Scrotal temperature reflects intratesticular temperature and is lowered by shaving

Reference value of testicular temperature measured by finite element analysis after first staged inguinal orchidopexy in children with abdominal testis and short spermatic cord

PURPOSE

This study aims to build a 3D reconstruction computed simulation model and to establish a regression equation for detecting the testis's temperature by its location after first staged open orchidopexy in children with abdominal undescended testis (UDT) and short spermatic cords.

METHODS

In this cross-sectional study, we enrolled 31 children with abdominal UDT and short spermatic cords who underwent first staged orchiopexy between 2017 and 2020. Using ultrasonography to obtain the testis's location distance from the skin surface (X1), external iliac vessel (X2), and internal inguinal ring (X3), we input the data into a 3D reconstruction computed simulation along with COMSOL to calculate the testicular temperature. We also used multivariate regression to establish the testicular temperature regression equation from the gathered data.

RESULT

The mean age of the participants was 4.47 ± 1.21 years. The mean size of the operated testis was 0.39 ± 0.13 cc. The mean distance of the testis from X1, X2, and X3 was 3.27 ± 1.25 mm, 21.06 ± 6.42 mm, and 27.19 ± 10.09 mm, respectively. The testicular temperature regression equation derived from testis location was calculated by the formula: 34.57 + 0.0236 X12 - 0.0105 X2 - 0.0018 X3. The concordance for testis temperature calculated via the computational method and regression equation was 83%.

CONCLUSIONS

The current study provided a reference value for the testicular temperature of children with abdominal UDT and short spermatic cords after the first stage of orchiopexy. A testicular temperature regression equation can be established based on the testis location, which will provide relevant information for the testicular development assessment, disease diagnosis, and follow-up, and possibly determination of the time of the second stage of orchiopexy.

Hernioplasty and testicular perfusion

Open and laparoscopic tension-free techniques of hernia repair using synthetic meshes are a well-accepted practice with an excellent patient comfort and a low recurrence rate. It is well known that, direct contact of the mesh to the vessels in the inguinal canal and perimesh fibrosis may have a negative impact on testicular flow. Whether different operative techniques or mesh materials used have an effect on the integrity of the testicle, the influence of the resulting fibrosis on testicular perfusion, and spermatic cord structures is still unclear. Our objective is to review whether there is an association between inguinal hernia and hernia repair techniques, pitfalls of various manipulations and also specific applications on spermatic cord structures and testicular perfusion in view of the literature. Most of the clinical and experimental studies result support the idea that inguinal mesh application for hernioplasty is still a safe procedure in patients. Testicular blood flow may be influenced during open and laparoscopic inguinal hernia surgery. But, so far, there is no evidence for a significant impairment of cord structures after open or laparoscopic hernia repair using tension free techniques. It is clear that fine surgical dissection and reconstruction, doing respect for anatomy and using proper prosthetic material could be obtain the best results. Whether changes in flow parameters remain in the late postoperative period, and whether they have an impact on complications should be evaluated in further clinical and experimental studies.

Influence of moderate cycling on scrotal temperature

Testicular temperature highly correlates with scrotal temperature. It has been postulated that cycling is associated with increased scrotal temperatures with time and consecutively with impaired semen quality. The aim of this study was to evaluate the influence of moderate cycling on scrotal temperature during highly standardized conditions in an experimental lab. A total of 25 volunteers without a history of infertility and normal andrological examination were included for scrotal temperature evaluation. Scrotal temperatures were measured every minute with a portable data recorder connected with two thermistor temperature sensors, which were attached on either side of the scrotum. A further thermistor sensor was attached on the central surface of the bicycle saddle. Ambient temperature in the study room was adjusted to 22 degrees C throughout the whole experiment. All volunteers started the experiment at the same daytime. Clothing of the volunteers consisted of standardized cotton wool trousers and shirts fitting to body size. After acclimatization to the study room in a sitting posture, each volunteer cycled on an exercise cycle for 60 min with a power of 25 Watt representing a speed of 25.45 km/h respectively. The saddle surface temperature reached in the median 35.59 degrees C after 60 min cycling. Median values of scrotal temperatures increased from 35.75 degrees C at the beginning to 35.82 degrees C after 60 min for the left side and from 35.50 to 35.59 degrees C for the right side. No correlation between cycling duration and scrotal temperatures could be found using multivariate anova for repeated measurements. However, scrotal temperatures during cycling were significantly lower (p < 0.001) compared with the last 10 min in sitting posture before starting cycling with a difference of 1.31 degrees C for the left and 1.46 degrees C for the right side. The present study suggests that moderate cycling under standardized conditions with a power of 25 Watt is not a major genital heat stress factor.

