looking in at changes in different embryos.

UNSW Embryology ISBN: 0 7334 2321 3

UNSW CRICOS Provider Code No. 00098G