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In order to determine whether initial chorionic sac diameter is related to subsequent abortion, abortus karyotype, or birth weight and length, chorionic sac diameter was prospectively measured by transvaginal ultrasound in 700 singleton pregnancies before post-ovulation day 31, the latest day cardiac activity becomes detectable in normal pregnancy. Results were compared to values for the 10th to the 90th centiles, determined from 227 measurements of in-vitro fertilization and gamete intra-Fallopian transfer pregnancies. The abortion rate was 23.9% [95% confidence interval (CI) 19.2%, 28.6%] when initial chorionic sac diameter was below the 50th centile, compared to 6.9% (95% CI 4.9%, 9.4%) when equal to or above the 50th centile. Chorionic sac diameter was below the 50th centile in all anembryonic abortions and in 62% of embryonic abortions. Triploidy, trisomy 47 + 16, or trisomy 16 and the presence of satellite bodies on chromosome 22 were the only abortus karyotypes significantly associated with small chorionic sac diameter. Initial chorionic sac diameter was not associated with birth weight or length. We conclude that chorionic sac diameter is decreased in anembryonic and embryonic abortion and that normal pregnancy outcome may be expected in 90-95% of pregnancies in which initial chorionic sac diameter is equal to or above average.

The objective of this study was to determine if measurement of initial crown--rump length (CRL) is helpful in predicting low birth weight, newborn length, spontaneous abortions, or abortus karyotype. We measured CRL prospectively in 837 consecutive singleton pregnancies at the time a heart rate was first detectable with transvaginal ultrasonography and compared these measurements to normal values for the 10th through 90th centiles determined from 227 transvaginal ultrasound measurements in in-vitro fertilization and gamete intra-Fallopian transfer pregnancies with known ovulation dates. The relationship of initial CRL to birth weight and length and to abortion and abortus karyotype was analysed after all pregnancies had delivered. Initial CRL measured after the 28th post-ovulation day was predictive of subsequent abortion, but not of low birth weight or length. The abortion rate was 3.3% [95% confidence interval (CI) 1.5%, 5.1%] when initial CRL > or = 50th centile, compared to 19.4% (95% CI 15.4%, 23.4%) when < 50th centile. Initial CRL was < 50th centile in 13 out of 14 trisomic and in eight out of 10 other karyotypically abnormal aborti. These results indicate that initial CRL measured after the 28th post-ovulation day may help to identify pregnancies at increased risk of abortion due to abnormal karyotypes.

Purpose: Murine two-cell embryos (n = 5573) were cultured for 96 hr in human tubal fluid (HTF) medium (n = 2709) or alpha modification of minimum essential medium (MEM; n = 2864) through the hatched blastocyst stage from mid-1990 to mid-1991. An additional 373 embryos were cultured in MEM or HTF with 0, 1, 5, or 10 ng/ml E. coli endotoxin. A total of 17 patients had supernumerary embryos simultaneously cultured in HTF (n = 48) or MEM (n = 61). Additionally, pregnancy rates were compared for July to December 1990, when MEM was used as growth medium, and for July to December 1989, when HTF was used., Results: Blastocyst formation was higher (P < 0.001) for murine embryos cultured in MEM (blasts = 95%) compared to HTF (blasts = 70%). When cultured with endotoxin, blastocyst formation was higher (P < 0.01) for embryos cultured in MEM compared with HTF for controls and at each endotoxin level. No difference in human blastocyst development was observed in HTF and MEM. However, more MEM-cultured blastocysts were cryopreserved (P < 0.05). There also was a lower spontaneous abortion rate and a higher multiple gestation rate when embryos were cultured in MEM., Conclusion: Thus, MEM may result in healthier blastocyst development, especially when culture conditions are substandard, although this is not an acceptable substitution for meticulous technique.

Objective: To determine if preovulation endometrial thickness or pattern are related to fecundity and to use of clomiphene citrate (CC) or hMG in IUI., Design: Prospective ultrasound evaluation the day of hCG after CC alone (n = 197), hMG alone (n = 49), concurrent hMG or sequential CC and hMG (n = 205), and no medications (n = 23)., Setting: Private fertility clinic., Patients: Two hundred seventy-one patients undergoing 474 cycles of IUI., Main Outcome Measures: Endometrial thickness, pattern, per cycle fecundity, and continuing pregnancy., Results: Endometrial thickness was related to fecundity and continuing pregnancy. No pregnancies occurred when thickness was < 6 mm. The continuing pregnancy rate was 12.6% when thickness was > or = 9 mm, compared with 6.9% when thickness was 6 mm to 8 mm. Endometrial pattern was unrelated to pregnancy. Average endometrial thickness was decreased when hMG and CC were used in combination (7.9 mm) compared with hMG alone (9.4 mm). Endometrial thickness was negatively related to CC dose and positively related to the day of hCG administration by ANOVA., Conclusions: Endometrial thickness the day of hCG administration is prognostic of fecundity and continuing pregnancy in cycles of ovulation induction.

