A surgical pathologist examining a biopsy from a healing skin laceration (day 7 post-injury) identifies numerous fibroblasts, proliferating capillary loops, and a loose extracellular matrix. The new blood vessels in this tissue show which of the following characteristics compared with mature vessels?

• A Thick, collagen-rich basement membranes and tight junctions
• B Fenestrated endothelium with prominent pericytes
• C Abundant smooth muscle in the media with laminar flow
• D Leaky fenestrations and poor investment of pericytes ✓

Explanation

Newly formed capillaries in granulation tissue are characteristically leaky due to incomplete basement membranes and deficient pericyte coverage, which explains the edema and weeping seen in healing wounds. As maturation proceeds over weeks, pericytes are recruited (driven by PDGF) and the basement membrane consolidates. Fenestrated endothelium is a feature of mature sinusoids and specialized organs, not immature healing vessels.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.