What stimulates the growth of capillary buds during the fibroblastic repair phase?

• A. Increased oxygen levels
• B. Lack of oxygen
• C. Presence of leukocytes
• D. Increased blood flow

Answer: (B)

During the fibroblastic repair phase of healing, the growth of capillary buds is primarily stimulated by a lack of oxygen. This condition, known as hypoxia, induces the body to respond by promoting angiogenesis, which is the formation of new blood vessels.

When there is insufficient oxygen, the body activates signaling pathways that enhance the production of vascular endothelial growth factor (VEGF). This growth factor plays a critical role in stimulating the proliferation of endothelial cells, which are essential for the formation of capillaries. Consequently, the development of capillary buds is a key response to improve oxygen delivery and support the healing process.

Increased oxygen levels would not signal the body to grow capillary buds, as the body would not perceive a need for additional blood supply in the presence of adequate oxygen. The presence of leukocytes, important for the inflammatory phase, primarily serves to combat infection and orchestrate the healing process but does not directly stimulate the growth of capillary buds. While increased blood flow itself is beneficial for healing, it is the relative deficiency of oxygen that acts as a primary stimulus for angiogenesis during this phase.