Hypertrophic differentiation of cartilage is initiated in the middle of the anlagen and spreads outward while cartilage cells near the PA 452 extremities continue to proliferate and support longitudinal growth of the developing skeletal elements. As the limb skeleton grows, the segmentation of cartilage template takes place. During this process, the incipient joint site loses cartilaginous property and forms a specialized tissue called the interzone. The interzone acts as a signaling centre and instructs the neighbouring cells of the cartilaginous template to achieve distinctive property to become articular cartilage i.e., permanent cartilage. Thus from the condensing mesenchyme of limb bud both bone and articular cartilage are formed. Whitfield referred to the primary cilium of cartilage and bone cells as the mechanosensory toggle switch. In this article Whitfield raises several important questions e.g. given the cilium of cartilage and bone is a mechanosensory device how is it toggled or what is the nature of the signal it sends and how this signaling mode is different from that of other mechanosensing systems. Cdh23 which our screen reports to be expressed in limb cartilage and from other reports is known to mediate ciliary mechanotransduction might be a good candidate in the above context. The expression patterns reported herein would thus serve as guidelines to formulate testable hypothesis in different developmental contexts. To elaborate, we would like to use some of the kidney expression patterns elucidated OMDM-2 through this study and demonstrate how this expression information can be used in the light of the current understanding of molecular basis of kidney development to develop novel hypotheses. Kidneys are components of the genito-urinary system. The intermediate mesoderm generates the entire genito-urinary system including the kidneys. The existing literature suggests that through multiple rounds of sorting of IM cells different structural components of kidney are formed. Cells within these newly formed structures proliferate and differentiate to generate tissues that are capable of supporting the physiological function of kidney. The first morphologically distinct feature arising out of the IM is the nephric duct. As development progresses at the posterior end of the nephric duct a small tissue outgrowth, the ureteric bud, is induced. Tip of the ureteric bud emerging from the nephric duct induces the neighbouring mesenchyme to aggregate around itself and form a distinct structure called the cap mesenchyme. The cap mesenchyme is the source of all epithelial components of the nephron. Cells of the cap mesenchyme aggregate, proliferate, lose their mesenchymal properties and acquire epithelial character through mesenchymal-to-epithelial transition.