UNSW Embryology

Beginnings, Growth and Development

© Dr Mark Hill (2006)

Acknowledgements

Carnegie stage 22

Facts: Week 8, 54 - 56 days, 23 - 28 mm

View: Lateral view. Amniotic membrane removed.

Identify: straightening of trunk, pigmented eye, eyelid, nose, external acoustic meatus, ear auricle, scalp vascular plexus, separated digits (fingers), thigh, ankle, umbilical cord

Events

Ectoderm:

Mesoderm: heart prominence, ossification continues

Head: nose, eye, external acoustic meatus

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

Limb: upper limbs longer and bent at elbow, foot plate with webbed digits, wrist, hand plate with separated digits

Organogenesis

These images were originally shown with the stage 20 embryo. The overall concepts of development are the same, representing a late embryonic stage of development.

Selected Stage 22 Cross-sections

The series of selected images below are from the stage 22 Human embryo. They have been selected to illustrate tissue and organ development features not visible on the surface of the embryo. Clicking the image will open the original image page. Note that there are additional highpower images available on the Serial Sections page.

Stage 22 Head

Note: developing brainstem, inner ear (cochlear), unfused palatal shelves

(More? palatal shelves)

Stage 22 Shoulder

Note: musculoskeletal system, neural (spinal cord, dorsal root ganglia, sympathetic ganglia), trachea, oesophagus

Stage 22 Chest Region

Note: heart, lungs, vasculature

Stage 22 Abdomen Region

Note:Gastrointestinal organs (liver, stomach, herniated midgut, pancreas), urogenital organs

(More? Endocrine Development - Adrenal Glands)

Stage 22 Hip Region

Note: Musculoskeletal structures (acetabulum, vertebral body, femur, developing skeletal muscles), urogenital organs

(More? external genitalia)

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 23

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