In order to assess the relationship between pre-ovulatory endometrial thickness and pattern and biochemical pregnancy, the pregnancy outcome was retrospectively analysed in 81 patients undergoing ovulation induction evaluated by vaginal ultrasound on the day of human chorionic gonadotrophin (HCG) administration or luteinizing hormone (LH) surge. Biochemical pregnancies occurred in 7/32 (21.9%) pregnancies when endometrial thickness was < 9 mm, compared to 0/49 when endometrial thickness was > or = 9 mm on the day of HCG administration or LH surge (P < 0.0025). Clinical abortions occurred in 5/32 (15.6%) pregnancies when endometrial thickness was 6-8 mm, compared to 6/49 (12.2%) when endometrial thickness was 6-8 mm (NS). Endometrial thickness was related to the cycle day of HCG or LH surge (r = 0.37, P < 0.001) but was unrelated to oestradiol level on the day of HCG administration or LH surge (r = 0.12). Biochemical pregnancies were related to endometrial pattern (r = -0.22, P = 0.02) but were unrelated to maternal age or previous abortions. Clinical abortions were related to age (r = 0.26, P = 0.01) and to previous abortion (r = 0.25, P = 0.013) but were unrelated to endometrial pattern. Neither biochemical pregnancy nor clinical abortion was related to oestradiol or LH levels on the day of HCG administration or LH surge. These findings suggest that the majority of biochemical pregnancies do not result from karyotypically abnormal embryos, as do clinical abortions.

The need for frequent injections and monitoring, the possibility of multiple gestations, and the higher cost compared to clomiphene citrate, prevents many clinicians from using human menopausal gonadotrophin (HMG) for ovulation induction. A sequential medication regimen, in which HMG is taken after clomiphene, overcomes these problems. We retrospectively compared per cycle fecundity and birth rates in 119 cycles of clomiphene-HMG, 524 cycles of clomiphene alone, 57 cycles of HMG alone, and 79 cycles of concurrent HMG and clomiphene in patients receiving intra-uterine insemination (IUI), who were free of endometriosis or tubal disease. Per cycle fecundity for clomiphene-HMG was 22% [95% confidence interval (CI) 12-34%], double that of clomiphene alone (11%) (95% CI 8-14%) (P < 0.01), and equal to HMG alone (18%) (95% CI 7-29%) or HMG and clomiphene together (19%) (95% CI 10-28%). The multiple birth rate for clomiphene-HMG (7/21) equalled that for HMG alone (3/12) and HMG and clomiphene together (3/8). The average number of ampoules of HMG required [follicle stimulating hormone (FSH) 75 mIU, luteinizing hormone (LH) 75 mIU] was decreased by 65% from 24.5 +/- 1.0 for HMG or HMG and clomiphene together to 8.6 +/- 0.3 for clomiphene-HMG (P < 0.001). Per cycle fecundity was identical when one, two or three ampoules of HMG per day were administered after clomiphene. We conclude that ovulation induction with sequential clomiphene-HMG results in fecundity double that of clomiphene alone and equal to HMG alone or concurrent with clomiphene, thereby reducing the requirement for HMG.

The incidence of differences in gestational sac diameter and crown-rump length, measured at the time of the first ultrasound, in which at least one gestational sac or crown-rump length could be visualized, were analysed retrospectively in 260 twin pregnancies in which one or both fetuses were delivered at term. The difference in gestational sac diameter averaged 1.2 +/- 0.1 mm for pregnancies which ended in twin births, compared to 2.0 +/- 0.3 mm when pregnancy ended in single births (P less than 0.02). The difference in crown-rump length averaged 2.4 +/- 0.6 mm for pregnancies which ended in a single birth, compared to 0.9 +/- 0.1 mm for twin births (P = 0.02). Disparities of greater than or equal to 3 mm in gestational sac diameter (P less than 0.05) or crown-rump length (P less than 0.001) were associated with an embryo loss rate greater than or equal to 50%. The disparity in gestational sac diameter (P less than 0.04) and crown-rump length (P less than 0.01) was smaller in pregnancies resulting from assisted reproductive technologies, compared with pregnancies resulting from coitus or insemination. Differences in gestational sac diameter and crown-rump length in early pregnancy were unrelated to differences in birth weight, length or sex.