Improvement of semen quality by nocturnal scrotal cooling in oligozoospermic men with a history of testicular maldescent

For infertile men with a history of testicular maldescent only few therapeutic options exist beside assisted reproduction. The aim of our study was to evaluate the influence of nocturnal scrotal cooling on semen quality in such patients presenting with oligozoospermia. Twenty infertile men with a history of testicular maldescent and oligozoospermia were included for nocturnal scrotal cooling over 12 weeks for every night. To increase nocturnal periscrotal air circulation we used a membrane pump connected via plastic tubes to receptacles placed in both groins. Semen analysis was performed at the beginning of the cooling period and at weeks 4, 8 and 12. Another 20 infertile patients with a history of testicular maldescent and oligozoospermia were followed without specific treatment and served as a retrospectively built control group. Scrotal cooling at night by means of a perigenital air stream resulted in a scrotal temperature drop by 0.8 degrees C (median). A significant increase in sperm concentration and total sperm count was achieved by nocturnal cooling after 8 weeks (p < 0.01; p < 0.05; respectively) and 12 weeks (p < 0.01; p < 0.01; respectively). The improvement of sperm motility and sperm morphology was statistically insignificant. The present study suggests nocturnal scrotal cooling as a therapeutic option to improve semen quality. In a further controlled prospective study the influence on pregnancy rates should be evaluated.

Increase in scrotal temperature in laptop computer users

BACKGROUND

Scrotal hyperthermia has been identified as a risk factor for male infertility. Laptop computers (LC) have become part of a contemporary lifestyle and have gained popularity among the younger population of reproductive age. LC are known to reach high internal operating temperatures. We evaluated the thermal effect of LC on the scrotum.

METHODS

Right and left scrotal temperature (ScT) was measured in 29 healthy volunteers in two separate 60 min sessions. ScT was recorded from thermocouples on a digital datalogger every 3 min with the working LC in a laptop position and in the same sitting position with approximated thighs without LC.

RESULTS

ScT increased significantly on the right and left side in the group with working LC (2.8 degrees C and 2.6 degrees C, respectively; P<0001) and without LC (2.1 degrees C, P<0.0001). However, ScT elevation with working LC was significantly higher (P<0.0001).

CONCLUSIONS

Working LC in a laptop position causes significant ScT elevation as a result of heat exposure and posture-related effects. Long-term exposure to LC-related repetitive transient scrotal hyperthermia is a modern lifestyle feature that may have a negative impact upon spermatogenesis, specifically in teenage boys and young men. Further studies of such thermal effects on male reproductive health are warranted.

Influence of the type of undertrousers and physical activity on scrotal temperature

BACKGROUND

Testicular temperature correlates highly with scrotal temperature. The aim of this study was to evaluate the influence of the type of undertrousers on scrotal temperature during standardized periods of sitting and walking.

METHODS

Fifty volunteers without a history of infertility and normal andrological examination were included for scrotal temperature evaluation. Temperatures were measured every minute with a portable data recorder connected with two thermistor temperature sensors, which were attached on either side of the scrotum. Ambient temperature in the study room was adjusted to 20 degrees C throughout the whole experiment. All volunteers started the experiment at the same time of day. Clothing of the volunteers consisted of standardized cotton wool trousers and shirts fitting to body size. Each volunteer performed six periods of 45 min, either walking on a treadmill (3.0 km/h) or sitting, and wearing in a standardized and randomized manner either tight, loose fitting or no undertrousers respectively.

