PMSG-primed and hCG-triggered rat ovaries were exposed to nicotine and its major metabolite, cotinine, using in vitro and in vivo experimental approaches. In vivo, a dose-dependent reduction in oocytes within the fallopian tube was noted in nicotine treated rats (6.25 ng/g animal weight, P < 0.001). Serum estradiol concentrations were also reduced in rats receiving nicotine (P < 0.04). There were no significant differences in weight gain. Cotinine had no effects. In vitro, nicotine also caused a dose-dependent reduction in oocytes in the collection chamber (P < 0.0001). Estradiol levels in nicotine-treated perfusions were reduced and reached statistical significance at 7 h (P < 0.003). The in vitro fertilization rate was reduced for nicotine-treated perfusions exposed to 1.43 pg/mL of nicotine (P < 0.001). Cotinine had no effect in vitro. We conclude that nicotine inhibits ovulation, estradiol production, and fertilization both in vivo and in vitro in rat models of ovulation. Cotinine did not affect these parameters. These effects of nicotine are notably independent of nicotine's known effect on the midcycle gonadotropin surge.

Animals↗

PubMedDate not supplied

Effect of fluctuations in temperature encountered during handling and shipment of human cryopreserved semen.

The effect of temperature fluctuations which cryopreserved spermatozoa may undergo during routine shipping and handling was evaluated in sperm frozen with two cryoprotectants. Sperm frozen in TEST-yolk buffer maintained motility better than those frozen in glycerol solution in all studies. Sperm motility was significantly compromised in samples stored more than one day in dry ice, regardless of the cryoprotectant, and more than two days in a liquid nitrogen shipping dewar if frozen in glycerol solution. Sperm motility was not compromised following exposure to room temperature for up to 3 min if TEST-yolk buffer was used as the cryoprotectant, but was compromised following 1 min exposure using glycerol cryoprotectant. This study describes the limits of non-ideal conditions that spermatozoa may undergo during shipping and handling, and demonstrates the effects of the cryoprotectant on those limits.

Cryopreservation↗

PubMedDate not supplied

Role of the cumulus in the selection of morphologically normal sperm and induction of the acrosome reaction during human in vitro fertilization.

This study analyzed the role that the cumulus oophorus may play in the selection of morphologically normal sperm and the induction of the acrosome reaction. Using the triple stain technique, sperm morphology and acrosomal status were compared between sperm that penetrated the cumulus during in vitro fertilization and sperm from outside the cumulus. The mean percentage of morphologically normal sperm in the samples was 54 +/- 2.8 and increased (p < 0.05) to 67 +/- 2.6 within the cumulus. Tapered sperm were significantly decreased (p < 0.05) within the cumulus. The percentage of sperm undergoing the acrosome reaction significantly increased (p < 0.05) from 14.5 +/- 1.5 to 24.5 +/- 1.9 when incubated with a cumulus mass, and further increased to 49 +/- 3.3 when incubated with mature, expanded cumulus tissue containing an oocyte. These data indicate that human cumulus oophorus plays an active role in the selection of morphologically normal sperm, and influences the ability of the sperm to undergo the acrosome reaction.

Acrosome↗