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The Structural Changes in the Testicle of the Dog when it is Replaced within the Abdominal Cavity
... Body temperature regulation is crucial to ensure the optimal testicular function (Setchell, 1993). The idea that hyperthermia is harmful for functioning of scrotal testes, comes from the observation that the failure of testes to descend into the scrotal cavity caused impairment in sperm production (Jung et al., 2005b;Griffiths, 1893;Foldesy and Bedford, 1982;Jung and Schuppe, 2007). In most of mammals, including rat, the site of testes in the scrotum exterior to the body cavity helps to maintain a lesser testes temperature compared to rest of the body (2°C less than body temperature) (Harrison and Weiner, 1949). ...
Ability of red grape juice (RGJ), a known antioxidant, on testis of adult Wister rat to protect from oxidative stress induced damages by heat stress has been investigated in this study. Heat stress was induced maintaining body and testicular temperature at 43°C for 30 min/day for 15 days using a hyperthermia induction chamber. Four groups of rats (n=6 per group) comprising of Group-I (control) –kept at 32 °C, Group-II –exposed to heat stress alone, Group-III received RGJ (0.8 ml/rat/day) alone and Group-IV –exposed to heat stress and received RGJ at same dose. Analysis of blood and testicular tissue exhibited significant reduction in serum testosterone, testicular superoxide dismutase, testicular catalase and testicular glutathione (all P<0.001); whereas, significant rise in the level of serum corticosteroid, testicular lipid peroxidase and the apoptotic enzyme caspase-3 of testis (all P<0.001) were observed along with substantial increase in testicular Hsp72 and Hsf-1, and decrease in 17β-HSD3 were noted in heat stressed rats compared to controls. In Group-IV rats, RGJ administration could restore these parameters to normal levels. The signs of retention were clear in Group-IV rats and found to be significantly different as compared to that of the Group-II rats. In testicular histology of rats exposed to heat stress alone revealed remarkable germ cell degeneration and tubular deformations which were prevented by RGJ treatment (Group-IV). The reduced number of sperm level in Group-II also restored in RGJ treatment (Group-IV). The above results indicate that consumption of RGJ may substantially protect testis from heat stress induce dysfunctions.
... It was well known that surgical induction of cryptorchidism in experimental animals causes the rapid degeneration of germ cell in testes and disrupts spermatogenesis [15,16]. By contrast, sertoli cells, which are essential for spermatogenesis, appear to be normal when exposed to the higher abdominal temperatures [17]. ...
Transplantation of spermatogonial stem cells (SSCs) in experimental animal models has been used to study germ line stem cell biology and to produce transgenic animals. The species-specific recipient model preparation is important for the characterization of SSCs and the production of offspring. Here, we investigated the effects of surgically induced cryptorchidism in dog as a new recipient model for spermatogonial stem cell transplantation. Artificially unilateral or bilateral cryptorchidism was induced in ten mature male dogs by surgically returning the testis and epididymis to the abdominal cavity. The testes and epididymides were collected every week after the induction of artificial cryptorchidism (surgery) for one month. To determine the effect of surgical cryptorchidism, the seminiferous tubule diameter was measured and immunohistochemistry using PGP9.5 and GATA4 antibodies was analyzed. The diameters of the seminiferous tubules of abdominal testes were significantly reduced compared to those of the scrotal testes. Immunohistochemistry results showed that PGP9.5 positive undifferentiated spermatogonia were significantly reduced after surgical cryptorchidism induction, but there were no significant changes in GATA-4 positive sertoli cells. To evaluate the testis function recovery rate, orchiopexy was performed on two dogs after 30 days of bilateral cryptorchidism. In the orchiopexy group, SCP3 positive spermatocytes were detected, and spermatogenesis was recovered 8 weeks after orchiopexy. In this study, we provided optimum experimental conditions and time for surgical preparation of a recipient canine model for SSC transplantation. Additionally, our data will contribute to recipient preparation by using surgically induced cryptorchidism in non-rodent species.
... It has been known for one hundred years [12] that cryptorchidism can lead to testicular impairment, and as noted by Bedford [8], all of the scrotal mammals tested to date have been rendered infertile by this condition. Laboratory mice, for example, exhibit a complete inhibition of spermatogenesis and a 74% decrease in testis weight only 4 wk after being rendered cryptorchid [13]. ...