RESULTS

The following interactions were demonstrated by means of multivariate analysis of variance for repeated measurements: scrotal temperatures were significantly higher for tight versus loose fitting versus absent undertrousers. Furthermore, significantly lower scrotal temperatures were identified for walking versus sitting as well as for the right versus the left scrotal side.

CONCLUSIONS

The present study suggests that wearing tight fitting undertrousers is associated with higher scrotal and consequently testicular temperatures than wearing loose fitting undertrousers or none.

Relationship between sleeping posture and fluctuations in nocturnal scrotal temperature

Elevated testicular temperatures are a potential risk factor for impaired spermatogenesis and reduced semen quality. The development of portable devices for the measurement of scrotal temperatures closely correlating with testicular temperature offered the opportunity to identify periods with high scrotal temperatures during daily life. Notably, sleeping periods covering approximately 1/3 of the day are associated with increased scrotal temperatures to around 36 degrees C. Combining infrared video taping with scrotal temperature profiling, our study clarified that sudden drops of scrotal temperature during sleep are the consequence of changes of posture. Nocturnal scrotal temperatures were significantly higher during sleeping on the side compared with periods lying on the back (+0.65 degrees C, right scrotum, P<0.001; +0.54 degrees C, left scrotum, P<0.001). Median values of nocturnal scrotal temperatures did not significantly differ between 11 volunteers with normozoospermia and 22 men with oligozoospermia. Furthermore, continued scrotal temperature profiling during the following day only showed significantly higher values among men with oligozoospermia than among volunteers for the left scrotal side (+0.70 degrees C, P<0.05), but not for the right scrotal side (+0.39 degrees C, P>0.05). This difference could not be attributed to higher scrotal temperature values during periods with physical inactivity (median in both groups above 36 degrees C) but the duration of physical inactivity in men with oligozoospermia was 50% longer than in volunteers. Thus, in the setting of the present study it was not possible to demonstrate a close correlation between scrotal temperature and semen quality.

Genital heat stress in men of barren couples: a prospective evaluation by means of a questionnaire

Exposure to genital heat stress among men of barren couples was evaluated in a prospective study. Five hundred and forty-two consecutive patients referred for andrological examination were asked to complete a specific questionnaire at their first visit. For 449 patients who answered all questions, the individual score values could be calculated by scoring each answer with points. Patients with 'idiopathic' oligoasthenoteratozoospermia had significantly higher score values when compared with men showing normozoospermia (P < 0.01), 'symptomatic' oligoasthenoteratozoospermia as a result of defined andrological disorders (P < 0.01), cryptozoospermia (P < 0.01) or other pathological semen profiles (P < 0.05). These data support the hypothesis that patients with 'idiopathic' oligoasthenoteratozoospermia are more exposed to genital heat stress than normozoospermic men. Moreover, in patients with a varicocele impairment semen quality was associated with significantly higher score values compared with the subgroup of men with normal semen profiles (P < 0.05). In contrast, the score values did not significantly differ between equivalent subgroups of men with a history of a retractile testis. Our observations indicate that the questionnaire used in the present study allows an integrative assessment of genital heat stress, which is superior to single factor analysis. Notably, the group of men with 'idiopathic' oligoasthenoteratozoospermia showed the highest mean score values for 10 of the 18 questions compared with the other groups. Prolonged sitting in a vehicle represented the only single factor with significantly different score values in patients with 'idiopathic' oligoasthenoteratozoospermia and those with normozoospermia (P < 0.05).

The relation between daily activities and scrotal temperature

Normal sperm production depends on a testicular temperature below body temperature, but the thermogenic effects of daily life activities are not well known. We described the association between scrotal temperature and daily activities in 101 males using a non-invasive method for measuring scrotal temperature. A thermistor was attached to the underwear and the temperature of the scrotal skin was logged by a portable device every 5 min for 24h. Participants reported sedentary position and activities at work and during spare time in a questionnaire. Scrotal temperature was strongly correlated with sedentary work position with a dose-effect association (<1 h sedentary: 33.1 degrees C, >6 h sedentary: 34.7 degrees C, median values). The variation in sedentary work accounted for 31.5% of the variation in median temperature during the entire 24h. Sedentary position during spare time did not correlate with scrotal temperature. Median temperature at night was 1.2 degrees C higher than during the daytime. No effect was found for size or reported tightness of the underwear. In a model experiment, the deviance between testicular and scrotal temperature was estimated as maximally 0.1-0.6 degrees C, depending on the type of activity. Measuring scrotal temperature provides a valid estimate of testicular temperature and is feasible in large cohorts. We conclude that work position is an important determinant of testicular temperature.