We analyzed retrospectively the incidence of subchorionic fluid and embryonic death in 2116 consecutive patients evaluated with abdominal ultrasound and 783 patients evaluated with vaginal ultrasound. These women were examined during the first 12 postmenstrual weeks and had conceived as a result of infertility treatment. In addition, we analyzed the relationship of subchorionic bleeding to subchorionic fluid in 230 patients evaluated with color Doppler ultrasound and the relationship of subchorionic bleeding to clinical bleeding, precipitating factors, pregnancy outcome, and the karyotypes of abortuses. In single gestational sac pregnancies, subchorionic fluid was found equally often in women scanned with vaginal or color Doppler ultrasound, and less often with abdominal ultrasound (P less than .0001). Embryonic death was increased only in patients with large amounts of subchorionic fluid observed on abdominal ultrasound. Color Doppler ultrasound revealed subchorionic bleeding in 87 of 235 ultrasound scans (37%) and in 48 of 102 patients (47%) when subchorionic fluid was present. Subchorionic bleeding was associated with moderate or large amounts of subchorionic fluid (P = .041), with precipitating events (P less than .0001), and with clinical bleeding (P = .001). It was occult in ten of 48 patients (21%). Embryonic death occurred equally often in women with no fluid and in those with subchorionic fluid, with and without subchorionic bleeding. Abortuses were karyotypically abnormal in an equal proportion of cases with subchorionic bleeding, subchorionic fluid, and no fluid. These findings indicate that subchorionic fluid and subchorionic bleeding are common findings in early pregnancy and are not associated with embryonic death unless they are accompanied by clinical bleeding.

We retrospectively reviewed ultrasound findings in 539 infertility patients to evaluate the incidence of small gestational sac syndrome and its association with abortion, karyotype of the abortus, and known abortion factors. Small gestational sac syndrome (gestational sac diameter minus crown-rump length less than 5 mm) occurred in 1.9% of pregnancies scanned with vaginal ultrasound 37-65 days after the first day of the last menstrual period. The rate of fetal death was 80.0% when the gestational sac diameter-crown-rump length difference was less than 5 mm, 26.5% when the difference was 5-7.9 mm (P less than .002 compared with less than 5 mm), and 10.6% when the difference was 8 mm or more (P less than .0001 compared with less than 5 mm). Karyotypes were normal in all eight fetuses when the gestational sac diameter-crown-rump length difference was less than 5 mm (P less than .03). Small gestational sac syndrome was present before fetal death in 10.7% of all cases, and in 24% in which the karyotype was normal. Of the factors analyzed--maternal age, previous abortions, low hCG or progesterone levels, and use of ovulation induction medications--only maternal age was significantly different (P = .011) in patients with small sac syndrome. We conclude that small gestational sac syndrome is an infrequent but important complication of early pregnancy, which occurs more often in karyotypically normal than in abnormal fetuses.

Objective: To determine characteristics associated with pregnancy and multiple gestation after clomiphene citrate (CC)-intrauterine insemination (IUI)., Design: Prospective study of all patients undergoing CC-IUI between January 1, 1983 and December 31, 1989., Setting: Private fertility clinic., Patients: Eight hundred forty-nine patients undergoing 1,974 cycles of CC-IUI., Main Outcome Measures: Relationship between number and size of preovulatory follicles, age, additional infertility diagnosis, medication, and initial semen quality to fecundity, birth, and multiple gestation., Results: Uncorrected, per cycle fecundity was 7.2%. The number of follicles greater than or equal to 12 mm (r = 0.055, P less than 0.05) was and the number greater than or equal to 15, 18, and 21 mm was not correlated with fecundity. Endometriosis with (P = 0.013) or without (P less than 0.0005) tubal adhesions and tubal adhesions alone (P = 0.005), decreased fecundability by 50%. Initial semen quality did not affect fecundity, unless semen concentration was less than 5 x 10(6)/mL or motility was less than 20%. Multiple pregnancy was not associated with the dose of CC, use of human chorionic gonadotropin, or number of follicles., Conclusions: Multiple pregnancy was unrelated to follicle numbers or to CC dose. The highest birth rates after CC-IUI occurred when initial sperm concentration was greater than or equal to 5 x 10(6)/mL, motility was greater than or equal to 20%, and no endometriosis or adhesions were present.

