2. Development of Limbs (4th to 8th Week)

3. Chronology of Limb Development
4 stages of Limb Development
1.) Initiation
limb bud formation
2.) Specification of limb pattern
growth of the 3 axis occurs
3.) Tissue formation and limb morphogenesis
limb elements form
4.) Growth
occurs into early adulthood

4. Migration of Lateral Plate Mesoderm

5. SEM of Limb Bud from a Day 29 Embryo

6. Normal Chick Limb Anatomy

7. Role of Apical Ectodermal Ridge and Mesodermal Core in Limb Bud Development

8. Formation of Supernumerary Limbs

9. Meromelia

10. The Generation of Limbless Vertebrates
Snake Axial Skeleton

11. Formation of Snake Hindlimb

12. Is regeneration of limbs possible?
Newt Limb Regeneration
                                             
This is a time-lapse sequence showing
the stages of newt limb regeneration.
The surgical amputation was at the
level of the humerus. The pictures
show the wound-healing,
de-differentiation, blastema and
re-differentiation stages of
regeneration. Total time shown is
approximately days.

13. Patterning of the Antero-Posterior Axis: Transplantiaton of ZPA

14. Evidence for a Morphological Gradient Established by the ZPA

15. Retinoic Acid Transplantation Experiment

16. Retinoic acid induces mirror polydactyly

17. Whole mount of chick embryo showing expression of Sonic Hedgehog

18. Polydactyly showing partial duplication of the right foot and toes

19. Establishment of the Dorso-Ventral Axis

20. Forelimb versus Hindlimb Signals

21. Time Course of Upper and Lower Limb Development

22. Formation of the Hand

23. Webbed Hand (Syndactyly)

24. Nucleoli Differences in Chick and Quail

25. Quail-chick Cell Tracing Experiment

26. Limb Musculature Develops from Ventral and Dorsal Condensations of Somitic Mesoderm
Dorsal Muscle Mass
extensors and supinators upper limb
extensors and abductors lower limb
Ventral Muscle Mass
flexors and pronators upper limb
flexors and adductors lower limb

27. Bone Development

28. X-rays of Bone Growth

29. Cogenital Anomalies of Limb
1.) Reduction defects
Meromelia
Amelia
2.) Duplication defects
Polydactyly
3.) Dysplasia
Syndactyly
Gigantism

30. Critical Periods in Human Prenatal Development