Development of Limbs (4th to 8th Week)
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
Migration of Lateral Plate Mesoderm
SEM of Limb Bud from a Day 29 Embryo
Normal Chick Limb Anatomy
Role of Apical Ectodermal Ridge and Mesodermal Core in Limb Bud Development
Formation of Supernumerary Limbs
Meromelia
The Generation of Limbless Vertebrates Snake Axial Skeleton
Formation of Snake Hindlimb
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 20-25 days.
Patterning of the Antero-Posterior Axis: Transplantiaton of ZPA
Evidence for a Morphological Gradient Established by the ZPA
Retinoic Acid Transplantation Experiment
Retinoic acid induces mirror polydactyly
Whole mount of chick embryo showing expression of Sonic Hedgehog
Polydactyly showing partial duplication of the right foot and toes
Establishment of the Dorso-Ventral Axis
Forelimb versus Hindlimb Signals
Time Course of Upper and Lower Limb Development
Formation of the Hand
Webbed Hand (Syndactyly)
Nucleoli Differences in Chick and Quail
Quail-chick Cell Tracing Experiment
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
Bone Development
X-rays of Bone Growth
Cogenital Anomalies of Limb 1.) Reduction defects Meromelia Amelia 2.) Duplication defects Polydactyly 3.) Dysplasia Syndactyly Gigantism
Critical Periods in Human Prenatal Development