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#mosaic development

2 public questions tagged with this topic.

Specification Determination-l

Which of the following organisms primarily exhibits mosaic development?

Caenorhabditis elegans displays highly invariant mosaic development with essentially complete cell lineage mapped. Early cleavages partition maternal PAR polarity proteins and localized mRNAs including mex-3, skn-1, pie-1 and p granules, conferring autonomous fate to AB versus P1 descendants. Isolated blastomeres produce only lineal descendants and fail to generate entire worm, reflecting determinant-driven programming with limited regulation. Conditional inductions occur sparingly, such as MS signaling via GLP-1/Notch inducing AB-derived pharynx and P2 inducing EMS via Wnt/Src to segregate gut versus mesoderm, but overall architecture relies predominantly on autonomous mosaic logic rather than regulative interactions.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 4: Mosaic Development in C. elegans.

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Specification Determination-l

Which of the following statements about mosaic development is correct?

Mosaic development emerges when embryonic pattern arises primarily from intrinsic determinants rather than extrinsic cell communication, defining autonomous specification. Blastomeres become committed early after cleavage, and overall architecture is sum of independent lineages like tiles in a mosaic. Organisms such as C. elegans, tunicates and many spiralians exemplify this mode; ablation of a blastomere permanently eliminates corresponding tissues without replacement by neighbors. Because fate depends on internal inheritance rather than interaction, regulative capacity is limited. Later developmental stages incorporate limited conditional induction to refine certain tissues, but underlying logic remains determinant-driven.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 3: Mosaic Development and Autonomous Specification.

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