The three-dimensional architecture of the myosalpinx in mammals: an anatomical model for a functional hypothesis

A Review: Biomechanical Aspects of the Fallopian Tube Relevant to its Function in Fertility

The fallopian tube (FT) plays a crucial role in the reproductive process by providing an ideal biomechanical and biochemical environment for fertilization and early embryo development. Despite its importance, the biomechanical functions of the FT that originate from its morphological aspects, and ultrastructural aspects, as well as the mechanical properties of FT, have not been studied nor used sufficiently, which limits the understanding of fertilization, mechanotrasduction, and mechanobiology during embryo development, as well as the replication of the FT in laboratory settings for infertility treatments. This paper reviews and revives valuable information on human FT reported in medical literature in the past five decades relevant to the biomechanical aspects of FT. In this review, we summarized the current state of knowledge concerning the morphological, ultrastructural aspects, and mechanical properties of the human FT. We also investigate the potential arising from a thorough consideration of the biomechanical functions and exploring often neglected mechanical aspects. Our investigation encompasses both macroscopic measurements (such as length, diameter, and thickness) and microscopic measurements (including the height of epithelial cells, the percentage of ciliated cells, cilia structure, and ciliary beat frequency). Our primary focus has been on healthy women of reproductive age. We have examined various measurement techniques, encompassing conventional metrology, 2D histological data as well as new spatial measurement techniques such as micro-CT.

Oviductal motile response to penile cervical buffeting

OBJECTIVES

We investigated the hypothesis that the oviduct exhibits increased motile activity during cervical buffeting.

METHODS

The response of oviductal and uterine pressures to cervix uteri (CU) stimulation was recorded in 16 women (mean age 32.4+/-3.6 years) with normal menstrual history. Pressure measurements, performed by means of saline-perfused catheters introduced into each of the uterus and oviduct, were recorded upon both electrical and mechanical CU stimulation before and after CU anesthetization.

RESULTS

CU stimulation produced a significant uterine pressure decrease with no significant difference between electrical and mechanical stimulation. Latency recorded mean of 17.6+/-1.2 ms for electrical stimulation and 17.2+/-1.2 for mechanical stimulation. CU stimulation caused also significant pressure rise in ampullary and isthmic parts of oviduct and a decrease of intramural oviduct with no significant difference between electrical and mechanical stimulation. Mean latency of electrical and mechanical response was 18.7+/-1.1 ms and 19.1+/-1.1 ms, respectively. Uterine and tubal pressure showed insignificant response to stimulation of the anesthetized CU.

CONCLUSIONS

Cervical stimulation reduced uterine and intramural oviduct pressure and elevated pressure of ampullary and isthmic parts. These utero-tubal responses seem to be mediated through a reflex which we call "cervico-utero-tubal reflex" and to assist in sperm-ovum transport and fertilization.

Oviduct contractile response to vaginal distension: identification of vagino-tubal reflex

OBJECTIVE

The effect of vaginal distension on the oviduct contractile activity during penile thrusting at coitus could not be traced in the literature. We investigated the hypothesis that vaginal distension effects oviduct contraction, which assists in ovum transport along the oviduct.

METHODS

Oviduct pressure was measured upon vaginal condom distension in 16 women (mean age 32.2+/-1.2 years) scheduled for abdominal hernia repair and oviduct ligation for sterilization. The test was repeated after individual anesthetization of the vagina and oviduct.

RESULTS

Ten milliliters vaginal distension effected pressure elevation of the ampullary (AO) and isthmic (IO) parts of the oviduct (p<0.01, p<0.01 respectively) and a decrease in intramural oviduct (IMO; p<0.01). Twenty milliliters distension further increased the pressure in the AO and the IO (p<0.001, p<0.001) and decreased it in IMO (p<0.001). Vaginal distension with greater volumes produced an oviduct pressure response similar to that with 20 ml distension (p>0.05). Vaginal distension of anesthetized vagina or oviduct did not evoke the oviduct pressure response, but saline infusion did.

CONCLUSIONS

Vaginal distension seems to produce oviduct motile activity as evidenced by oviduct pressure changes, which appear to assist in sperm-ovum transport and fertilization. These oviduct changes are suggested to occur reflexly through the "vagino-tubal reflex." Pathologic changes of the oviduct presumably interfere with this reflex action, a point that needs to be investigated.

Three-dimensional architecture of the myosalpinx in the mare as revealed by scanning electron microscopy

The three-dimensional architecture of the myosalpinx in the mare was investigated by means of scanning electron microscopy (SEM) after removal of interstitial connective tissue with NaOH digestion. In the extramural portion of the tubo-uterine junction (TUJ), isthmus, and ampulla, the myosalpinx architecture is represented by a unique muscular structure which runs from the mesosalpinx to the base of the inner mucous folds. This unique muscular structure consists mainly of bundles of muscular fibers independent of one another, which show a multiple spatial arrangement and form a complex network. Such a muscular architecture is likely more suitable for stirring rather than pushing the embryos and gametes through the Fallopian tube.

The architecture of the myosalpinx in the sow as revealed by scanning electron microscopy

OBJECTIVE

To provide a definitive settlement of data on the architecture of myosalpinx in the sow in consideration of controversial data existing in literature.

STUDY-DESIGN

To allow direct visualization of muscular architecture, segments of tube from fifteen sows were investigated by means of scanning electron microscopy after the removal of interstitial connective tissue with NAOH digestion.

RESULTS

In the extramural portion of the tubo-uterine junction, in the isthmus and ampulla, the myosalpinx is mainly constituted by oblique bundles of variable length, which run around the tube and merge into the surrounding musculature, giving origin to a plexiform arrangement. In the ampulla the fibers join in short bundles variously oriented.

CONCLUSION

The three-dimensional architecture of the sow myosalpinx consists of muscular bundles independent of one another which follow multiple spatial arrangements and form a complex network. Such a muscular structure is likely more suitable for stirring rather than pushing the embryo and gametes.