In natural populations, genetic variation in seasonal male sexual behaviour could affect behavioural ecology and evolution. In a wild-source population of white-footed mice, Peromyscus leucopus, from Virginia, U.S.A., males experiencing short photoperiod show high levels of genetic variation in reproductive organ mass and neuroendocrine traits related to fertility. We tested whether males from two divergent selection lines, one that strongly suppresses fertility under short photoperiod (responder) and one that weakly suppresses fertility under short photoperiod (nonresponder), also differ in photoperiod-dependent sexual behaviour and responses to female olfactory cues. Under short, but not long, photoperiod, there were significant differences between responder and nonresponder males in sexual behaviour and likelihood of inseminating a female. Males that were severely oligospermic or azoospermic under short photoperiod failed to display sexual behaviour in response to an ovariectomized and hormonally primed receptive female. However, on the day following testing, females were positive for spermatozoa only when paired with a male having a sperm count in the normal range for males under long photoperiod. Males from the nonresponder line showed accelerated reproductive development under short photoperiod in response to urine-soiled bedding from females, but males from the responder line did not. The results indicate genetic variation in sexual behaviour that is expressed under short, but not long, photoperiod, and indicate a potential link between heritable neuroendocrine variation and male sexual behaviour. In winter in a natural population, this heritable behavioural variation could affect fitness, seasonal life history trade-offs and population growth.
... In most mammalian species there is a radical change in the position of the testis during embryonic development, when each testis moves posteriorly and ventrally from its original position and descends into the scrotal sac. Degeneration of the germinal epithelium of the testes of such animals as a result of exposure to temperatures higher than those normally found in the scrotum has long been known (Griffiths, 1893; Crew, 1922; Moore, 1922; Moore & Chase, 1923; Moore & Quick, 1924). Assuming that the cooling mechanism of the scrotum plays an essential role in the regulation of L. L. Ewing and N. L. VanDemark tissue. ...
Investigations were conducted on the in-vitro metabolic activity of rabbit testicular tissue after exposing the testis to abdominal temperatures for 2, 6 or 24 hr. Metabolic activity increased with the shorter exposure and then significantly decreased as compared with that of normal testicular tissue. Tissue treated in this way recovered its normal metabolic activity when subjected for 30 min to an ice-cold glucose solution. Tissues exposed to abdominal temperature for 24 hr were found to contain 12 % less glucose and 27 % less lactic acid than control tissues. This study suggests that spermatogenic arrest which results from exposure of the testis to elevated temperatures may be caused by reduced levels of substrate in the tissue.
... It has been known for one hundred years [12] that cryptorchidism can lead to testicular impairment, and as noted by Bedford [8], all of the scrotal mammals tested to date have been rendered infertile by this condition. Laboratory mice, for example, exhibit a complete inhibition of spermatogenesis and a 74% decrease in testis weight only 4 wk after being rendered cryptorchid [13]. ...
The cane mouse (Zygodontomys brevicauda) breeds year-round on the hot llanos of Venezuela, only 8 degrees above the equator. The reproductive responses of the males of this species to heat were compared with those of a temperature zone rodent, the white-footed mouse (Peromyscus leucopus). When tested at different ambient temperatures, the movement of the testis in relation to the scrotum was similar in the two species, but the cane mouse's testis proved to be much more resistant to maintenance at core body temperature. In two experiments, cryptorchid cane mice experienced only a 24% and a 5% decrease in testis weight, and almost all of these males showed normal spermatogenesis and sperm storage. In comparison, cryptorchid white-footed mice showed a 58% drop in testis weight, a total inhibition of spermatogenesis, and a complete or near absence of stored sperm in all males. A mating test demonstrated that cane mice indeed remain fertile for at least 2 to 3 mo after being rendered cryptorchid. Normal numbers of these males when paired with females fathered normal litters. It is noted that the relative insensitivity of the testis of the cane mouse to heat might actually be more representative of scrotal mammals in general than is suggested by our present perspective, which has been developed on the basis of study of humans and mammals from cool climates rather than the tropics, where most mammals live.