Scrotal temperature is increased in disposable plastic lined nappies

OBJECTIVES

Male reproductive health has deteriorated in recent decades. It is proposed that increased testicular temperature in early childhood, due to the use of modern disposable plastic lined nappies (diapers), could be an important factor contributing to this decline.

STUDY DESIGN

Scrotal skin temperature was measured non-invasively in 48 healthy children aged 0-55 months (three age groups) for two 24 hour periods in randomised order (either cotton or disposable plastic lined nappies) using a portable, miniature recorder.

RESULTS

Mean 24 hour scrotal temperature (2880 measurements) was significantly higher in all age groups during the periods of plastic nappy use than with cotton nappies (p < 0.001). The rectoscrotal temperature difference was significantly higher with cotton than with plastic nappy use (p < 0.01).

CONCLUSIONS

Scrotal hypothermia is an important factor for normal spermatogenesis. This study shows that scrotal temperature, which closely reflects testicular temperature, is increased in boys wearing disposable plastic lined nappies. The physiological testicular cooling mechanism is blunted and often completely abolished during plastic nappy use. The present results establish the basis for further research on the impact of increased testicular temperature in infancy on later spermatogenesis.

Diurnal scrotal skin temperature and semen quality. The Danish First Pregnancy Planner Study Team

It is well established that heat is associated with reduced sperm production, but the role of physiological variation in temperature has never been scrutinized in humans. We studied diurnal scrotal temperature and markers of male fertility in a population of couples planning their first pregnancy. Sixty men from a cohort of couples who were planning their first pregnancy were included and scrotal skin temperature was monitored during 3 days using a portable data recorder. Working hours and working postures were recorded daily in a questionnaire. Each man provided a fresh semen sample and the couples were followed for six menstrual cycles or until a clinical pregnancy was recognized. The median value of scrotal skin temperature was 33.3 degrees C in the daytime and 34.8 degrees C at night. In periods of sedentary work, the median temperature was on average 0.7 degrees C higher (SE=0.2 degrees C). In addition, scrotal temperature was higher in the daytime, in summer, and in leisure time compared with working hours. Median sperm concentration among men with more than 75% of their daytime readings above 35 degrees C was 33.4 x 10(6)/mL, compared with 91.8 x 10(6)/mL for men with less than half of their readings above 35 degrees C (difference 58.4; 95% CI: 25.9-77.8 x 10(6)/mL). It is concluded that a sedentary position is a significant source of increased scrotal skin temperature, and even moderate and physiological elevation in scrotal skin temperature is associated with a substantially reduced sperm concentration. Sedentary work should be considered as an important potential confounder for reduced sperm count in epidemiological research.

Radiofrequency energy-induced heating during MR procedures: a review

During an MR procedure, most of the transmitted RF power is transformed into heat within the patient's tissue as a result of resistive losses. Not surprisingly, the primary bioeffects associated with the RF radiation used for MR procedures are directly related to the thermogenic qualities of this electromagnetic field. This review article discusses the characteristics of RF energy-induced heating associated with MR procedures, with an emphasis on thermal and other physiologic responses observed in human subjects.

Increase in scrotal temperature in car drivers

Several recent studies have reported a gradual decline in sperm production in men. Endocrine disrupters as well as lifestyle have been suggested as risk factors. One lifestyle factor that may affect human fertility is driving a vehicle for a prolonged period. Several authors have suggested that driving position may increase the scrotal temperature. In order to validate this hypothesis we conducted continuous monitoring of scrotal temperature in real conditions, i.e. in men driving a car for a prolonged period. Nine volunteer men were asked to walk outside for 40 min and then to drive a car for 160 min. Scrotal temperatures were measured from thermocouples and values recorded every 2 min on a portable data recorder. Scrotal temperature increased significantly (P < 0.0001) in driving posture after 2 h of driving, reaching a value 1.7-2.2 degrees C higher than that recorded while walking. This link between driving position and increased scrotal temperature indicates a potential exposure of male reproductive function to lifestyle factors.

