Dynamics of the ampullary-isthmic junction in rabbit oviduct

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.

Identification of novel and known ovary-specific genes including ZP2, in a marsupial, the stripe-faced dunnart

During the early stages of oogenesis, oocyte-specific factors, synthesized by and stored within the oocyte, play critical roles during oogenesis, folliculogenesis, fertilization and early embryonic development in the mouse. The identification of marsupial maternal factors, expressed specifically in the ovary or oocyte, may provide an insight into the conserved evolutionary mechanisms that drive mammalian oocyte development to cleavage stages. In this study, 10 clones including dunnart ZP2 and c-mos, isolated by cDNA representational difference analysis, were validated by RT-PCR for ovary-specific expression. This novel combination of techniques to isolate ovary-specific genes has identified three novel genes with ovary-specific expression. Both dunnart ZP2 and c-mos exhibited ovary-specific expression, making this study the first isolation of c-mos in a marsupial species. Dunnart ZP2 expression was examined in detail by in situ hybridization and results indicate oocyte-specific expression of dunnart ZP2 in the cytoplasm of oocytes of primordial, primary and secondary follicles with expression being highest in oocytes of primary follicles. ZP2 was not expressed in granulosa cells of any follicles.

The reproductive significance of human Fallopian tube cilia

Effective tubal transport of ova, sperm and embryos is a prerequisite for successful spontaneous pregnancy. Although there is much yet to be discovered about the mechanisms involved, it is evident that tubal transit is a far more complicated process than initially thought. Propulsion of gametes and embryos is achieved by complex interaction between muscle contractions, ciliary activity and the flow of tubal secretions. Evidence is accumulating of the important and possibly pre-eminent role of ciliary motion in this process; and this review describes current knowledge about ciliary activity and its physiological regulation. There is also a description of the effects on ciliary function of cigarette smoking and various pathological states, including endometriosis and microbial infection, with consideration given as to how altered ciliary activity may impact upon fertility.

Relationship between changes in volume of the oviductal fluid in the ampulla and the descent of ovulated eggs from the ampulla to the isthmus in mice

Follicular growth and ovulation were induced in mice by administration of pregnant mare serum gonadotrophin (PMSG) followed 2 days later by human chorionic gonadotrophin; the day of PMSG injection was designated as day 0. The volume of the ampulla was measured and the location of the ovulated eggs determined at 06:00, 10:00, 14:00, 18:00 and 22:00 on day 3, and at 02:00 and 06:00 on day 4. The volume of the ampulla and hence oviductal fluid, peaked at 14:00 on day 3 and then declined. In all oviduct samples taken up to 14:00 on day 3, eggs were found exclusively in the ampulla. Thereafter, an increasing number of eggs were observed in the isthmus. Thus, the migration of eggs from the ampulla to the isthmus was concurrent with the decrease in oviductal fluid volume. The peak in the volume of oviductal fluid seen at day 3 is likely to coincide with the opening of the ampullary-isthmic junction of the oviduct.

Aquaporin-1 expression in visceral smooth muscle cells of female rat reproductive tract

The aquaporins (AQ-s) are a group of intrinsic membrane proteins which facilitate movement of water across cell membranes; their recent identification in the kidney has led to the reappraisal of the mechanisms and pathways of water movement across epithelia. Aquaporin-1, (CHIP-28) is reported distributed in cardiac myocytes and vascular smooth muscle cells of large arteries. A related protein, AQ-4, has been identified in the sarcolemma of skeletal muscle fibres. We report aquaporin expression in the cell membrane of smooth muscle cells of the rat genital tract; fluorescence immunohistochemistry of rat uterine (fallopian) tube and vagina demonstrated AQ-1 in visceral smooth muscle of these tissues. In the uterine tube, AQ-1 labelling is most pronounced in the innermost longitudinal and the inner cells of the circular muscle layer and is absent from the outer longitudinal muscle layer of the myosalpinx. The possibility of a specific role for AQ-1 in tubal transport by altering the tubal luminal diameter during the estrus cycle is suggested.

Anatomical basis of a passive mechanism for ovum retention at the ampulloisthmic junction

The unexplained behavior of egg retention at the ampulloisthmic junction (AIJ) is a mechanical phenomenon; therefore the key to this process must lie in the anatomy of the oviduct. To investigate the concept that simple anatomical differences between ampulla and isthmus cause AIJ retention, we quantified, in these two regions of the rabbit oviduct, the structural characteristics of the tubal wall that show marked differences: wall thickness and luminal caliber. The oviductal wall greatly increases in thickness and decreases in luminal caliber abruptly at the transition from ampulla to isthmus. These passive mechanical factors predict a dramatically reduced distensibility of the isthmic wall compared to that of the ampulla, and these factors provide us with a simple model to account for the apparent sphincteric activity of the AIJ. Actual measurements of tubal distensibility confirmed our prediction. In addition, egg transport studies following microsurgical removal of the AIJ showed normal transport, an indication that no special structure need exist at the AIJ. We conclude that the contrasting morphology of the ampulla and isthmus may suffice to explain AIJ retention, and no special active mechanism need be postulated.

Some aspects of biomedical engineering research in New Delhi

Biomedical engineering has been recognized in India for the last decade. Technological developments have been in areas of importance to the country, with several groups actively involved in the promotion of bioengineering, particularly in New Delhi. A group at the National Physical Laboratory has contributed significantly to the field of ultrasonics as well as to the development of piezoelectric transducers for other biomedical uses. The Centre for Biomedical Engineering of the Indian Institute of Technology and the All India Institute of Medical Sciences is one of the country's leading centres producing outstanding work in areas like instrumentation, rehabilitation, biomaterials, modelling and analysis. Research in technology applied to reproductive physiology (an area especially relevant to India's needs) was initiated at this centre. Research at the School of Environmental Sciences, Jawaharlal Nehru University has elucidated the effects and mechanisms of the action of low-energy electromagnetic radiation and ultrasound on biological systems--in one of the school's projects the use of bone material for ultrasonic transducers and optical detectors was successfully demonstrated. A selected list of publications shows the wide spectrum of research carried out at these institutions.