Fig. 1

Immunohistochemical localization of TRKB receptor in human and mouse ovaries; human FF level of NT-4. a Tropomyosin-related kinase B (TRKB) immunoreactivity is both abundant in GCs and oocyte of 6-week-old mice preantral follicles (arrowhead). In the primary follicle (arrow), the expression of TRKB in GCs is slightly lower than in oocytes. The difference is more significant in primordial follicles (*). b TRKB immunoreactivity is present in oocytes of primary follicles and primordial follicles of 2-week-old. GCs contain lower but detectable levels of TRKB protein. c, d Detection of NGF immunoreactivity in oocytes of human primary or primordial follicles (c) and preantral follicles (d). a-d These are representative images of three independent experiments. No signal was detected in the negative control for either set of prime. e Western blot detection of human cumulus cells, mouse ovary, mouse cumulus cells and mouse somatic granulosa cells of TRKB receptors. f FF level of NT-4 from 49 women with different oocyte maturation rates when undergoing IVF/ICSI. *, P < 0·05