Reduction in testicular temperature after varicocelectomy in infertile men

OBJECTIVES

To study the effects of varicocelectomy on testicular temperature.

METHODS

Testicular skin surface temperature was directly measured with an electronic thermometer calibrated to 0.01 degree C in 119 men before and after microsurgical varicocelectomy and in 45 control patients without varicocele.

RESULTS

Testicular temperatures in men with varicocele were elevated preoperatively (right side [R]: 34.00 +/- 0.91 degrees C/left side [L]: 34.37 +/- 0.87 degrees C unilateral; R: 34.07 +/- 0.83 degrees C/L: 34.34 +/- 0.85 degrees C bilateral) relative to control patients (R: 33.04 +/- 2.47 degrees C/L: 32.86 +/- 2.52 degrees C) (P < 0.01). Postoperative temperatures were unchanged in the control patients. Testicular temperatures decreased after both bilateral and unilateral varicocelectomy (R: 33.03 +/- 0.85 degrees C/L: 32.84 +/- 1.0 degrees C unilateral; R: 33.27 +/- 1.0 degrees C/L: 33.54 +/- 1.2 degrees C bilateral) to levels nearly identical to those of control patients (P < 0.001).

CONCLUSIONS

Testicular temperatures were elevated bilaterally in men with both unilateral and bilateral varicoceles. Both unilateral and bilateral microsurgical varicocelectomy results in a bilateral decrease in testicular temperature. These results support the hypothesis that a defect in testicular thermoregulation contributes to the pathophysiology of varicocele and demonstrate, for the first time in humans, the efficacy of varicocelectomy in restoring normal testicular temperatures.

Diurnal variations in scrotal temperature of normal men and patients with varicocele before and after treatment

Scrotal temperature was monitored using a portable data recorder for periods of 24 h in six normal volunteers and 48 infertile patients with unilateral varicocele while subjects pursued their regular daily activities. Temperatures during sleep (TS) were generally higher than daytime values (TD), probably as a consequence of thermal insulation in bed. These diurnal variations were found to be less pronounced in the infertile patients than in volunteers (TS - TD = 0.29 degrees C +/- 0.06 degrees C vs 0.88 degrees C +/- 0.12 degrees C; P < 0.01). Moreover, scrotal temperatures at night of patients and volunteers were indistinguishable statistically, but were different during daytime hours. After successful ligation or embolization of the spermatic-vein in 16 patients, no change in scrotal temperature was observed. Although sperm counts were higher after treatment, this difference was not significant (67.4 +/- 17.2 x 10(6) vs 105.8 +/- 25.5 x 10(6); P > 0.05). The data support the view that varicocele-related damage to the testis results from a lack of adequate cooling, and that treatment does not normalize the temperature pattern.

The significance of elevated scrotal temperature in an adolescent with a varicocele

Simultaneous measurements of left and right scrotal, and axillary skin temperatures were recorded in 58 consecutive adolescents (mean age 14.4 years) with a grade II-III left sided varicocele, and nine control adolescents without genital pathology (mean age 15.7 years). Left and right testicular volumes were determined in both groups. The adolescents with a varicocele had a significant bilateral elevation of the scrotal temperatures compared to the control subjects. This relative hyperthermia was present in both supine and standing positions. The mean left scrotal temperature of varicocele patients was significantly higher in the standing position than in the supine position, which may reflect the dependent venous filling of the varicocele. Those varicocele patients who maintained a left scrotal temperature at least 1.4 degrees C cooler than axillary did not have significant left testicular volume loss, whereas those whose left temperature was approximately equal to axillary did have significant growth retardation of the left testis. Following successful varicocele surgery, left scrotal temperatures were significantly cooler, and statistically indistinguishable from controls. The left testicular volumes were also significantly improved with respect to corresponding right testicular volumes. These observations suggest that adolescents with a moderate to large left varicocele have a significant bilateral loss of testicular thermoregulation. In those individuals with a significantly warmer left hemiscrotum, there is a definite increased potential for left testicular volume loss. Varicocele surgery can reverse this process.

