CD34-positive primitive vessels and other structures in human fetuses: An immunohistochemical study

Conclusion. CD34-positive mesenchymal tissues are likely to play a critical role in the pattern formation of laryngeal and pharyngeal walls. In the ear, nose, and throat regions, a future clinical relevance may be found in their use for muscle repair and regeneration. Objectives. CD34 is a well-known marker of progenitor cells of blood vessels and stromal tissues. Thus, CD34-positive cells have recently been used clinically in the field of vascular and orthopedic biotechnology because of their capacity to assist regeneration of injured tissues. However, to our knowledge, the in situ distribution of CD34-positive cells has not yet been described in the human fetus, with the exception of a few organs. The purpose of this study was to describe the location of CD34-positive cells in the head and neck regions. Methods: Immunohistochemistry for CD34 was carried out using seven human fetuses (12 and 15 weeks of gestation). Results: CD34-positive structures showed a vessel-like appearance and were regularly arrayed along the nasal, oral, pharyngeal, and laryngeal mucosal epithelia, whereas in the laryngeal and pharyngeal striated muscles they were distributed diffusely as fibrous tissues such as the fascia and perimysium.