Hypothalamic-pituitary suppression with oral contraceptive pills does not improve outcome in poor responder patients undergoing in vitro fertilization-embryo transfer cycles.

PURPOSE: To evaluate and compare the use of OCP with GnRHa for hypothalamic-pituitary suppression in poor responder IVF patients. METHODS: Retrospective analysis of IVF-ET cycles of poor responders. Hypothalamic-pituitary suppression with OCP (Group I, n = 29) or GnRHa (Group II, n = 52), followed by stimulation with gonadotropin, oocyte retrieval, and embryo transfer. Baseline characteristics and cycle outcomes were compared. RESULTS: 73 women underwent 81 cycles from 1/1/1999 to 1/1/2000. Baseline characteristics were similar. 31/81 (38%) cycles were cancelled (Group I, 14/29 (48%) vs. Group II, 17/52 (33%), NS). Cycle outcomes including amount of gonadotropin, number of eggs retrieved, number of embryos transferred, and embryo quality were similar. Patients in Group I required fewer days of stimulation to reach oocyte retrieval. Pregnancy outcomes were similar in the two groups. CONCLUSION: Our retrospective analysis revealed no improvement in IVF cycle outcomes in poor responders who received OCPs to achieve hypothalamic-pituitary suppression instead of GnRHa.

Ultrarapid freezing (URF) of mouse and human preembryos: a modified approach.

Ultrarapid freezing (URF) employs a short one-step exposure of preembryos to cryoprotectant followed by immersion into liquid nitrogen. Higher concentrations of dimethyl sulfoxide (DMSO) have been associated with improved embryo survival. We compared two different concentrations (3.5 and 4.5 M) of DMSO for freezing of mouse preembryos. The postthaw survival for mouse preembryos was 88% (3.5 M DMSO) and 93% (4.5 M DMSO), respectively (ns). Blastocyst formation occurred in 88% of the surviving URF preembryos. We also used URF to freeze a small series of human preembryos. Four of the thirty-eight patients became pregnant following transfer of URF preembryos. Two were term pregnancies and two are ongoing. URF is simpler and less expensive than other methods and its use with human preembryos warrants further evaluation.

Ion pump ATPase inhibitors block the fertilization of zona-free mouse oocytes by acrosome-reacted spermatozoa.

The acrosome reaction was induced in nearly 100% of mouse spermatozoa with dibutyryl cyclic guanosine monophosphate (dbcGMP) before ouabain treatment. Acrosome-reacted spermatozoa could not penetrate the zona pellucida, but readily fertilized zona-free eggs. Exposure to ouabain at concentrations as low as 10(-7) M had a noticeable inhibitory effect upon fertilization. Similar results were obtained with a second ATPase inhibitor, digoxin. These results show that ion-pump inhibitors block the union of gametes which are otherwise fully competent to fertilize. These findings suggest that a membrane potential maintained by ion pumps is a necessary prerequisite for gamete fusion.

Capacitated, acrosome reacted but immotile sperm, when microinjected under the mouse zona pellucida, will not fertilize the oocyte.

We have devised a procedure for mechanically inserting intact, acrosome reacted spermatozoa under the mouse zona pellucida, and have examined the ability of sperm so inserted to fertilize the mouse oocyte. Sperm immobilized by a variety of different methods are unable to fertilize the egg, despite the fact that electron microscopy confirms that they are acrosome reacted. Control experiments show that the oocytes are capable of being fertilized by motile sperm after the microinjection procedure, and that the immobilized sperm are able to form male pronuclei after injection directly into the ctyoplasm. These results indicate that in addition to its importance for penetration of egg investments, sperm motility is required for fusion of the gametes. Alternatively, the findings suggest that the enzymatic machinery required for sperm motility is very similar to that utilized for gamete fusion, and that destruction of one is likely to lead to inactivation of the other.