... testes to the abdomen (Griffiths, 1893; Glover, 1960), or from In all, 16 Large White gilts weighing ~85–98 kg and aged 5.5–7 months were purchased from a local breeding farm. They were nature's own experiment of cryptorchidism (John Hunter, housed as groups of 3–5 animals in open-fronted indoor pens in the After infra-red recording was completed, and inspection and photography of the ovaries, the abdominal incision was closed in Department of Veterinary Clinical Studies, bedded on straw, and fed a standard pelletted diet twice daily; water was available ad libitum. ...
In order to establish appropriate culture temperatures for in-vitro maturation of pig ovarian oocytes, large Graafian follicles (7-10 mm diameter) were sensed by infra-red technology during the latter part of a spontaneous oestrous cycle. Temperatures were measured under systemic anaesthesia almost instantaneously upon revealing the ovaries at mid-ventral laparotomy. Temperature differentials were observed within all 16 ovaries sensed in 14 animals. Ovaries were always cooler than deep rectal temperatures (mean rectal temperature was 38.0 +/- 0.4 degrees C; range 37.5-38.6 degrees C) and mature follicles always cooler than ovarian stroma (35.6 +/- 0.3 degrees C versus 37.3 +/- 0.2 degrees C respectively; P < 0.01). Such follicles were frequently 1.5-1.8 degrees C cooler than the adjacent stroma, the mean being 1.7 +/- 0.4 degrees C. Small Graafian follicles (< 5-6 mm diameter) and recent ovulations did not show this differential. The control experiment of excising an ovary, deep freezing it in liquid nitrogen, and then restoring it to the body cavity before further sensing indicated that intra-ovarian temperature gradients depended on the activity of living tissues and/or a functional blood supply. Furthermore, calculation of anticipated rates of cooling for exposed Graafian follicles strongly suggested that artefacts could not have been solely responsible for the observed temperatures. Endothermic reactions within mature follicles were thus brought into focus. It is concluded that follicular temperatures may influence the meiotic progression and cytoplasmic maturation of oocytes and act to regulate enzymatic activity in the biosynthetic pathways for steroid and/or peptide hormones.
... The overwhelming purpose of this migration away from the abdomen is thought to be for cooling, although whether such migration was initially prompted by the requirements of the epididymis for maturing and storing spermatozoa below abdominal temperature (Glover and Nicander, 1971; Glover, 1973; Bedford, 1978) or of the gonad for protecting the labile processes of spermatogenesis and spermiogenesis from temperature-induced errors (Ehrenberg et al., 1957; Setchell, 1978; Waites and Setchell, 1990) remains uncertain. Even so, as demonstrated by surgical restoration of a testis to the abdomen (Griffiths, 1893; Glover, 1960) or by nature's own experiment of cryptorchidism , the gonad itself is critically sensitive to ambient temperature. ...
Using an infra-red camera, domestic pig ovaries were thermo-imaged almost instantaneously at laparotomy or within a closed
abdomen by endoscopy. Rectal and jugular vein temperatures were recorded using thermo-probes. Graafian follicles (7–10 mm
diameter) were cooler than ovarian stroma in all experimental models examined, and both compartments were cooler than rectal
and jugular temperatures. The mean difference between follicles and stroma in 73 observations was 1.3 ± 0.1°C. When thermo-imaged
under the fimbriated extremity of the Fallopian tube, follicles and stroma could still be distinguished. Follicles cooled
slightly more rapidly than adjoining stroma during the first 10 s of a 60 s recording interval, after which curves for the
two tissues remained parallel. Arresting ovarian blood supply for 5 min had a negligible influence on the temperature differentials.
Endoscopy in three models recorded mean differentials between follicles and stroma of 0.6 ± 0.1°C to 1.1 ± 0.1°C. It is concluded
that temperature gradients do exist in the ovarian tissues of mature animals, and that these are generated at least in part
as a consequence of endothermic reactions within Graafian follicles.
