Cell Biology. In the article “Impairing follicle-stimulating hormone (FSH) signaling in vivo: Targeted disruption of the FSH receptor leads to aberrant gametogenesis and hormonal imbalance” by Andree Dierich, M. Ram Sairam, Lucia Monaco, Gian Maria Fimia, Anne Gansmuller, Marianne LeMeur and Paolo Sassone-Corsi, which appeared in number 23, November 10, 1998, of Proc. Natl. Acad. Sci. USA (95, 13612–13617), the authors request that the following correction be noted: In Fig. 2 appearing on page 13614, the genotype identification for testicular histology in panels C and D were shown reversed. The correct identification is −/− for panel C and +/+ for panel D. The fifth sentence of the figure legend should read as follows: “Histological sections at lower (E) and higher (D) magnification of the seminiferous tubuli from a wild-type and mutant (F and C) mouse.”