Mechanism Of Sperm Transport Research Articles

Morphological analysis of interstitial cells in murine epididymis using light microscopy and transmission electron microscopy

Smooth muscle contraction of the epididymis plays an important role in sperm transport. Although PDGFRα-positive interstitial cells (PDGFRα (+) ICs) are thought to be involved in controlling smooth muscle movement via intercellular signaling, they have not yet been reported to date in the epididymis. Therefore, we aimed to investigate the morphological characteristics of PDGFRα (+) ICs in the interstitial space of the murine epididymis. Immunohistochemistry showed that PDGFRα (+) ICs co-labeled with CD34 (PDGFRα (+) CD34 (+) ICs were distributed in the interstitial space of the murine epididymis from the initial segment (IS) to the cauda of the epididymis. PDGFRα (+) ICs that were not co-labeled with CD34 (PDGFRα (+) CD34 (−) ICs) were observed just beneath the epithelium from the corpus to the cauda but not in the IS. Both types of PDGFRα (+) ICs were in close proximity to each other as well as the surrounding nerves and macrophages. In addition, PDGFRα (+) CD34 (−) ICs beneath the epithelium were also in close proximity to the basal cells. Using transmission electron microscopy, we identified ICs that possessed elongated and woven cellular processes and were in close proximity to each other, surrounding the cells in the interstitial space. In the murine epididymis, it is suggested that there are two subtypes of ICs that show different distribution patterns depending on the segment, which may reflect segmental differences in mechanisms of sperm transport, forming a cellular network by physical interactions in the murine epididymis.

Determination of Sperm Transfer Time and Retention times of different Regions of Hamster Epididymis

Most of the scientific researches deal with the epididymal sperm maturation but not with the storage of sperms in epididymis. The present study was carried out to determine sperm transfer time, sperm retention time and sperm motility in different regions of hamster epididymis after placing ligations. Ligations were made at the initial segment of the epididymes. The total number of sperm was assessed using the haemocytometer counting method and sperm counts were taken on defined time intervals starting from the 3 rd day to the 78 th day of postligation. Total sperm count was decreased 50% by 3 days in caput and corpus regions and by 15 days in cauda region. Yet, there were a few numbers of sperm in all regions of hamster epididymis even after 78 days of post-ligation. By 15 days, sperm motility was decreased rapidlyin all epididymal regions and the majority of sperms were immotile by the 24 th day of post-ligation. Both sperm counts; immotile and motile sperms in control side was significantly different compared to that of the ligated side of the epididymis (p< 0.05). Sperm emptying time was approximately 18 days in the caput alone, 14 days in the corpus and 46 days in the cauda. It is concluded that in the ligated hamster epididymis sperm transfer takes more than 78 days. The findings of the present study will be vital for future studies on mechanisms of sperm transport and sperm storage in the cauda epididymis in detail.

Motility Measurement of a Mouse Sperm by Atomic Force Microscopy

Eukaryotic flagella are responsible for the motile organelles that cause the migration of mammalian sperms. The lashing force and torque of the sperm flagellum contain critical information regarding the sperm health, as important evaluation factors for sperm screening. The objective of the study was to investigate the lashing force and torque of a sperm under physiological conditions using atomic force microscopy (AFM). At a distance of about 18.5 μm from its head-tail junction, a lashing force of 0.96 ± 0.20 nN was measured. Its corresponding lashing torque was 1.77(± 0.37)× 10(-14) N·m. The torque increases in proportion to the square of the head-tail junction distance. Our results reasonably conclude that the axonemal motility is linear dependent on the flagellum length of the sperm. Our developed measurement system can consistently determine the lashing force and torque of a sperm, which can contribute to further studies concerning the mechanism of sperm transport and fertilization.

Increased cervical electrical activity during oestrus in progestagen treated ewes: Possible role in sperm transport

