EXPRESSION OF THE RNA COMPONENT OF TELOMERASE DURING HUMAN-DEVELOPMENT AND DIFFERENTIATION

We used a radioactive in situ method to study expression of the RNA co mponent of human telomerase (hTR) during normal human development and differentiation using archival tissues. In embryonic tissues, the high est and most uniform expression was present in undifferentiated neuroe pithelium. Expression was stronger in immature epithelium than in acco mpanying immature mesenchyme, Differentiation of most tissues was acco mpanied by decreased or absent expression. Except for testis and adren al, the adult pattern of expression was present by the 10th postnatal week. In adult tissues, high expression was present in the testis (pri mary spermatocytes and Sertoli cells), moderate expression was present in lymphoid follicles (germinal centers), and weak expression was pre sent in epithelia (regenerative cells) but was absent in the nervous s ystem and mesenchymal derived tissues. Expression in adult tissues was predominantly limited to dividing cells, although certain differentia ted postmitotic cells expressed the hTR, Our studies demonstrate the c omplex interrelationship of hTR expression with human development, dif ferentiation, and cell division.