Herein, we compare the different experimental regimes used to induce testicular heat stress and summarise their impact on sperm production and male fertility. Irrespective of the protocol used, scrotal heat stress causes loss of sperm production. This is first seen 1–2 weeks post heat stress, peaking 4–5 weeks thereafter. The higher the temperature, or the longer the duration of heat, the more pronounced germ cell loss becomes, within extreme cases this leads to azoospermia. The second, and often underappreciated impact of testicular hyperthermia is the production of poor‐quality spermatozoa. Typically, those cells that survive hyperthermia develop into morphologically abnormal and poorly motile spermatozoa. While both apoptotic and non‐apoptotic pathways are known to contribute to hyperthermic germ cell loss, the mechanisms leading to formation of poor‐quality sperm remain unclear. Mechanistically, it is unlikely that testicular hyperthermia affects messenger RNA (mRNA) abundance, as a comparison of four different mammalian studies shows no consistent single gene changes. Using available evidence, we propose two novel models to explain how testicular hyperthermia impairs sperm formation. Our first model suggests aberrant alternative splicing, while the second model proposes a loss of RNA repression. Importantly, neither model requires consistent changes in RNA species.
A large body of research confirms the vulnerable nature of spermatogenesis to relatively small increases in testicular temperature. Other physical properties of electromagnetic and ultrasound waves have additive or synergistic effects to those of heat and allow disruption of spermatogenic processes at minimal temperature elevations. In addition there is a rebound in sperm count following heat-induced suppression of spermatogenesis. These findings suggest the theoretical viability of testicular heating as a reversible method of male contraception in humans. However before heating techniques can be used for male fertility control several questions remain to be investigated. The lowest effective doses and the lowest frequency of application of each method of testicular heating necessary for inducing and maintaining a reliable infertile state must be established. It must be determined whether long-term exposure leads to permanent damage or compromise of testicular elements or functions and whether exposure to simple heat electromagnetic waves or ultrasound induces significant changes in the biological constituents of human semen. Also unclear is the exact mutagenic potential of thermal agents on the human gonads. Another research question is whether scrotal warm sensory input rises during testicular heating to a level that is sufficient to alter body core temperature. Rapidly advancing knowledge of biologic constituents of human semen and the increasingly available detection methods of these constituents will enhance research in these areas. It is through such research that the safety efficacy and applicability of thermal manipulation of spermatogenesis as a method of male contraception will be established or refuted.
Testicular maldescent is a risk factor for testicular cancer and for infertility and is more prevalent in men presenting with fertility problems. Cancer therapy may result in infertility. Sometimes testicular malignancy is first detected because cancerous cells are identified in the seminology laboratory (Howard et al. 1989).
The objective was to assess the effect of a short-term scrotal hyperthermia in dogs on quantitative and qualitative ejaculate parameters, testicular blood flow and testicular and epididymal histology. After a control period, the scrotum of seven normospermic adult beagle dogs was insulated with a self-made suspensory for 48 h. Nine weeks later, two animals were castrated, while in five animals, scrotal hyperthermia was repeated. Dogs were castrated either 10 or 40 days thereafter. In each phase of scrotal insulation, average scrotal surface temperature increased by 3.0°C. Semen was collected twice weekly throughout the experiment. Total sperm count did not change after the first hyperthermia, but it slightly decreased after the second (p < 0.05). Profiles of sperm morphology and velocity parameters (CASA) rather indicated subtle physiological variations in sperm quality than effects of a local heat stress. Chromatin stability of ejaculated spermatozoa as indicated by SCSA remained constant throughout the experiment. Perfusion characteristics of the gonads, that is, systolic peak velocity, pulsatility and resistance index at the marginal location of the testicular artery, did not change due to hyperthermia (p > 0.05). Histological examination of excised testes and epididymides for apoptotic (TUNEL and activated caspase-3) and proliferating cells (Ki-67 antigen) indicated only marginal effects of scrotal insulation on tissue morphology. In conclusion, a mild short-term scrotal hyperthermia in dogs does not cause substantial changes in sperm quantity and quality. In contrast to other species, canine testes and epididymides may have a higher competence to compensate such thermal stress.