The aim of this investigation was to characterize the pattern of cervical myoelectrical activity (EMG) in the sheep, during the periovulatory period, after synchronization of oestrus with progestagen and eCG. EMG was measured with a computerised modular system in five ewes previously fitted with a pair of monopolar Teflon needle electrodes in the muscle layers of the cervix. Each ewe was submitted to oestrus synchronization treatment with intravaginal progestagen sponge during 12 days, and the administration of 500 IU of eCG at the withdrawal of sponge. EMG was recorded in each animal during 19 h, starting 44 h after withdrawal of sponge. The number and duration of events were determined every hour during the experiment. Two distinct event durations were identified: one lasting less than 200 s and another lasting between 300 and 500 s. The two types of events analysed (less than 200 s and lasting between 300 and 500 s) had a similar pattern during the period of observation although they were not in synchrony. For events lasting less than 200 s, activity increased between 48 and 50 h after sponge withdrawal, with the peak of activity being observed between 51 and 53 h. For events of 300–500 s duration, the peak of activity was observed between 48 and 50 h after sponge withdrawal and activity was maintained until 51–53 h. The increase in cervical motility observed in progestagen–eCG treated ewes is in keeping with the increase in cervical activity observed by others in natural cycling animals, and suggests that exogenous hormones used in synchronization protocols had no deleterious action on cervical motility during periovulatory period. The enhanced activity of cervical muscle layer found around the time of mating and/or AI suggests it may play an important role as a regulatory mechanism of sperm transport. Taking advantage of the cervical responsiveness to various drugs, experimental modulation of cervical activity could be used to facilitate cervical sperm transport and consequent improve of fertility after cervical AI.

Ultrastructural and Rheological Properties of Bovine Vaginal Fluid and its Relation to Sperm Motility and Fertilization: a Review

The tubular genital organs of the mammalian female reproductive tract provide different luminal microenvironments that can act as an aid or a barrier to gamete transport and the first steps of embryonic development. The mechanism of sperm transport through the genital tract has not been fully established but, first of all, sperm cells encounter and need to overcome mucous-like secretions to reach the site where fertilization occurs. One of these secretions, vaginal fluid, is a complex biological product, which is mainly derived from cervical mucus. In this review, we focus on recent studies that describe the relationships between the ultrastructural and rheological properties of bovine vaginal fluid and sperm motion. In the light of this, we propose bovine vaginal fluid as a morphofunctional model for the study of sperm transport in mammals.

Endometriosis affects sperm–endosalpingeal interactions

The interaction between spermatozoa and the epithelium of the isthmic region of the uterine tube is thought to be an important part of the mechanisms of sperm transport to the site of fertilization and in preparing them for fertilization. However, it is unclear whether a dysfunction of this mechanism may contribute to subfertility in some individuals. The sperm-binding characteristics of the epithelium from the uterine tubes of three groups of women were examined: (i) eight with pelvic endometriosis (not involving the uterine tubes); (ii) five women who had been receiving zoladex injections to control their symptoms; and (iii) as controls 10 women undergoing an elective procedure for benign gynaecological problems but with no other pathology of the reproductive tract. Significantly more spermatozoa bound per unit area to the ampullary epithelium of the uterine tubes taken from women with a previous diagnosis of endometriosis. These findings suggest that the characteristics of sperm binding to tubal epithelium may be disrupted in women with a gynaecological pathology such as endometriosis. It is suggested that this may have the potential to interfere with the availability of freely motile spermatozoa, of the appropriate physiological status, to take part in fertilization. This may be a newly described mechanism by which endometriosis can cause infertility.

Vasectomy reversal.

Vasectomy reversal.

Fundamental aspects of sperm cryobiology: The importance of species and individual differences

While semen cryopreservation is successfully used for a few species, application to other species can be problematic. Here, I argue that species differences in female tract anatomy, subtle differences in sperm transport mechanisms, ability to time inseminations and deliver spermatozoa effectively are powerful determinants of fertility with cryopreserved spermatozoa. Poor sperm survival represents one major aspect of the problem and determining biophysical characteristics of the sperm plasma membrane is an established approach to solving it. However, this approach is unable to account for the consistent differences in post-cryopreservation sperm quality between individual males, an effect that is recognized in many species although only documented in a few. Searching for genetic differences between these individuals might offer a genomically-based direction in semen cryopreservation research. Cryopreservation of spermatozoa and spermatogenic cells for intracytoplasmic sperm injection has been developed primarily to deliver an intact genome and presents a very different set of technical problems.

Fate and distribution of seminal plasma proteins in the genital tract of the female rat after natural mating.

This paper describes the distribution and fate of seminal plasma proteins in the rat female genital tract after insemination, using immunological detection in tissue sections and in fluids collected from different regions. The localization of seminal plasma proteins in the uterus and the vagina correlated with that of spermatozoa, suggesting that passive transport mechanisms operate in these regions. No seminal plasma proteins were detected in the oviduct, indicating that their presence is probably restricted to the uterine environment. Possible mechanisms for eliminating seminal plasma molecules after copulation include leakage from the uterus after relaxation of the cervical muscles and endocytosis by the endometrial cells. Large amounts of both vesicular and coagulating gland proteins were detected in the vagina of females at the time of cervical relaxation, indicating that the first mechanism of leakage from the uterus after cervical relaxation operates. Immunocytochemical procedures were used and seminal vesicle antigens were detected inside uterine epithelial cells, which indicates that endocytosis is also a mechanism for elimination of these molecules after copulation. Western blot results suggest proteolytic cleavage as a third mechanism. However, coagulating gland antigens are neither endocytosed nor cleaved, and their elimination takes place only by backflow to the vagina. The seminal plasma distribution in experimental situations in which sperm transport is altered was also studied. The implications of our findings for mechanisms of sperm transport in the female are discussed.

