Osteoblasts pattern endothelium and somatosensory axons during zebrafish caudal fin organogenesis

Skeletal elements frequently associate with vasculature and somatosensory nerves, which regulate bone development and homeostasis. However, the deep, internal location of bones in many vertebrates has limited in vivo exploration of the neurovascular-bone relationship. Here, we use the zebrafish caudal fin, an optically accessible organ formed of repeating bony ray skeletal units, to determine the cellular relationship between nerves, bones and endothelium. In adult zebrafish, we establish the presence of somatosensory axons running through the inside of the bony fin rays, juxtaposed with osteoblasts on the inner hemiray surface. During development we show that the caudal fin progresses through sequential stages of endothelial plexus formation, bony ray addition, ray innervation and endothelial remodeling. Surprisingly, the initial stages of fin morphogenesis proceed normally in animals lacking either fin endothelium or somatosensory nerves. Instead, we find that spr osteoblasts are required for endothelial remodeling and somatosensory axon innervation in the developing fin. Overall, this study demonstrates that the proximal neurovascular-bone relationship in the adult caudal fin is established during fin organogenesis and suggests that ray-associated osteoblasts pattern axons and endothelium.

Automated summary

This study investigates the cellular relationship between nerves, bones, and endothelium using the zebrafish caudal fin as a model. The researchers found that in adult zebrafish, somatosensory axons run through the inside of the bony fin rays, juxtaposed with osteoblasts on the inner hemiray surface. During development, the caudal fin progresses through sequential stages of endothelial plexus formation, bony ray addition, ray innervation, and endothelial remodeling. They also discovered that spr osteoblasts are required for endothelial remodeling and somatosensory axon innervation in the developing fin.