Depressed DNA synthesis in vitro by early prepubertal undescended human testis

To study the spermatogenic potential of the early prepubertal inguinal testis and the effect of temperature on spermatogenesis, the levels of incorporation of 3H-thymidine and 14C-uridine into the testicular tissue were studied at 31 degrees C and 37 degrees C in vitro and compared with those of scrotal (descended) testis. 3H-thymidine incorporation into the inguinal testicular tissue at 31 degrees C, which is close to normal testicular temperature, was significantly lower than that of the scrotal testis. There was no significant differences in 14C-uridine incorporation between inguinal and scrotal testis at that temperature. At 37 degrees C, which is close to normal body temperature, 3H-thymidine and 14C-uridine incorporation into the tissues of inguinal and scrotal testes was significantly higher than at 31 degrees C. It would appear that DNA synthesis of the inguinal testis is lower than that of the scrotal testis at 31 degrees C, and higher temperature, at least for a short while, did not contribute to the impairment of spermatogenic potential in early prepubertal inguinal testis.

A portable digital data recorder for long-term monitoring of scrotal temperatures

The application of a new, miniaturized portable digital data recorder "Thermoport" (Institute for Reproductive Medicine, Münster, West Germany) for continuous determination of scrotal temperatures revealed great variations of scrotal temperature during 24 hours in normal men. Maximum temperatures approached body core temperatures. Mean scrotal temperatures of 10 normal men rose during sauna from 32.72 +/- 0.23 degrees C to 37.53 +/- 0.38 degrees C. During treadmill running, scrotal temperatures increased by more than 2.5 degrees C. Minimal scrotal temperatures were increased in some men with varicocele compared with normal fertile men indicating impaired cooling mechanisms. The continuous temperature measurements facilitate assessment of temperature dynamics. The miniaturized design of the Thermoport makes it suitable for routine use in outpatients of infertility clinics, in occupational medicine for evaluation of heat hazards, and for investigations of body temperatures under various experimental conditions.

Scrotal temperature and semen quality in men with and without varicocele

The exact role of varicocele in human male infertility remains controversial. Fifty-five male partners of infertile couples randomly selected and 17 fertile semen donors were evaluated for semen quality, scrotal temperature, and presence of varicocele using clinical palpation and Doppler ultrasound. The incidence of varicocele was 42% in male partners of infertile couples and 41% in fertile semen donors. Left scrotal temperature was significantly (p less than .001) higher in infertile males with varicocele as compared to all groups. No significant differences were observed in the percentage of morphologically normal sperm in semen of males with and without varicocele. However, the incidence of tapered, elongated, and immature sperm was significantly higher in the infertile patient population with a varicocele. Measurement of scrotal temperature and assessment of sperm morphology may be used as predictors of the presence and deleterious effect of varicocele.

Testicular macromolecular synthesis in men with varicocele

The synthesis of DNA, RNA, and protein by varicocele testes with spermatogenic dysfunction was studied by examination of the levels of incorporation of [3H]thymidine, [14C]uridine, and [14C]leucine into the testicular tissue at 31 degrees C in vitro. The results suggest that DNA synthesis by the testis with moderate tubular damage is impaired whereas synthesis of RNA and protein is not. The cell regenerative ability of the testis with moderate tubular damage may be poor in spite of the preservation of testicular cell RNA and protein synthesis.

Elevation of intratesticular and scrotal skin surface temperature in men with varicocele

A possible mechanism of varicocele-induced infertility is believed to be elevation of testicular temperature. Sensitive needle thermistors were used to measure directly intratesticular and bilateral scrotal surface temperatures simultaneously in anesthetized infertile men with varicocele and control subjects. We found that intratesticular temperature is elevated significantly in humans with varicocele. In addition, we have shown that scrotal skin surface temperature is elevated in men with varicocele. Furthermore, we demonstrate that unilateral varicocele is associated with bilateral elevation of scrotal surface temperature. These findings confirm the results of animal studies revealing elevation of intratesticular temperature associated with varicocele and suggest bilateral elevation in unilateral varicocele.