Current approaches in the management of emissional dysfunction

This review article explored the mechanism of neural control of the seminal tract and sperm transport through it, to approach the rational management of emissional dysfunction. The identification of retroperitoneal and intrapelvic sympathetic nerves controlling seminal emission from the ejaculatory duct (SEED), the compensatory pathways for SEED after transection of hypogastric nerve, the mechanism of sperm transport through the vas deferens, and a new method to generate seminal emission were discussed.

Antegrade and retrograde fluid transport through the vas deferens.

Intraluminal pressure of the seminal tract at seminal emission from the ejaculatory duct and the mode of transport of cauda epididymal contents were investigated to explore the mechanism of sperm transport. Direct electrical stimulation of any site of the cauda epididymis and vas deferens, which generated nerve-transmitted muscle contraction, caused elevation of the intraluminal pressure only at the cauda epididymis, whereas stimulation of the testis, caput, and corpus epididymis caused no response. The dye instilled in the cauda was emitted into the urethra during the stimulation. Shortly after discontinuation of the stimulation, retrograde movement of residual dye in the vas resulted in its ultimate reentry into the cauda epididymis. Significant decrease of the muscle tonus just after contraction was observed at the cauda. Distension of the wall of the vas generated elevation of the intraluminal pressure only at the site distended. The above results indicate the presence of rapid antegrade and retrograde movement of the sperm and the crucial role of the cauda epididymis on the sperm transport.

Transport and Fate of Spermatozoa After Insemination of Cattle

Sperm capable of fertilizing ova reach the isthmus of cows about 8h after mating and remain in the caudal 2cm of the isthmus until ovulation. Then small numbers of sperm move to the site of fertilization at the junction of the isthmus and ampulla.Within a few hours after deposition of semen in the uterine body, most sperm have drained to the exterior in cervical mucus. By 12 to 24h after insemination, only a few percent of the sperm remain in the reproductive tract, and most of these are in the vagina.Contractions of the reproductive tract appear to be the primary mechanism of sperm transport. Flagellation of sperm is probably required for sperm to enter the folds of the cervix, and flagellation may be helpful or essential for sperm to pass through the uterotubal junction, move from the isthmus to the ampulla, and penetrate ova. High proportions of sperm undergo the acrosome reaction only in the ampulla on the side of ovulation and only after ovulation.The fertilization rate in cattle can be improved by use of semen from high fertility bulls and perhaps by timing insemination with semen from lower fertility bulls after the end of estrus.

Intra- and interspecies comparison of sperm migration through polyacrylamide gel as an index of spermatozoal viability

Sperm migration distance through a polyacrylamide gel mimicking cervical mucus was compared among seven species: dog, cat, goat, ram, clouded leopard, dorcas gazelle, and Eld's deer. Freshly collected spermatozoa were evaluated microscopically and then assayed for migration distance in gel-filled capillary tubes in raw or diluted concentrations or after longevity declines in sperm motility and progressive status. Sperm count per milliliter of ejaculate and sperm percent motility ratings varied (P < 0.05) among selected species. Undiluted ejaculated spermatozoa from all species, except the clouded leopard, penetrated the polyacrylamide gel. Migration distance (mm) was different (P < 0.05) among species and not clearly correlated to concentration or motility factors. Although sperm concentrations in the dog and Eld's deer were similar, average migration distance of deer sperm was more than fourfold greater (P < 0.01) than that of dog sperm. The sperm motility rating for the gazelle was greater (P < 0.05) than that for the cat; however, penetration distance in the cat was more than twice as great (P < 0.05) as that in the gazelle. Species also varied in migration response after altering sperm concentration: Halving the sperm count of the dog, gazelle, and Eld's deer had no effect, but the same procedure decreased (P < 0.05) penetration distance in the goat and ram. No migration was observed in any species at a sperm concentration of 25 × 106 cells or less. Within species a decline in sperm percent motility-progressive status ratings was correlated (P < 0.05) to a subsequent decrease in penetration distance. These results provide a comparative assessment of sperm cell migration through a synthetic cervical mucus and suggest that this test may be a useful adjunct in evaluating reproductive potential. However, the assay is specific in interpretive merit, as sperm penetration distance within a single batch of gel is markedly variant among species and in some species dependent on sperm concentration. This interspecies specificity in sperm migration through a homogeneous gel suggests intrinsic species variance in sperm cell-cervical mucus interaction, suggesting that this assay could be valuable in future studies of the mechanism of sperm transport.

