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MRC-5, human embryonic lung fibroblasts, induce the duplication of the developing chick limb bud
Abstract:
The anteroposterior (A-P) axis pattern of the chick limb is likely to be controlled by a small region of mesenchyme cells at the posterior margin of the limb bud (ZPA, zone of polarizing activity). In this study, we found that MRC-5 fibroblast cells had the capacity for duplicated-pattern formation of the chick limb along the A-P axis when grafted to the anterior region of the limb bud. MRC-5 cells were effective only during pre-limb bud stages, and the leg bud was more responsive than the wing bud. Grafted cells remained at the base of the limb bud when limb development proceeded. These results suggest that the products of MRC-5 cells are involved in three possible processes of duplicated-pattern formation: induction of the polarizing activity; maintenance of this activity, which is present weakly at pre-limb bud stages; and determination of A-P axis as the ZPA factor(s). By allowing the use of a small number of cells of embryonic tissues with polarizing activity, the analysis of duplicate formation with the MRC-5 cell line provides a powerful tool for elucidating the molecular nature of the ZPA.
Insights
MRC-5 fibroblast cells can induce duplicated chick limb patterns along the anteroposterior axis. These cells are effective in pre-limb bud stages, suggesting a role in establishing limb polarity.
Area of Science:
- Developmental biology
- Limb development
- Cell biology
Background:
- The anteroposterior (A-P) axis of chick limb development is regulated by the zone of polarizing activity (ZPA).
- Understanding the molecular mechanisms of ZPA function is crucial for deciphering limb patterning.
- Investigating cell lines capable of influencing A-P axis formation can provide insights into ZPA activity.
Purpose of the Study:
- To investigate the potential of MRC-5 fibroblast cells in inducing duplicated limb patterns.
- To determine the effective stages and limb types for MRC-5 cell-mediated pattern duplication.
- To elucidate the role of MRC-5 cell products in anteroposterior axis determination.
Main Methods:
- Grafting MRC-5 fibroblast cells to the anterior margin of developing chick limb buds.
- Observing and analyzing limb pattern formation following cell transplantation.
- Assessing the timing and responsiveness of limb buds to grafted cells.
Main Results:
- MRC-5 fibroblast cells induced duplicated limb patterns along the A-P axis when grafted to the anterior limb bud.
- The inductive capacity of MRC-5 cells was limited to pre-limb bud stages.
- Leg buds exhibited greater responsiveness to MRC-5 cell grafts compared to wing buds.
- Grafted MRC-5 cells persisted at the base of the developing limb bud.
Conclusions:
- MRC-5 cell products may induce, maintain, or determine the anteroposterior axis by acting as ZPA factors.
- The MRC-5 cell line serves as a valuable tool for studying the molecular basis of ZPA activity and limb patterning.
- This research offers a novel approach to understanding the fundamental processes of embryonic limb development.