There are multiple definitions:

1. Heart and Estrogen/progestin Replacement Study(English)

   • PPAR, SARM, SERM, SPRM
   • Estrogen, Clinical trials
   • https://doi.org…/jama.280.7.605

2. Hertwig’s epithelial root sheath(English)

   • the inner layer of HERS is an apical extension of the ameloblastic layer in the crown. A number of studies now indicate that the cells of HERS have a secretory stage similar to the ameloblasts. In humans, amelogenin has been demonstrated at the apical ends of the roots of developing teeth
   • AP, AR, BMP, BMP-2, BMPR, BSP, CAP, CP-23, DF, EMD, HDFC, STRO-1, DiI, IEE, OEE
   • Cell biology, Dentistry, Cytometry / cytology
   • https://doi.org…0441-007-0397-3
   • https://doi.org…0470515303.ch17
   • https://doi.org….1111/jre.12003