The endometrial pattern and thickness was analysed prospectively on the day of administration of human chorionic gonadotrophin (HCG) in 200 in-vitro fertilization (IVF), gamete intra-Fallopian transfer (GIFT) and tubal embryo transfer (TET) cycles. Increasing maturity of the endometrial pattern was positively correlated with oestradiol levels (r = 0.20; P = 0.005), number of mature eggs (r = 0.13; P less than 0.05) and the number of top quality embryos (r = 0.40; P less than 0.001). The endometrial thickness was positively correlated with the number of follicles greater than or equal to 15 mm (r = 0.15; P less than 0.02) and the cycle day on which HCG was administered (r = 0.14; P less than 0.03). It was unaffected by the dose of human menopausal gonadotrophin and was negatively correlated with the use of clomiphene citrate (r = 0.40; P less than 0.001). Fecundity was increased for IVF when the endometrial thickness was greater than or equal to 9 mm (P less than 0.05) and for GIFT and TET when a Type C triple-line endometrial pattern was present (P less than 0.05). Biochemical pregnancies for the combined methods increased from 2.5% of all pregnancies when the endometrial thickness was 9-13 mm, to 27.8% when the thickness was less than 9 mm or greater than 13 mm (P less than 0.01). Biochemical pregnancies occurred in 67% of IVF pregnancies when the endometrial thickness was greater than or equal to 3 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Objective: To determine the characteristics associated with pregnancy and multiple gestation after human menopausal gonadotropin intrauterine insemination (hMG-IUI)., Design: Prospective study of all patients undergoing hMG-IUI between January 1, 1984 and December 31, 1989., Setting: University affiliated private clinic., Patients: Four hundred twenty-four infertility patients undergoing 779 cycles of hMG-IUI., Main Outcome Measures: The relationship between estradiol (E2), number and size of follicles, age, and initial semen quality on pregnancy and multiple gestations in hMG-IUI cycles., Results: The number of follicles greater than or equal to 12 mm was correlated with births and predicted all multiple births (r = 0.140, P less than 0.001). The corrected birth rate was 25.8% for age less than 35 and 14.0% for age greater than or equal to 35 when four or more follicles were greater than or equal to 12 mm. The uncorrected clinical pregnancy rate (PR) and birth rate were 12.8% and 10.5%, respectively. Decreased births were associated with tubal adhesions alone (P less than 0.03) or with endometriosis (P less than 0.002), more than four cycles of treatment (P = 0.01), initial sperm count less than 5 x 10(6) per mL (P less than 0.01), initial sperm motility less than 30% (P less than 0.002), and age greater than or equal to 35 (P less than 0.01). Estradiol was correlated with birth rate (r = 0.160, P less than 0.001), which increased from 3.6% when E2 was less than 500 pg/mL to 19.6% when E2 was greater than or equal to 2,500 pg/mL., Conclusions: The outcome of hMG-IUI is related to the number of follicles greater than or equal to 12 mm, to E2, and to age. Optimal PRs from hMG-IUI require mild ovarian hyperstimulation.

The live birth outcome when multiple gestational sacs were diagnosed at first trimester ultrasound was reviewed in 227 twin, 43 triplet and five quadruplet pregnancies. When two gestational sacs were present, the probability of delivering twins was 63% for maternal age less than 30 and 52% for maternal age greater than or equal to 30. With three gestational sacs, the probability of a triplet birth was 45% for maternal age less than 30 and 18% for maternal age greater than or equal to 30. When two viable embryos were present, the probability of a twin birth was 90% for maternal age less than 30 and 84% for maternal age greater than or equal to 30. With three viable embryos, the probability of a triplet birth was 90% for maternal age less than 30 and 44% for maternal age greater than or equal to 30. Two gestations resulting from ovulation induction with clomiphene citrate were more likely to result in twin delivery at term, compared to spontaneous twin gestations (P = 0.012). These findings may be useful in the treatment and management of patients when multiple gestations are diagnosed early in pregnancy.

