Evolutionary Anatomy of Tetrapod Limbs Quiz

The type of limb that forms when a new limb bud is induced with an FGF secreting bead depends on which TBX gene is expressed in the limb bud. Each TBX gene is responsible for specific limb patterns and structures.

FGF10 is known to specifically induce the overlying ectoderm to form the apical ectodermal ridge (AER) during limb development. The AER is essential for limb outgrowth and patterning in vertebrates.

The apical ectodermal ridge (AER) is a structure that runs along the distal margin of the limb bud and plays a crucial role in directing the outgrowth and pattern formation of the limb during development.

The apical ectodermal ridge (AER) functions as a major signaling center in limb development by maintaining the underlying mesenchyme, interacting with proteins specifying axes, and instructing differentiation. It does not regulate blood circulation, control temperature, or produce hormones for limb development.

The correct answer explains that the PZ is the progress zone below the apical ectodermal ridge (AER), while the incorrect answers provide misleading information about different zones or areas related to limb development and bone tissue.

The correct experiments described in the answer show specific results regarding the interactions between the AER and the PZ, all of which have been observed and documented in scientific studies.

Dorsalized embryos lack the necessary signals for limb development due to the absence of the dorsal-ventral junction and AER formation, leading to limb development cessation.

The correct pattern of bones in tetrapods involves stylopod (proximal bones such as humerus/femur), zeugopod (middle bones such as radius/ulna, fibula, tibia), and autopod (distal bones such as fingers and toes). The incorrect answers provide variations that do not accurately describe the common pattern found in tetrapod bones.

The correct answer describes the axes of the vertebrate limb as proximal-distal, stylo-zeugo-autoant-pos, and dorsal-ventral. The incorrect options either mix up the terms or provide entirely different axes, making them incorrect choices.

Pattern formation refers to the specific process described in the correct answer, where cells organize into specific structures during embryonic development.

Limbs do not form randomly or at the same location on every individual, and they are not based on diet. There are specific positions where limbs are generated in the body.

These incorrect answers do not accurately reflect the experiments used to determine which areas limbs form.

A limb field refers to the entire area where a limb can develop in organisms like animals and humans.

Limb development begins with the proliferation of mesenchymal cells from specific regions as described in the correct answer. The incorrect answers provided do not align with the actual process of limb development.

In tetrapods, including mammals, birds, reptiles, and amphibians, four limbs are formed which are always opposite each other across the midline. Limbs develop at different somite locations but are constant with respect to hox gene expression along the Anterior-Posterior (A-P) axis.

Forelimb buds in different species are marked by specific hox genes and corresponding vertebrae, with hoxc-6 marking the first thoracic vertebrae. This positioning is crucial for development and proper structure formation.

The correct answer highlights the ability of the limb field to regulate for lost or added parts through a specific process. The incorrect answers provide contrasting statements that do not align with the known functioning of the limb field in development.

The correct answer is lateral plate mesoderm because it is responsible for signaling the development of limb buds during embryogenesis.

During embryonic development, lateral plate mesoderm cells give rise to the prospective limb skeleton, not red blood cells, liver cells, or muscle cells. This process is essential for the formation of the skeletal structure in limbs.

During early limb bud development, the lateral plate mesoderm cells secrete fgf10, which is capable of initiating limb-forming interactions between ectoderm and mesoderm.

FGF10 is indeed initially expressed throughout the lateral plate mesoderm, making the statement True.

FGF 10 is restricted to limb bud sites in the lateral plate mesoderm through WNT formation, specifically Wnt2B in the chick forelimb region and WNT8C in the hindlimb area. Other mechanisms such as inhibition by retinoic acid, activation by Hox genes, and direct interaction with neural crest cells do not play a significant role in this restriction process.

FGF8 activates Shh specifically at the POS portion of the limb bud, playing a crucial role in limb development and patterning.

The AER, or apical ectodermal ridge, is a structure in the developing limb of a vertebrate embryo that contains specific signaling molecules vital for proper limb growth and development.

FGF10 from the hindlimb and forelimb regions induces FGF8 expression in the Apical Ectodermal Ridge (AER) during limb development.

FGF 10 signals the ectoderm during development, playing a crucial role in the formation of various tissues and organs in the human body.

The correct factors that induce continued mesodermal expression of FGF 10 are Wnt3a and ectoderm pathway FGF8 from AER.

TBX4 is a gene that specifically specifies hindlimb buds during embryonic development, playing a crucial role in limb formation.