Objective: To identify stem cells in uteri from the fetal to the postmenopausal period.
Design: Descriptive, controlled study.
Setting: Tertiary academic medical center.
Patient(s): Forty archived uterine endometrial samples.
Intervention(s): Immunohistochemistry with c-kit/CD117, CD34, bcl-2, and Ki67.
Main outcome measure(s): Immunostaining.
Result(s): C-kit/CD117, CD34, bcl-2, and Ki67 were consistently expressed in the stroma of the basalis layer. Bcl-2 was restricted to the fetal uterine endometrium.
Conclusion(s): By studying the immunolocalization of stem cell markers (i.e., c-kit, CD34, and bcl-2), we found that stem cells are present continuously in the uterine endometrium from the fetal period. The cells seem to be located mainly in the stroma of the basalis and to be independent of hormonal regulation to avoid cyclic shedding. A small number of latent stem cells dormant in the stroma of the basalis were found to have the potential for mesenchymal differentiation.