Specification of cell fate along the proximal-distal axis in the developing chick limb bud

Abstract

Pattern formation along the proximal-distal (PD) axis in the developing limb bud serves as a good model for learning how cell fate and regionalization of domains, which are essential processes in morphogenesis during development, are specified by positional information. In the present study, detailed fate maps for the limb bud of the chick embryo were constructed in order to gain insights into how cell fate for future structures along the PD axis is specified and subdivided. Our fate map revealed that there is a large overlap between the prospective autopod and zeugopod in the distal limb bud at an early stage (stage 19), whereas a limb bud at this stage has already regionalized the proximal compartments for the prospective stylopod and zeugopod. A clearer boundary of cell fate specifying the prospective autopod and zeugopod could be seen at stage 23, but cell mixing was still detectable inside the prospective autopod region at this stage. Detailed analysis of HOXA11 AND HOXA13 expression at single cell resolution suggested that the cell mixing is not due to separation of some different cell populations existing in a mosaic. Our findings suggest that a mixable unregionalized cell population is maintained in the distal area of the limb bud, while the proximal region starts to be regionalized at the early stage of limb development.

Regulative patterning in limb bud transplants is induced by distalizing activity of apical ectodermal ridge signals on host limb cells

“…We performed some grafts of distal wing bud tips to somites and zeugopod/ hindbrain to validate the system (data not shown), confirming that the mean value of the segments obtained correlated well with the fate map of the transplanted regions (Saunders, 1948;Stark and Searls, 1973;Bowen et al, 1989;Vargesson et al, 1997;Sato et al, 2007). However, because we sometimes needed to perform heterotopic wing/leg transplantations and grafting to the HH24 wing bud is easier than to the leg bud, we soon switched to using leg bud donors only.…”

“…Stock and working solutions of DiI were prepared as described (Sato et al, 2007). A mouth pipette and a pulled capillary tube were used to apply the dye to the embryo.…”

Evolutionary and Developmental Aspects of Avian-Specific Traits in Limb Skeletal Pattern

“…In the latter model, three distinct parts, corresponding to the stylopod, zeugopod, and autopod are already specified in the very early limb bud, and the three parts grow and expand as limb development proceeds (Dudley et al, 2002;Sun et al, 2002). In fact, there is evidence for a combination of these two models, in which the proximal region is specified in the early stage and the distal region is progressively added to the tip of the limb bud (Sato et al, 2007;Cooper et al, 2011;Rosello-Diez et al, 2011). The AER also appears to be involved in controlling the number of digits and phalanges.…”

Estimating the spatiotemporal pattern of volumetric growth rate from fate maps in chick limb development

“…In the following, we first carry out the model selection for distally biased phase of volumetric growth by using the data of Sato et al (2007) …”

“…We focus on one-dimensional (1D) cell trajectories along the proximodistal (P-D) axis passing through the tip of AER during chick wing development. Although the real limb development proceeds in 3D space, this simplification is appropriate as a first step because a main direction of cell trajectory is the P-D axis (Stark and Searls, 1973;Sato et al, 2007).…”