Germ cell apoptosis have been recognized as an important event in order to regulate daily sperm production in humans and in animal models as well. Several studies in rat, mouse and monkeys have shown that testicular mild heat stress (43°C for 15 min) induces a massive increase in germ cell apoptosis along with oxidative damage and activation of diverse signaling pathways. In addition, heat stress produces a decrease in sperm viability, increase sperm damage and decrease embryo quality. In human, testis exposure to heat stress may result from occupational exposure, life style or clinical disorders including cryptorchidism or varicocele. Thus, in the past years researchers have focused on two major areas; the first is to find the molecular signaling pathway trigger by heat stress, and 2) to seek for new molecules with antioxidant abilities which may prevent germ cell apoptosis and/or to improve sperm performance. However, the link between heat stress and male infertility in humans still remains controversial. Here we critically review the available literature in human and animal models, and we propose a new model
The production of testicular androgen-binding protein (ABP), as a measure of Sertoli cell function, was studied after unilateral or bilateral experimental cryptorchidism in adult rats. Two or 4 weeks after the testis had been translocated to the abdomen, no major changes were found in the concentration of ABP per mg protein, although there was a marked and progressive decrease in ABP content per testis. However, the rate of ABP production was greatly decreased, as measured by the accumulation of ABP during 16-h ligation of the efferent ducts or by the production of ABP by testis mince in an in vitro system. This indicates that the Sertoli cell function is severly impaired by the intra-abdominal position.
A method is described for the preparation of highly purified fractions (greater than 80% pure) of immature spermatids (round, steps 1--8) from rat testes by centrifugal elutriation in sufficient yields for biochemical studies when four rat testes are used. Electron microscopy established the identity of the cells and demonstrated that the cell membrane is intact. Some cells develop nuclear and cytoplasmic vacuoles during the 2 h required for preparation. Immature spermatids prepared by this method use glucose with an increase in oxygen consumption, lactate production, and protein synthesis over control levels (no glucose). The testicular cell suspension from which spermatids are separated, like whole testis and spermatids themselves, show higher incorporation of amino acids into TCA-precipitable material at 34 degrees C than at 38 degrees C and in the presence of glucose. A subcellular system prepared from immature spermatids with excess ATP shows greater incorporation of amino acids into TCA-precipitable material at 34 degrees C than at 38 degrees C. This difference does not result from increased breakdown of protein. It is concluded that body temperature (38 degrees C) inhibits some aspect(s) of protein synthesis in addition to previously reported effects on amino acid transport and production of ATP (Means and Hall. 1969. Endocrinology. 84:285--297.).
Interestingly enough, the earliest references to alteration of the testis have to do with varicocele. Celsus (Born ca. 25 AD) spoke of cirsocele (varicocele): “When the disease has spread also over the testicle and its cord, the testicle sinks a little lower and becomes smaller than its fellow inasmuch as its nutrition has become defective.”
Summary The effects of a “moderate dose” of heat (43° C for 15 min) 1 1/2 and 3 h after treatment and of a short-time experimental
cryptorchidism (12 and 24 h) on rat spermatogenic cells were studied using a method based on phase-contrast microscopy of
freshly isolated, accurately identified and unstained cells. Three hours after heat treatment, a dull zone covering stages
from X to I was detected by transillumination of freshly isolated tubules. This was caused by degenerating pachytene spermatocytes
in stages X-XII, diakinetic and dividing spermatocytes in stages XIII and XIV and stage 1 spermatids, which had typical bright
phase-change characteristics in isolated condition.
A different kind of cellular injury was produced by short-time experimental cryptorchidism, the dull segment of freshly isolated
tubules covering only stages I and II after 48 h cryptor-chidism. Young spermatids immediately after the 2nd meiotic division
at stage I and early pachytene spermatocytes, mainly at the end of stage I and in stage II were the degenerating cell types.
The first signs of the cellular damage observable in freshly isolated spermatogenic cells were traced using 12 and 24 h cryptorchidism.
A disorganization of cytoplasmic organelles of young spermatids and a dull phase-change alteration of early pachytene spermatocytes
were the first detectable signs of degeneration. All other spermatogenic cells were without any severe damage as judged by
the present technique.
Unilateral artificial cryptorchidism was produced in Sprague Dawley rats for periods of 5, 10, and 20 days. In all animals examined, scrotal testes retained their normal morphology and spermatogenic activity. By contrast, the cryptorchid testes exhibited various degrees of degeneration and sloughing of the germinal epithelium. The Sertoli cells remained morphologically intact in both scrotal and cryptorchid testes. No indication of Sertoli cell atrophy was evident, as judged by the morphology of their nuclei. The incorporation of tritiated leucine by Sertoli cell nuclei resulted in approximately a 2 fold increase in uptake after 20 days of cryptorchidism, as compared with scrotal testis nuclei. Autoradiographic evaluations of Sertoli cell nuclei showed that the grains were normally distributed over both scrotal and cryptorchid testes nuclei. These results were interpreted to mean that Sertoli cell nuclei of both scrotal and cryptorchid testes display a spectrum of protein synthetic capabilities. The stimulation of this synthetic activity by the cryptorchid lesion increases the capacity of the nuclei to synthesize proteins in a manner proportional to their ability under normal scrotal conditions.
