Organogenesis Flashcards
Mesenchymal cells: ____1.____ (skeletal elements + other ____2.____ ) and ____3.____ ( ____4.____ + muscle + ____5.____ )
- lateral plate mesoderm
- connective tissues
- somites
- cartilage
- partial vasculature
In chick embryos, the first signs of limb development are around the ____1.____ day after ____2.____
- third
2. the egg is laid
The ____1.____ will form the mesodermal parts of the ____2.____
- intermediate mesoderm
2. kidneys
The ____1.____ will give rise to the ____2.____
- anterior splanchnic mesoderm
2. heart
The ____1.____ part of the lateral mesoderm will develop into the ____2.____ and ____3.____
- ventral-most
- vascular system
- blood
The dermomyotome gives rise to the ____1.____ (muscle)
- myotome
The ____1.____ migrates to form the cartilage of the vertebrae
- sclerotome
The somite is patterned by signals secreted by ____1.____
- adjacent tissues
The limb has three developmental axes: (what are they?)
- proximo-distal axis
- antero-posterior axis
- dorso-ventral axis
Thickening in the ectoderm: ____1.____ or ____2.____ …runs along the boundary between ____3.____ and ____4.____ ectoderm
- apical ectoderm ridge
- apical ridge
- dorsal
- ventral
The ____1.____ part of the limb bud is the first to differentiate, and the differentiation proceeds ____2.____ as the limb bud grows out
- proximal
2. distally
The first sign of cartilage differentiation: increased local packing of the mesenchyme cells ( ____1.____ )
- condensation
T or F : during the growth phase, cartilage is replaced by bone
TRUE
During the growth phase, ____1.____ is replaced by ____2.____
- cartilage
2. bone
Genes expressed in the lateral plate mesoderm (Hox, Pitx1, Tbx4, Tbx5…..) are involved in specifying the ____1.____ and ____2.____
- position
2. type of limb
T or F : transplantation experiments in chick embryos have shown that the lateral plate mesoderm becomes determined to form limbs in their positions, long before limb buds are visible
TRUE
___1.___ is important (Tbx4 and Tbx5 control local production of ___2.___ that initiate limb development)
- FGF
2. FGFs
The apical ectodermal ridge is required for limb outgrowth and the formation of structures along the ____1.____ axis of the limb ….. and the key signal is provided by ___2.___
- proximo-distal
2. FGFs
T or F : FGF8 alone is not sufficient for normal limb development
FALSE (it is sufficient)
Outgrowth of the limb bud involves ____1.____
- oriented cell behavior
When a well-defined apical ridge is present, the limb bud’s length along the proximo-distal axis (increases/decreases) about ____1.____ , while the dimensions of its ____2.____ and ____3.____ axes are almost unchanged
increases
- three-fold
- antero-posterior
- dorso-ventral
Cell proliferation is higher ____1.____ and near the ____2.____ . . . . but the bud growth has more to do with cell polarization and oriented cell movements, and cell division in the direction of the ____3.____
- distally
- ectoderm
- apical ridge
T or F : patterning of the limb bud involves positional information and how it is being specified is still a matter of debate
TRUE
The developing chick limb bud behaves as if its future development is determined by the positions of its cells with respect to the main limb axes (the ____1.____ and the ____2.____ )
- polarizing region
2. apical ectodermal ridge
The ____1.____ or ____2.____ of a vertebrate limb bud has organizing properties almost as striking as those of the ____3.____ in amphibians
- polarizing region
- the zone of polarizing activity
- Spemann organizer
ZPA can specify positional information along the ____1.____ axis
- antero-posterior
____1.____ : any substance active in pattern formation whose spatial concentration varies and to which cells respond differently at different threshold concentrations
- morphogen
____1.____ is the ZPA morphogen
- Sonic hedgehog (Shh)
T or F : how digit identity is encoded was recently discovered
FALSE (it is not yet known)
The dorso-ventral axis of the limb is controlled by the ____1.____ (in experiments, the proximal regions of the limbs that develop have ____2.____ polarity corresponding to that of the ____3.____ , whereas the distal regions have a reversed dorso-ventral axis, with the pattern of muscles and tendons reversed and corresponding to the ____4.____ polarity of the ____5.____ )
- ectoderm
- dorso-ventral
- mesoderm
- dorso-ventral
- ectoderm
Development of the limb is integrated by interactions between ____1.____ (by ____2.____ )
- signaling centers
2. feedback control
T or F : different interpretations of the same positional signals give different limbs
TRUE
Signals are interpreted according to the ____1.____ of the responding cells (if tissue that would normally give rise to the thigh is grafted from ____2.____ part of an early chick leg bud to the tip of an early wing bud, it develops into toes with claws)
- origin
2. proximal
These results suggest that the limb bud might be able to generate a basic ____1.____ consisting of equivalent cartilaginous elements
- prepattern
A ____1.____ is a basic organization that is generated autonomously in the embryo and can be identified in advance of the latter development of a similar pattern of structures
- prepattern
T or F: The pattern that eventually develops does have to follow the prepattern exactly
FALSE (does not have to follow the prepattern exactly but may be a modified form of it)
Limb muscle is patterned by the ____1.____
- connective tissue
T or F : the initial development of cartilage, muscles, and tendons is autonomous
TRUE