Aspiration of spermatozoa from the caput region of the epididymis was performed, due to obstructive azoospermia. When all inseminated oocytes failed to fertilize in vitro, immotile spermatozoa were microinjected into the perivitelline space to achieve fertilization. Of six oocytes microinjected, one exhibited two normal pronuclei and two polar bodies and was subsequently transferred to a fallopian tube of the wife. One oocyte arrested at syngamy, while two additional oocytes cleaved to four cells each. The remaining two were damaged during microinjection. Although the patient did not conceive, this report provides evidence that (1) spermatozoal motility is not required for successful pronuclear formation when microinjection is performed, and such immotile sperm are not necessarily "dead," and (2) this further corroborates that caput epididymal spermatozoa can participate in the subzonal events of fertilization and that, in the human, exposure of spermatozoa to the distal epididymal milieu may not be a requisite to achieve fertilizing capacity.

The relationship between post-thaw motility and the percentage of sperm with intact acrosomes was evaluated in semen from 26 yearling Hereford or Angus bulls. A total of 409 samples was used, which consisted of 208 pooled first and second ejaculates, split and frozen in ampules and straws. All bulls passed a breeding soundness exam several weeks prior to the experiment. However, bulls were not subjected to any further selection for seminal quality, and all were of unknown fertility. In addition, all ejaculates from each bull were frozen without regard to seminal quality. Motility was assessed immediately after thawing, whereas acrosomal integrity was evaluated after 2 h of post-thaw incubation at 38 degrees C. The simple coefficient of correlation among bulls between motility and percentage of sperm with intact acrosomes was only .33. When variation in seminal quality among bulls was removed statistically, the corresponding coefficient of correlation within bulls was only .23. Under conditions of this experiment, post-thaw motility and acrosomal integrity constituted distinct, separate features of spermatozoal integrity that varied independently of each other.

In this study, GIFT resulted in a 44% pregnancy rate. When excess oocytes fertilized and developed to the blastocyst stage, the pregnancy rate was 78%. The continuing pregnancy rate was increased from 31% to 55% when sibling blastocysts developed.

Eight experiments were performed to validate an extraction technique for canine acrosin and to quantitate the acrosin activity of fresh and frozen-thawed spermatozoa. Acrosin activity from fresh spermatozoa differed amongst dogs and was influenced by the interval since previous ejaculation. Freezing and thawing spermatozoa induced a loss of acrosin activity that differed with the extender in which the spermatozoa were frozen. The assay of acrosin activity, in conjunction with motility estimates, provides a more complete evaluation of the efficacy of seminal extenders in attenuating freezing injury than do motility estimates alone.

Two experiments established the relationships among total scrotal width (TSW), daily spermatozoal production (DSP), daily spermatozoal output (DSO) and extragonadal spermatozoal reserves (EGR) of dogs ejaculated daily. In Experiment 1, 11 dogs (14 to 36 kg) were ejaculated daily for two 10-day periods and in Experiment 2, seven dogs (15 to 47 kg) were ejaculated daily for two 20-day periods. Approximately six daily ejaculations were required for stabilizing DSO. After the second period of daily ejaculations, dogs were castrated or killed and the testes were weighed and DSP and EGR were determined. In Experiments 1 and 2, DSP averaged 11.7 +/- 0.5 and 16.7 +/- 1.4 X 10(6) per gram of testicular parenchyma, respectively, or 369 and 594 X 10(6) per dog. DSP per gram of testicular parenchyma was not significantly correlated with parenchymal weight for the same testis in either experiment (r = 0.04 and 0.26). Mean (+/- SEM) EGR of dogs in Experiment 1 were 4024 +/- 368 X 10(6) and 4791 +/- 767 X 10(6) in Experiment 2. Approximately 63% of the EGR were contained in the caput and corpus epididymidis, 36% in the cauda epididymidis and 1% in the ductus deferens. DSO averaged 79 and 82% of DSP for the 2 groups of dogs. Based on combined data for all 18 dogs, TSW was correlated with testicular weight (r = 0.95; P less than 0.01), DSP (r = 0.82; P less than 0.01) and DSO (r = 0.75; P less than 0.01). Thus, measurement of TSW is a useful predictor of a dog's ability to produce and ejaculate spermatozoa.

