G. Leyendecker

The dynamics of rapid sperm transport through the female genital tract: evidence from vaginal sonography of uterine peristalsis and hysterosalpingoscintigraphy

Vaginal ultrasonography of uterine peristalsis during the follicular phase of the menstrual cycle demonstrates an increasing frequency and intensity of subendometrial and myometrial peristaltic waves as the follicular phase progresses. During this time the numbers of contraction waves with a fundo-cervical direction decrease considerably in favour of waves of contraction with a cervico-fundal direction. There is evidence that rapid sperm transport through the female genital tract is passive and is provided by these uterine contractions. Using hysterosalpingoscintigraphy, rapid sperm transport was studied by placing technetium-labelled albumin macrospheres of sperm size at the external os of the uterine cervix and following their path through the female genital tract. Ascension of the macrospheres occurred immediately following deposition at the external os of the cervix. As early as 1 min thereafter, the macrospheres had reached the intramural and isthmical part of the tube. Quantitatively, the extent of ascension increased with progression of the follicular phase. While only a few macrospheres entered the uterine cavity and even fewer the tubes during the early follicular phase, the proportion of macrospheres that entered the uterine cavity increased dramatically during the mid-follicular phase despite continuing limited entry into the tube. During the late follicular phase there was considerable ascension of the macrospheres which was directed preferentially into the tube ipsilateral to the dominant follicle. These data indicate that rapid transport of the spermatozoa through the female genital tract is under the endocrine control of the dominant follicle, ensuring the preferential accumulation of spermatozoa at the site of fertilization.

Uterine peristaltic activity during the menstrual cycle: characterization, regulation, function and dysfunction

Unlike other smooth muscle organs, the uterine muscle was regarded to be normally functional for only a brief period, following a lengthy gestation. However, recently it has been shown that uterine peristalsis constitutes one of the fundamental functions of the non-pregnant uterus. Its morphological basis is the archimyometrium, which is the muscular component of the archimetra and which preserves a functional bipartition of the primarily unpaired uterus. Three types of uterine peristaltic contractions can be distinguished: cervico-fundal, fundo-cervical and isthmical peristaltic activity, which changes during the menstrual cycle and is controlled by the dominant ovarian structure via the secretion of sex steroids systemically and into the utero-ovarian vascular countercurrent system. Uterine peristalsis of the non-pregnant uterus is actively involved in very early reproductive processes, such as rapid and sustained directed sperm transport and high fundal implantation, as well as serving retrograde menstruation for the preservation of body iron content. Furthermore, it became apparent that hyper- and dysfunctions of this contractile activity, such as hyper- and dysperistalsis, might be causally involved in the development of pelvic endometriosis, uterine adenomyosis and infertility, as obtained from immunohistochemistry, vaginal sonography, hysterosalpingoscintigraphy and magnetic resonance imaging.

The Uterine Peristaltic Pump

Rapid as well as sustained sperm transport from the cervical canal to the isthmical part of the fallopian tube is provided by cervico-fundal uterine peristaltic contractions that can be visualized by vaginal sonography. The peristaltic contractions increase in frequency and presumably also in intensity as the proliferative phase progresses. As shown by placement of labeled albumin macrospheres of sperm size at the external cervical os and serial hysterosalpingoscintigraphy (HSSG) sperm reach, following their vaginal deposition, the uterine cavity within minutes. In the early follicular phase a large proportion of the macrospheres remains at the site of application, while a smaller proportion enters the uterine cavity with even a smaller one reaching the isthmical part of the tubes. In the mid-follicular phase of the cycle with increased frequency and intensity of the uterine contractions the proportion of macrospheres entering the uterine cavity as well as the tubes has significantly increased. In the late follicular phase with maximum frequency and intensity of uterine peristalsis the proportion of macrospheres entering the tube increases further at the expense of those at the site of application as well as within the uterine cavity. The transport of the macrospheres into the tube is preferentially directed into the tube ipsilateral to the dominant follicle, which becomes apparent in the mid-follicular phase as soon as a dominant follicle can be identified by ultrasound. Since the macrosphere are inert particles the directed sperm transport into the tube ipsilateral to the dominant follicle is not functionally related to a mechanism such as chemotaxis but is rather provided by uterine contraction of which the direction may be controlled by a specific myometrial architecture in combination with an asymmetric distribution of myometrial oestradiol receptors.

Adenomyosis as a disorder of the early and late human reproductive period.

Magnetic resonance imaging (MRI) allows the diagnosis of adenomyosis in vivo with a high sensitivity and specificity. Usually the diagnosis of adenomyosis is obtained from women in their fourth to fifth decade of life. However, recent data suggest that adenomyosis may develop much sooner in life, particularly in women with endometriosis. In order to test these suggestions, MRI of the uterus in 227 women with and without endometriosis was performed and the results were related to the age of the subjects (age groups: 17-24, 25-29, 30-34 and >34 years). The study revealed that the process of the development of adenomyosis, represented by an increased diameter of the dorsal junctional zone of the uterus as the imaging correlative of the invasion of basal endometrium into the junctional zone, had already commenced early in the third decade of life and progressed steadily during the fourth decade in women with endometriosis. Women without endometriosis showed almost no signs of adenomyosis up to the age of 34 years. Surprisingly, parallel in both groups of women, a marked increase in the incidence of adenomyosis could be observed beyond the age of 34 years, thus representing a common phenomenon in the age-related pathophysiological continuum of adenomyosis.

Oxytocin--a stimulator of directed sperm transport in humans.

Rhythmic peristaltic contractions of the muscular wall of the non-pregnant uterus, as well as rapid sperm transport from the vagina to the Fallopian tubes, have long been documented by means of vaginal sonography and hysterosalpingoscintigraphy. Uterine peristaltic activity reaches a maximum before ovulation and is controlled via oestradiol secretion from the dominant follicle systemically and into the utero-ovarian countercurrent system; it is also enhanced by oxytocin. In this study, the effect of oxytocin and its receptor antagonist atosiban on uterine peristalsis and thus directed sperm transport during the mid and late follicular phases was examined. Atosiban did not show any effect either on frequency or on pattern of the peristaltic contractions. However, oxytocin significantly increased the rapid and directed transport of radiolabelled particles representing spermatozoa from the vagina into the Fallopian tube ipsilateral to the site of the dominant follicle (P = 0.02, 0.04 and 0.02 after 1, 16 and 32 min of documentation respectively). It seems reasonable to assume that oxytocin plays an important, although not critical, role in the mechanisms governing rapid sperm ascension that, at least in humans, were developed to rapidly preserve an aliquot of spermatozoa following intercourse.

From physiology to clinics — 20 years of experience with pulsatile GnRH

The physiological and the pathophysiological basis of unvariant pulsatile administration of gonadotrophin-releasing hormone (GnRH) as well as the clinical results are reviewed. Pulsatile administration of GnRH not only proved to be a very effective treatment mode but also became an important tool for research in the central control of pituitary and ovarian function under normal and disease conditions.