Although theory and widespread evidence show that the evolution of egg size is driven primarily by offspring and maternal fitness demands, an additional explanation invokes sperm limitation as a selective force that could also influence egg size optima. Levitan proposed that constraints from gamete encounter in external fertilization environments could select for enlargement of ova to increase ...

We present a nulliparous woman with mild to moderate ulcerative colitis (UC) and multiple failed cycles of in vitro fertilization (IVF) in whom we achieved a successful, viable pregnancy following clinical and endoscopic UC remission. Infertile patients with inflammatory bowel disease who have failed multiple cycles of IVF should try to achieve clinical remission and mucosal healing (absence of...

background: our objective was to evaluate the effectiveness of clomiphene citrate (cc) vs. letrozole (l) plus human menopausal gonadotropin (hmg) in gonadotropin releasing hormone (gnrh) antagonist protocol in poor prognosis women with previous failed ovarian stimulation undergoing intracytoplasmic sperm injection (icsi). materials and methods: this retrospective cohort study included cycles wi...

With the introduction of intracytoplasmic sperm injection (ICSI), couples with severe male factor infertility have been able to achieve fertilization and clinical pregnancy rates comparable to other in vitro fertilization patients. However, despite the utilization of microsurgical sperm injection techniques, failure of fertilization still occurs in a few patients. How such fertilization failure...

OBJECTIVE To investigate the clinical effect of microsurgical varicocelectomy on severe oligo-asthenospermia patients failing in fertilization assisted by intracytoplasmic sperm injection. PATIENTS AND METHODS From January 2013 to August 2014, forty-nine patients with severe oligo-asthenospermia and serious varicoceles were treated by microsurgical varicocelectomy after failing in fertilizati...

BACKGROUND Failed fertilization after IVF occurs in 10-20% of cycles. Conflicting results of rescue fertilization by ICSI have been reported. We therefore compared the success rate in terms of fertilization and pregnancy of cycles in which rescue ICSI was performed with those from a matched control group of primarily ICSI cycles. METHODS Unfertilized oocytes from IVF cycles with total fertili...

In pigs, the efficiency of embryo production after intracytoplasmic sperm injection (ICSI) is still low because of frequent failure of normal fertilization, which involves formation of two polar bodies and two pronuclei. To clarify the reasons for this, we hypothesized that ICSI does not properly trigger sperm-induced fertilization events, especially intracellular Ca2+ signaling, also known as ...

OBJECTIVE To determine the usefulness of and cost-effectiveness of antisperm antibody testing in the prediction of poor fertilization rates in couples undergoing IVF. DESIGN Retrospective cohort study. SETTING A hospital-based reproductive endocrinology and infertility practice. PATIENT(S) Male partners of 251 couples undergoing IVF between 1992 and 1997. MAIN OUTCOME MEASURE(S) Fertili...

BACKGROUND The aim of this retrospective study is to investigate the relevance of dividing oocytes and using some for traditional in vitro fertilization (IVF) and others for intracytoplasmic sperm injection (ICSI) as of the first IVF cycle in patients with unexplained infertility who have undergone 4 intrauterine insemination (IUI) cycles which produced no pregnancies. METHODS This retrospect...

Establishment and growth of three perennial herbs and a small tussock grass were studied in an experiment that provided simulated rainfall of 6 mm week 1 or 25 mm once per month and nitrogen fertilization in combination with the different simulated rainfall regimes. Wild onion, Allium macropetalum, failed to establish in plots receiving 25 mm month 1 simulated rainfall. The perennial composite,...