Impaired DNA synthesis by early pubertal cryptorchid testis in vitro

To study the spermatogenic potential of the early pubertal cryptorchid testis, testicular DNA synthesis was examined in vitro. DNA synthesis by early pubertal cryptorchid testis was inhibited and lost its normal temperature sensitivity. The spermatogenic potential of the cryptorchid testis may be impaired as early as puberty.

DNA and RNA synthesis by postpubertal undescended testis in vitro

To study the spermatogenic potential of postpubertal undescended testis, the 3H-thymidine and 14C-uridine incorporations into normally descended and inguinal undescended testes were examined. The results suggest that DNA synthesis by the inguinal undescended testis is remarkably inhibited but, on the contrary, RNA synthesis is not. The cell-proliferative ability of postpubertal undescended testis may be impaired in spite of the retention of cell viability in the testis.

Influence of occupation and living habits on semen quality in men (scrotal insulation and semen quality)

Fifty-six males from infertile couples were categorised into two different groups and their semen quality examined. Patients in which there was no evidence of interference with normal testicular thermoregulation either during the day or the night were classified as 'cool workers' and 'cool sleepers' (Group I, n = 26). In the other group (II), 'warm workers'/'warm sleepers' (n = 30), there was evidence for scrotal insulation. The number of good moving spermatozoa per ejaculate as well as this number per ml was greater in 'cool workers'/'cool sleepers' than in 'warm workers'/'warm sleepers' (p less than 0.001). These results emphasize the need for comprehensive patient history when evaluating infertility problems. Similarly, living habits may play a role in human male infertility and treatment.

Optimal temperature for synthesis of DNA, RNA, and protein by human testis in vitro

To determine the optimal temperature for DNA, RNA, and protein syntheses in the human testis, the levels of incorporation of 3H-thymidine, 14C-uridine, and 14C-leucine into testicular tissue were studied at 28 degrees C, 31 degrees C, 34 degrees C, and 37 degrees C in vitro. The results suggest that the DNA synthesis is at a maximum at 31 degrees C and shows delicate temperature sensitivity, whereas the RNA and protein syntheses are at a maximum at 34 degrees C or 37 degrees C and are temperature-dependent. It is concluded that the temperature sensitivity of DNA synthesis may be one of the primary causes of delicate thermal inhibition of human spermatogenesis.

Association of scrotal hyperthermia with impaired spermatogenesis in infertile men

Scrotal temperatures, testicular volumes, and sperm characteristics were studied in 150 infertile, nonazoospermic men and in 37 fertile men, used as a control group. The mean scrotal temperature values of the infertile men were significantly greater than those observed in the fertile men (+0.4 degrees C for the right; +0.5 degrees C for the left). In the infertile men, it was found that the higher the scrotal temperature, the more alterated the sperm characteristics. The only clinical element that seemed to be linked to the existence of scrotal hyperthermia in the infertile men was testicular hypotrophy. Although the scrotal temperatures of the infertile men with varicocele were significantly higher than those of the fertile men, they did not significantly differ from those of the infertile men without varicocele. No other specific pathologic factor, infectious or surgical urogenital history was found to be responsible for the scrotal hyperthermia observed in the infertile men.

Temperature sensitivity of human spermatogonia and spermatocytes in vitro

To study the effect of temperature on human spermatogenesis, both the number and DNA synthesis of germ cells were investigated in tissue fragments of human testes cultured for 22 h at 31 degrees C and 37 degrees C. The number of differentiated germ cells such as spermatids and spermatozoa cultured at 37 degrees C was significantly smaller than that cultured at 31 degrees C. The number of spermatogonia and resting primary spermatocytes was not significantly different between these two temperatures, but the functional ability of DNA synthesis in these cells was significantly lower at 37 degrees C than at 31 degrees C. It seems that in normal body temperature (37 degrees C) differentiated germ cells such as spermatids and spermatozoa are fragile and the DNA synthesis of spermatogonia and resting primary spermatocytes is retarded.