1.1. One testis of each of five wallabies was made cryptorchid.2.2. The cryptorchid testis appeared normal 24 hr after the operation, but later, increasingly marked histological changes were seen.3.3. The histological changes in the cryptorchid testis, 2, 4 and 7 days after surgery, were similar to those described in eutherian mammals.4.4. Testicular blood flow was similar in cryptorchid and scrotal testes.
Summary The immediate effects on rabbit spermateleosis of experimental cryptorchidism for 12, 24, and 48 hs were studied in the electron
microscope. Prominent changes were observed in the nucleus, in the acrosome system, in the forming tail, in the perinuclear
ring, and in the postacrosomal dense lamina. The nucleus showed abnormal shape and various chromatin defects. Local dilations
of the subacrosomal space were very common and various abnormalities of the acrosome were observed in most stages of spermateleosis.
Split coarse fibres, disintegration of the fibrous sheath, and defects of the mitochondrial sheath were observed in the forming
tail. Total or partial disintegration of the perinuclear ring as well as defects in the postacrosomal dense lamina were found.
Various other changes were also found in some spermatids. Some possible biochemical explanations of the changes are suggested,
and similarities to changes described in cases of spontaneous sterility are briefly discussed.
PIP
4 different studies on the effect of vasectomy on the testis in canines and humans are reported. Testicular biopsies were performed at certain intervals and the results in both humans and dogs were nearly identical. It was found that spermatogenesis 2 to 3 weeks after vasectomy remained unchanged with accumulation of spermatozoa in the tubules. Between 3 and 6 weeks, progressive spermatogenic arrest with few spermatozoa and decreased spermatids were observed. Between 100 and 300 days, occasional mature sperm were found in the tubules indicating a return of spermatogenesis. Meiotic studies showed this to be an arrest in early prophase. It is theorized that spermatogenesis may be sensitive to pressure changes in the tubular system.
Mature male Sprague-Dawley rats were divided into two groups. One group was rendered bilaterally cryptorchid and the other served as intact controls. Seven, 14, 21, and 28 days post surgery, five animals from each group were sacrificed, blood samples were collected, and the levels of serum gonadotropins and steroids were subsequently determined by RIA. The testes were removed and used to determine zero time concentrations of testosterone (T), T production in vitro, the zero time concentrations of 17β-estradiol (E2), and the levels of cytoplasmic estrogen receptor (E2R). LH levels in the cryptorchid group increased significantly over the controls at 7 days and remained elevated through 28 days; a similar increase in FSH levels was also detected. Cryptorchidism produced no appreciable effects on the serum steroid levels. No significant difference was detected in the levels of T between the cryptorchid and control groups, and no significant difference in serum E2 levels was detected between the two groups through 21 days; however, a slight but significant decrease in E2 below the control level was observed in the cryptorchid group at 28 days. The concentrations of T in the testis remained relatively constant in the controls, while the levels in the cryptorchid animals increased significantly above controls at 14 days and remained significantly elevated through 28 days. A similar increase above controls in the 3-h T production in vitro was found to be significant at 14 days (P < 0.05) and 28 days (P < 0.01). The levels of testicular E2 remained relatively unchanged up to 28 days, at which time the E2 levels were significantly reduced below control levels. However, when the data were expressed as content per testis, the levels of both steroids and T production in the cryptorchid group were found to be reduced compared to control levels. The demonstration that bilateral cryptorchidism resulted in a decreased production of testicular steroids suggests damage to or loss of Leydig cells. The cytoplasmic E2R-binding capacity, expressed as femtomoles of E2 per mg cytosol protein, was found to be increased 2- to 4-fold over that of the control group; this increase was detectable as early as 7 days post surgery. Thus, concomitant to the reduced steroid production, the E2R-binding capacity, which is localized in the Leydig cell, was dramatically increased. This indicates that Leydig cell responsiveness, as reflected by androgen production, was impaired by cryptorchidism. The adverse effects of cryptorchidism, however, did not extend to all functions of the Leydig cell, since E2R binding was enhanced. The demonstration that serum gonadotropins increased while serum steroids remained unchanged after cryptorchidism suggests the possibility that testicular factors other than T and E2 might be involved in the feedback control of the hypothalamic-pituitary axis.