Sperm Survival and Transport in the Female Reproductive Tract

Fertilization failure, mostly due to absence of sperm in the oviducts, is a major cause of reproductive inefficiency of farm animals. Sperm may be transported to the oviducts of cattle and sheep within a few minutes after mating or insemination, but these sperm probably fertilize few ova. Slower transport, with establishment of sperm populations in each segment of the reproductive tract, requires a few to several hours. In swine, sperm capable of fertilizing ova reach the oviducts in less than 1h. Smooth muscle contractions of the reproductive tract, ciliary beats, fluid currents, and flagellar activity of sperm are primary mechanisms of sperm transport. Sperm become hyperactive in the oviducts in association with capacitation. Most sperm in an inseminate drain from the female reproductive tract within a few minutes or hours after insemination; remaining sperm are removed from the tract by slower drainage or phagocytosis.Sperm survival and transport in estrous ewes is reduced drastically by pastures with high estrogen content and by regulating estrus with progestogen or prostaglandin F2α. The cervix is the initial site of inhibition of sperm transport in ewes, and endocrine imbalances probably are the basis of inhibition. Sperm transport problems generally are associated with immobilization and death of sperm in the uterus and anterior segments of the cervix within 2h after mating. After gilts are inseminated with frozen-thawed semen, relatively few sperm are retained in the reproductive tract, apparently accounting for lowered fertilization rates.Sperm transport has been improved by adding to semen or administering to females such compounds as prostaglandin F2α, oxytocin, estradiol, phenylephrine, or ergonovine. Estradiol, prostaglandin F2α, phenylephrine, and ergonovine administered to rabbits at insemination each increased fertilization rates.

Morphological and physiological factors involved in the contractility of the spermatic cord and ductus deferens of the opossum (Didelphis albiventris).

The opossum spermatic cord is characterized by a thick skeletal muscle coat, provided by the great development of the cremasteric muscle. Acetylcholine induced a powerful contraction of the spermatic cord placed in an organ bath containing Heller's solution. This contraction was blocked by curare but not completely by atropine as is usual for skeletal muscle. However, the ductus deferens did not respond to acetylcholine or catecholamines under the same conditions. Specific histochemical methods for both catecholamines and acetylcholinesterases revealed that the ductus deferens musculature, composed mainly of circular fibres, is richly innervated by adrenergic and presumed cholinergic nerve fibres. The lack of responsiveness to the neurotransmitters could be explained by the absence of longitudinally arranged muscle. It is suggested that in the opossum the cremaster could participate in the mechanism of sperm transport.

The mechanisms and analysis of sperm migration through cervical mucus.

The migration of spermatozoa through cervical mucus has been studied extensively by physiologists and clinicians. Yet our understanding of this biological phenomenon remains superficial. This has been due at least in part to a lack of scientific objectivity in the experimental procedures employed, as well as a tendency to rely upon phenomenological thinking rather than fundamental principles of chemistry and physics. In this chapter our attention will be directed initially to the biophysical context within which the mechanisms of sperm transport in cervical mucus should be considered. Our current knowledge of those mechanisms will be summarized, and some of the applicable experimental techniques and mathematical models of analysis will be discussed. Finally, some new strategies for future investigation will be suggested. We will bring the reader’s attention to a number of scientifically sound and biologically relevent studies, but we will not attempt a comprehensive survey of the research in this area. For this information the reader is referred to a number of recent reviews on sperm transport1 and cervical mucus.2,3,4,5 In beginning this chapter it should be emphasized that among mammals it is primarily the ruminants and primates which produce substantial amounts of cervical mucus, and it is to these species that our comments will apply. The human is by far the best studied of these species and most of the specifics of our discussion will refer to human sperm-cervical mucus interaction.

