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To gain insight into early reproductive processes we have prospectively designed ovum donation protocols to elucidate several phenomena relating to embryo implantation and pregnancy sustenance. Artificial endometrial cycles with variable follicular phases were induced in 60 recipients by sequential estrogen and progesterone. A total of 964 oocytes were retrieved throughout 43 ovum donation attempts, for an average of 22.4 (range, 16-41) eggs/retrieval. The overall delivery rate per egg retrieval (donors and recipients combined) was 72.1% (31 of 43). The shortest estrogen stimulation (short follicular phase) resulting in ongoing pregnancies was 5 days in duration, while the longest (long follicular phase) was 35 days in duration before progesterone initiation. Utilization of variable length follicular phases, artificially extended the stage of endometrial receptivity to over 4 weeks. To assess the window of implantation, same age embryos were transferred onto endometrium of different maturational stages. Pregnancies were documented with embryo transfers between luteal day 1 (day 15) to luteal day 6 (day 20), extending the window of implantation in the human to at least 6 consecutive days. To evaluate the relative contribution of oocyte quality and endometrial receptivity to pregnancy outcome, common source ova were transferred onto endometrium with variable hormonal exposure. Despite the drastically different follicular phase estradiol levels and periods of exposure, similar delivery rates were attained in donor cycles (29.4%) and recipient cycles during short follicular phases (29.6%). Slightly higher delivery rates (39.4%) were observed with long follicular phases. The comparable pregnancy rates in donors and recipients are attributed to the common source oocytes regardless of endometrial stimulation.

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Few studies have assessed the role of pituitary and gonadal hormones on age-related changes in sexual behavior in healthy men. We conducted a retrospective and prospective evaluation of sexual function and behavior in 77 healthy married men aged 45 to 74 years. The subjects were studied in the sleep laboratory for four nights with the last night devoted to sequential blood sampling every 20 minutes. Significant age-related decreases in sexual desire, sexual arousal and activity, and increases in erectile problems were noted. Aging was negatively correlated with bioavailable testosterone (bT), was positively correlated with luteinizing hormone (LH), and was not related to total testosterone, estradiol, and prolactin. Bioavailable testosterone, and the ratio of bT over LH showed a close association with several sexual behavior dimensions while total testosterone, estradiol. and prolactin demonstrated few or no behavioral relationships. The age-related effect of bT was, however, a more important determinant of the reported behavioral differences than were the effect of bT independent of age. There was no evidence that changes in circulating hormones contribute to erectile disorders in healthy aging men.