When rats were made unilaterally cryptorchid at 17 days of age (before spontaneous descensus), the further maturation of the testis was prevented. At 34 days of age, the abdominal testis was smaller than the scrotal testis and showed less secretion of the Sertoli cell specific androgen binding protein (ABP). In 120-130 days old rats that were made bilaterally cryptorchid at 17 days of age, testicular weight, histology, secretion of fluid and ABP were restored and testosterone secretion and fertility were normal if orchidopexy was performed at 33 days of age. If the orchidopexy was delayed until 59 days of age, the recovery of testicular function and morphology was only partial. The results show that in the rat, the testicular damage caused by cryptorchidism is reversible, if the abdominal testis is surgically descended during early sexual maturation.
The evidence for the lower temperature of the testes of many mammals is summarized, and the reasons suggested for the descent of the testes into a scrotum are discussed. Descriptions are given of the various techniques used for studying the effects of heat on the testis, whole body heating, local heating of the testes (by inducing cryptorchidism, scrotal insulation or immersion of the scrotum in a water bath), and heating of tissue or cell preparations in vitro. The effects of heat are discussed, effects on the testis (weight, histology, physiology, biochemistry and endocrinology), on the numbers and motility of spermatozoa in rete testis fluid and semen, on fertilizing ability of spermatozoa and on the subsequent development of the embryos produced when spermatozoa from heated testes are used to fertilize normal ova. The possible mechanisms for the damaging effects of heat are discussed, as well as the importance of heat-induced abnormalities in male reproduction in domestic animals and humans.
The testis is remarkable as a biologic system for its functional regulation by temperature. Not only does the testis function optimally at a relatively cool temperature, but core body temperature is lethal to germ cells. This temperature sensitivity has implications for clinical medicine, both in terms of understanding pathologic states and for therapeutic measures. Perhaps most important, the relationship between testis and temperature presents great opportunities for further elucidation of cellular control mechanisms, particularly with regard to gametogenesis.
The methods devised for male contraception are meager. The authors review the various nonhormonal methods applied for contraception including vas deferens interference and heat. The former comprises the no-scalpel vasectomy, percutaneous vasal injection, the "Shug" method, and the argon laser vasal photocoagulation. Heat methods used wet heat, and artificial cryptorchidism was created by testicular suspension. The testicle was suspended in the superficial inguinal pouch close to the scrotal neck using 2 methods: stitch and ball. Two recently developed methods for male contraception--polyester-induced azoospermia and prolactin injection--are described. The azoospermic effect of the polyester sling seems to be due to (1) creation of an electrostatic field across the intrascrotal structures, and (2) disordered thermoregulation. Prolactin administration as a contraceptive method is efficient and safe and has the potential to be developed as a male contraceptive. The methods, especially testicular suspension and polyester suspensors, are simple and easily applicable and were well accepted by the subjects.
Cryptorchidism is commonly used for research on spermatogenesis. However, there are few comparative investigations about the strain differences in mice, especially in long-term experiments. In the present study, the authors demonstrate its specific dynamics in the MRL/MpJ mouse strain, and discuss the cause of strain differences. In the mouse strains A/J BALB/c, C3H/He, and C57BL/6, after 2 weeks of experimental cryptorchidism, the ratios of the cryptorchid testis weight against the intact one were 0.38+/-0.05, 0.43+/-0.05, 0.38+/- 0.02, and 0.44+/-0.14, respectively. On the other hand, in the MRL/MpJ strain it was shifted to 0.69+/-0.08. The details of this strain difference were compared by calculation of germ cells with the Sertoli cell index at 2 weeks after operation. The indices of spermatogonia in all strains were not significantly different; however, in MRL/MpJ mice remarkable numbers of late spermatocytes and round spermatids were detected. The decrease of the testis weight ratio was similar until 10 days in the C57BL/6 and MRL/MpJ strains, but continued in C57BL/6 until 21 days, whereas in MRL/MpJ mice it plateaued after 10 days. Northern blot analysis for heat shock protein 70-2 using total RNA prepared from the cryptorchid and intact testes at 2 weeks after operation revealed that the expression was decreased in the cryptorchid testis of C57BL/6, but not MRL/MpJ mice. The results suggested that heat-resistant germ cells were present in MRL/MpJ, originating possibly from the genetic background.