Mechanical properties of the mammalian vas deferens. I. In the passive state

Knowledge of the mechanical properties of the vas deferens is important in order to understand the mechanical interaction between an intravasal device (IVD) and the vas deferens--a necessary step for successful long-term implantation. It is equally important in order to understand the mechanism of sperm transport through the vas, with or without an IVD implant, by means of quantitative mechanical models. Experiments were performed, in vitro, on vas deferens from rat, bull, and rabbit, to determine its mechanical properties in the passive state. The data consist of (1) load response to simple extension and cyclic extension, (2) extensional response to cyclic loading, and (3) stress relaxation response at constant extensions. The load-elongation behavior is characterized by Fung's exponential model T = (T* + beta)e alpha(lambda-lambda*) - beta quantitatively, where T is the Lagrangian or engineering stress (current force in the specimen divided by the original area of cross section) (dyn/cm2), T* is a convenient stress value (dyn/cm2), alpha is a parameter characterizing material elasticity (dimensionless), beta is a second material parameter (dyn/cm2), lambda is a stretch ratio (dimensionless) equal to l/l0, where l is the instantaneous length of the specimen (cm) and l0 is its reference length measured at 2-gram-force (1 gram force = 981 dyn) applied load (cm), and lambda* is the stretch level corresponding to T* (dimensionless). The vas appears to behave as a viscoelastic material and its reduced relaxation function may be dependent on the initial level of stretch. The cyclic-loading and cyclic-extension data give evidence of internal damping mechanisms, which make the loading curves different from the unloading curves (hysteresis). Also, the mechanical behavior of the vas is found to be altered by repeated loadings in quick succession. It is likely that cyclic loadings, in vivo, occur at much lower levels of stress and thus cause negligible damage, or that there are natural mechanisms which repair the damage. The behavior of tissue from different species of animals are qualitatively similar, although the tissue from the larger-size animal is likely to be stronger and stiffer. Due to very little interweaving between the muscle fibers of the longitudinal and circumferential layers, the data reported reflect the properties of the longitudinal layers only. Because the muscular structure of the three layers is very similar, the properties of the circumferential layer may be extrapolated.

International Symposium on the Biology of Spermatozoa: Transport, Survival, and Fertilizing Ability

Testicular fluid composition and structure epididymal spermatozoa patterns of sperm transport in women and nonhuman primates physiologic mechanisms of sperm transport and survival of spermatozoa in mammals and lower forms of life were topics of papers at the international symposium on the Biology of Spermatozoa Nouzilly France. Development of new contraceptives which would be detrimental to sperm transport in the female reproductive tract is advocated via intravaginal intracervical intrauterine or intraoviductal medicated devices. Capacitation and the 3 enzymes involved in this process are discussed as well as the process of fertilization. 15 areas are suggested for future research and development.

The swimming of spermatozoa in an active channel

Sperm transport in the human cervix is a vital step in the process of fertilization, and the roles of the cervix and the cervical mucus have been extensively discussed and investigated. A mechanism to explain sperm transport through the cervical mucus based on a dynamic interaction between the cervical mucus and the swimming sperm has been suggested by Odeblad. A mathematical model of Odeblad's proposed mechanism of sperm transport in the cervix is presented which idealizes the geometry as a self-propelling infinite sheet in a two-dimensional channel. The sheet propels itself by propagating waves of lateral displacement. The channel walls are allowed to vibrate as proposed by Odeblad as right traveling waves, left traveling waves or standing waves. The propulsive velocity and energy expended by the sheet and flow rates in the channel are computed. These results are presented and conclusions are given concerning the effect of wall oscillations on self propelling sheets. The conclusions of Odeblad's theory are contrasted with the results of the model.

Sperm Transport Through Vas Deferens: Review of Hypotheses and Suggestions for a Quantitative Model

Study of the mechanism of sperm transport through the vas deferens stems from the need to develop acceptable male contraceptive devices or procedures. The object of this paper is to review all the hypothese related to the innervation structure and function of the vas. Also considered are the experimental data and theoretical analyses necessary for understanding seminal fluid transport through the vas. Similarities in structure and function of the ureter are noted. Histologically the vas deferens lumen is bounded by a 3-layer musular wall. The inner and outer layers of smooth muscle wall are arranged longitudinally. The middle layer is circumferential. The vas deferns epididymis prostate and seminal vesicles have only an autonomic nerve suppply via the inferior hypogastric plexus. Studies of the fine details are described as they occur in man and experimental animals. Experiments suggest that the innervation of the vas is seriously damaged by local anesthesia used for vasectomy or reanstamosis when attempted. However the mechanisms of veurotransmission in the vas remain controversial. The various theories of muscular activity of the vas are reviewed. These data may be useful in the design of reversible vas occlusion devices. The improved understanding may suggest simple and effective methods of reversible vasectomy.