Immunocytochemical evidence for the presence and location of the neurotrophin-Trk receptor family in adult human preovulatory ovarian follicles.

OBJECTIVE: This study was undertaken to evaluate the presence or absence of neurotrophins and their respective receptors within adult human preovulatory follicles. STUDY DESIGN: Prospective study of neurotrophins and their receptors in follicular cells and unfertilized oocytes from women undergoing aspiration for in vitro fertilization/intracytoplasmic sperm injection. Cells (mural and cumulus granulosa cells, unfertilized oocytes) were examined for immunocytochemical staining of neurotrophin and receptor proteins. RESULTS: Mural and cumulus granulosa cells were positive for BDNF, NT-4/5, NT-3, and NGF, as well as for Trk B, Trk C, and Trk A receptors. Unfertilized oocytes were positive for Trk B, Trk C, and Trk A receptors. CONCLUSION: Neurotrophins and their respective receptor proteins are present within the mural and cumulus granulosa cells of adult human preovulatory follicles. Neurotrophin receptors are present in human unfertilized oocytes. The location of the neurotrophins and their receptors suggest both an autocrine and paracrine function within the adult human ovarian follicle.

Impact of retained embryos on the outcome of assisted reproductive technologies.

OBJECTIVE: To assess the impact of embryo retention in the embryo transfer catheter followed by "immediate" retransfer on pregnancy outcome in women undergoing assisted reproduction. DESIGN: Retrospective analysis of embryo transfer following in vitro fertilization. SETTING: Assisted reproductive technology practice in a university in vitro fertilization program. PATIENT(S): In vitro fertilization charts for 1,812 embryo transfer cycles representing 1,139 patients between January 1997 and March 2002 were reviewed. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Pregnancy rate, implantation rate, delivery rate. RESULT(S): Three embryo transfer cycles were excluded from analysis because of missing data, leaving 1,364 embryo transfers during oocyte recovery cycles and 445 embryo transfer cycles using thawed embryos. Seventy-one embryo transfers (3.9% of all transfers) were complicated by finding retained embryos after the initial embryo transfer-all retained embryos were immediately retransferred. There was no difference in the frequency of retained embryos during oocyte retrieval versus thawed embryo cycles. The pregnancy, implantation, and delivery rates per embryo transfer were not negatively affected by embryo(s) retained in the transfer catheter. Age, fresh versus frozen embryo, use of ultrasound during the procedure, or transferring physician did not influence pregnancy outcome. CONCLUSION(S): Immediate retransfer of embryos retained in the catheter following the initial transfer attempt did not have an adverse effect on pregnancy outcome.

Neurotrophin-4/5 and neurotrophin-3 are present within the human ovarian follicle but appear to have different paracrine/autocrine functions.

Neurotrophins are a family of soluble polypeptide growth factors widely recognized for their role in the mammalian nervous system. We first reported the unique presence of one neurotrophin, brain-derived neurotrophic factor (BDNF), in the follicular fluid of the human ovarian follicle. The BDNF receptor, Trk B, was identified in mouse oocytes, and BDNF accelerated first polar body extrusion in vitro. In the present study, we examined human follicular fluid and mouse immature oocytes to determine whether another Trk B ligand, neurotrophin-4/5 (NT-4/5), is present within the ovarian follicle and if so, whether it demonstrates activity similar to that of BDNF. We also examined whether a non-Trk B neurotrophin ligand, neurotrophin-3 (NT-3), is present within the follicle and has a possible role in oocyte maturation. NT-4/5 and NT-3 were noted to be present in all human follicular fluid samples aspirated from follicles of women undergoing in vitro fertilization. NT-4/5, but not NT-3, significantly promoted mouse oocyte polar body extrusion. Trk C receptors were not noted to be present in mouse oocytes. This study demonstrates for the first time that NT-4/5 and NT-3 are present in the follicular fluid of the human ovary. These data suggest that NT-4/5, like BDNF, promotes oocyte nuclear maturation. In contrast, NT-3 does not promote oocyte maturation but may contribute to follicle-oocyte maturation by mechanisms not yet identified.

Early follicular serum müllerian-inhibiting substance levels are associated with ovarian response during assisted reproductive technology cycles.

OBJECTIVE: To test the hypothesis that the concentration of early follicular phase serum müllerian-inhibiting substance (MIS) is associated with ovarian response in women undergoing ovulation induction in preparation for assisted reproductive technology (ART). DESIGN: Retrospective analysis of frozen day 3 serum samples. SETTING: Academic ART program. PATIENT(S): One sample of frozen day 3 serum from women with < or = 6 retrieved oocytes (n = 28) compared with women with > or = 11 oocytes retrieved (n = 79) in preparation for IVF. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Comparison of day 3 serum MIS levels between two groups of women. Other comparisons included maximum serum E(2) concentrations, number of retrieved oocytes, and percentage of mature oocytes between groups. RESULT(S): Mean serum MIS concentrations were 1.0 +/- 0.4 ng/mL compared with 2.5 +/- 0.3 ng/mL, or more than a 2.5-fold greater serum concentration of MIS in the group with > or = 11 oocytes retrieved compared with in the group with < or = 6 retrieved oocytes. CONCLUSION(S): These data demonstrate an association between early follicular phase serum MIS and the number of retrieved oocytes. Higher day 3 serum MIS concentrations were associated with greater number of retrieved oocytes.

Brain-derived neurotrophic factor: a novel human ovarian follicular protein.

Neurotrophins are a family of soluble polypeptide growth factors widely recognized for their roles in the mammalian nervous system. One such neurotrophin, brain-derived neurotrophic factor (BDNF) was originally described in the nervous system but has now been shown to be expressed in a variety of nonneuronal tissues including endocrine tissues. We examined the human ovarian follicle for its possible secretion of BDNF and further studied mouse oocytes to determine BDNF's possible influence upon oocyte maturation. In a series of experiments derived from human specimens from in vitro fertilization following oocyte retrieval, BDNF was detected in human follicular fluid. To define the source of BDNF, cumulus granulosa cells (the cells that immediately surround the developing oocyte) were grown in cell culture for 1-2 d. BDNF protein increased over 24 h in the culture medium. Moreover, the release of BDNF was enhanced upon stimulation with cAMP or forskolin, an activator of cAMP. In contrast, mural granulosa (cells lining the follicle), oocytes, and embryos did not release appreciable quantities of BDNF. To examine possible targets of BDNF, mouse studies were used to localize the BDNF receptor, Trk B, immunocytochemically. The receptor was present on the surface of isolated oocytes. Moreover, BDNF promoted mouse oocyte maturation in culture. These experiments demonstrate for the first time the presence and secretion of BDNF from follicular cells in the human ovary and suggest a possible role for BDNF in the regulation and modulation of oocyte maturation.