Rat testes were confined to the abdominal cavity by operation. After 1 to 26 days they were excised, fixed with osmium tetroxide, sectioned, and examined with the electron microscope. Changes in the axial filament complex of the spermatid flagellum appeared 2 days after operation, and the arrangement of filaments in the middle- and main pieces of some spermatid tails was disordered as compared to the 9 + 2 filament arrangement in the tails of the control spermatids and in other flagella and cilia. In cross-sections, the filaments in the experimental material were nine or less in number, and each of them was single and dense. Occasionally some were double, and in those instances one filament was dense and the other was light and tubular. The central filaments were obscure. In longitudinal sections,the filaments were not parallel to the main axis of the flagella or to each other. It was assumed that the central filaments were more sensitive to the experimental conditions than the peripheral pairs of filaments. Furthermore, the light filaments of the peripheral pairs were more sensitive than the dense filaments. Besides the axial filament complex, the fibrous sheath which surrounds it in the main piece was also changed. The plasma membrane of the changed flagella disappeared or became fragmented.
The purpose of the study reported here was to define strain differences in spermatogenesis in cryptorchid testes in mice. Mice of strains A/J, BALB/c, CBA/N, C3H/He, C57BL/6 (B6), ddY and ICR were found to be sensitive to heat stress attributable to experimentally induced cryptorchidism. In contrast, mice of strains AKR/N (AKR), MRL/MpJ-+/+ (M+) and MRL/MpJ-lpr/lpr (lpr) were resistant to heat stress. Relative increases of apoptotic cells were detected in the sensitive group, but not in the resistant group. A decrease of proliferating cell nuclear antigen-immunoreactive cells after experimentally induced cryptorchidism was observed only in the sensitive group. These results suggested that heat stress-resistant germ cells were present in MRL and AKR strains, possibly originating from the genetic background.
The existence of a temperature gradient between the testis and deep body temperature has been accepted for many years. It is based on two simultaneous principles: cooling of the testis through the scrotal wall and transfer of heat between the testicular blood vessels. The ovary is positioned in the abdomen; a temperature difference parallel to the male system therefore seems less likely. However, the temperature of large follicles has been found to be 0.5 to 1.5 degrees C cooler than the ovarian stroma in rabbits, pigs and, probably, women. The temperature difference seems to be based on a heat-consuming process in the expanding follicullar fluid, and a local transfer of heat between intra-ovarian blood vessels. The reason for the temperature gradient is not yet known; one may speculate of a common reason for the cooling of the gamete in male and female.
After recalling male gonadal physiology in respect of tissue temperatures within the scrotal sac, and raising questions concerning abdominal testes, attention turned to mature Graafian follicles and ovarian stroma. Temperature gradients between such tissues were summarized for human, rabbit, pig, and cow, and generally fell in the range of 1.3-1.7 degrees C: follicles were always cooler than stroma. Measurements were made principally by means of a thermo-sensing camera at midventral laparotomy, but also using microelectrodes or thermistor probes sited in the follicular antrum of rabbits and pigs, respectively. When thermo-imaged under the fimbriated extremity of the Fallopian tube, mature pig follicles and stroma could still be distinguished. Such follicles cooled slightly more rapidly during the first 10 s of a 60-s recording interval, after which curves for the two tissues remained parallel. Arresting ovarian blood supply for 5 min had a negligible influence on the temperature differentials. Endoscopy in three models recorded mean differentials of 0.6 +/- 0.1 degrees C - 1.1 +/- 0.1 degrees C between follicles and stroma, but such follicles had not attained mature diameter. Temperature gradients were thought to be generated at least in part by endothermic reactions within mature follicles, reflecting hydration of large extracellular matrix molecules such as proteoglycans. A contribution to the cooling process from the products of leukocyte activity in the follicle wall and antrum could also be involved. Temperature gradients would be maintained locally by counter-current heat exchange mechanisms and, in this context, the microvasculature and lymphatic flow of individual follicles were found to be appropriate. Observations on the temperature of preovulatory follicles appear relevant to procedures of in vitro maturation and in vitro fertilization.
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