An eleven-year review of treatment records of patients who became pregnant as a result of infertility treatment (n = 3692) was conducted. All records were examined to determine whether clomiphene citrate (CC) was used in the cycle of conception and whether or not an ectopic pregnancy occurred. Data were additionally analyzed for the incidence of ectopic pregnancy with and without assisted reproductive technology (ART). The incidence of ectopic pregnancy was similar between CC (3.4%) and non-CC (3.4%) treatment groups receiving non-ART treatment. For non-ART treatments, tubal disease and severe endometriosis resulted in an increase in ectopic pregnancies independent of CC use. The incidence of ectopic pregnancy in patients receiving CC + human menopausal gonadotropin (hMG) for in vitro fertilization (5.4%) and gamete intrafallopian transfer (3.1%) was similar compared to ART treatments with hMG alone. The incidence of ectopic pregnancy was more closely associated with infertility diagnosis rather than CC use.

Forty-four percent of started GIFT cycles were cancelled. Insemination and intercourse in the cancelled cycles yield a 23% and 10% pregnancy rate, respectively.

This report describes both gamete intrafallopian transfer (GIFT) and pronuclear-stage transfer (PROST) of donated oocytes to patients with premature ovarian failure (POF), using micronized oral progesterone (P4) and low-dose micronized estradiol (E2) for endometrial preparation and maintenance. Patient A, with POF of 15 years' duration, received four donated oocytes for GIFT and subsequently delivered a normal, term, female infant. Patient B was diagnosed as POF 3 years ago. She received four donated oocytes, which were subsequently fertilized in vitro with husband's sperm. The following day, four pronuclear-stage embryos were transferred to her fallopian tubes. She recently delivered twin, healthy female infants. These procedures, along with exogenous hormonal development of the endometrium, provide a simplified means to establish and maintain pregnancy in POF patients. Both patients were maintained on low-dose micronized E2 prior to their procedure, Patient A on 3 mg E2 per day cyclically and Patient B on 0.5 mg E2 continuously. Micronized oral P4 was used to maintain pregnancy.

Twenty-six Hereford or Angus bulls of breeding age were used to determine whether the anthelmintic albendazole influenced weights of reproductive organs, spermatozoal production, spermatozoal output, quality of freshly ejaculated or frozen semen, serum testosterone values, or libido. Values for most of these measurements in 12 bulls treated with a single oral dose (22.5 mg of albendazole/kg of body weight) were not different from those for 14 nontreated controls, and the few differences that were observed appeared to be spurious and generally were not significant (P less than 0.05) when data were adjusted for pretreatment differences among treated and control bulls. The treatment did not alter reproductive function of the bulls.

Experiments were conducted to evaluate two extenders (egg-yolk Tris and egg-yolk lactose), varying concentrations of two cryopreservatives (glycerol and dimethyl sulfoxide), and rates for cooling to 5 degrees C, cooling from 5 to -100 degrees C, and warming for canine spermatozoa packaged in 0.5-ml French straws. At optimal concentrations of glycerol, egg-yolk Tris extender was superior to egg-yolk lactose in preserving spermatozoal motility. Addition of dimethyl sulfoxide, alone or in combination with glycerol in either extender, was not beneficial to spermatozoal survival after thawing. Canine spermatozoa withstood a range of cooling and equilibration times with no detrimental effect on spermatozoal motility prior to freezing. However, there were differences in spermatozoal motility immediately after thawing; these differences were variable, resulting in a cooling time by equilibration time interaction. Spermatozoal motility after thawing was best preserved by freezing in egg-yolk Tris extender containing 2-4% glycerol, using a moderate rate of cooling from 5 to -100 degrees C (-5 degrees C/min from 5 to -15 degrees C, then -20 degrees C/min from -15 to -100 degrees C). Three of 12 bitches inseminated intravaginally with semen frozen using this protocol became pregnant.

Stallion semen was collected, using artificial vaginas at 44 to 46, 48 to 50, and 52 to 54 C, to study the effects of temperature on seminal quality and sexual behavior. The temperature of the artificial vagina had no significant effect on motility, gel volume, gel-free seminal volume, total seminal volume, pH, number of mounts per ejaculate, total time to ejaculation, or seminal temperature. Spermatozoa were collected, then exposed to water-bath temperatures of 38, 45, 49, or 53 C for 1 minute. Mean motility was similar after exposure to temperatures of 38 or 45 C, but exposure to temperatures of 49 or 53 C resulted in a significant decrease (P < 0.05) in spermatozoal motility with each increase in temperature. Thus, it was concluded that spermatozoa exposed to temperatures greater than 45 C may be irreversibly damaged.