Ultrastructure of the human periovulatory cervical mucus

Cerić, Francisco; Silva, Doris; Vigil, Pilar

doi:10.1093/jmicro/dfh106

Cited by 39 publications

(38 citation statements)

References 35 publications

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“…Electron microscopy of human cervical mucus has produced a wide range of pore size estimates depending on the methods used, from approximately 100 nm by using SEM (10) or DMSO-mediated glutaraldehyde fixation and transmission electron microscopy (TEM) (8), to 500-800 nm by using freeze substitution and TEM (11), and even 1,000-10,000 nm or larger by using various conventional EM procedures (12)(13)(14).…”

mentioning

confidence: 99%

Nanoparticles reveal that human cervicovaginal mucus is riddled with pores larger than viruses

Lai

Wang²,

Hida³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

337

343

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The mechanisms by which mucus helps prevent viruses from infecting mucosal surfaces are not well understood. We engineered non-mucoadhesive nanoparticles of various sizes and used them as probes to determine the spacing between mucin fibers (pore sizes) in fresh undiluted human cervicovaginal mucus (CVM) obtained from volunteers with healthy vaginal microflora. We found that most pores in CVM have diameters significantly larger than human viruses (average pore size 340 ± 70 nm; range approximately 50–1800 nm). This mesh structure is substantially more open than the 15–100-nm spacing expected assuming mucus consists primarily of a random array of individual mucin fibers. Addition of a nonionic detergent to CVM caused the average pore size to decrease to 130 ± 50 nm. This suggests hydrophobic interactions between lipid-coated “naked” protein regions on mucins normally cause mucin fibers to self-condense and/or bundle with other fibers, creating mucin “cables” at least three times thicker than individual mucin fibers. Although the native mesh structure is not tight enough to trap most viruses, we found that herpes simplex virus (approximately 180 nm) was strongly trapped in CVM, moving at least 8,000-fold slower than non-mucoadhesive 200-nm nanoparticles. This work provides an accurate measurement of the pore structure of fresh, hydrated ex vivo CVM and demonstrates that mucoadhesion, rather than steric obstruction, may be a critical protective mechanism against a major sexually transmitted virus and perhaps other viruses.

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mentioning

confidence: 99%

Nanoparticles reveal that human cervicovaginal mucus is riddled with pores larger than viruses

Lai

Wang²,

Hida³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

337

343

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“…Considering the current evidence and what has been mentioned, it is probable that the changes in hormonal levels that occur in vivo in the reproductive tract of the female of each species during the reproductive cycle subtly regulate the AR, retarding the onset or favouring its timely occurrence. As regards this delicate hormonal modulation that AR could be subject to, it is necessary to mention again the case of steroid hormones, about which more information is available: in the cervix, the oestradiol present in the periovulatory cervical mucus could be exerting the role of AR inhibitor since its onset in such regions of the female reproductive tract would not make fertilisation possible (Ceric et al, 2005;Vigil et al, 2008;Vigil et al, 2009b). On the contrary, in the distal third of the Fallopian tube, there are high levels of progesterone coming from the follicular fl uid, which could promote AR precisely when the spermatozoon and the oocyte are close to encounter, favouring successful fertilisation (Morales et al, 1992;Vigil et al, 2008;Vigil et al, 2009c).…”

Section: Discussionmentioning

confidence: 99%

“…In the physiological context of fertilisation, the spermatozoa have to migrate through the cervical mucus . This biological fl uid, found in some mammals, such as rabbits, ruminants and primates, possesses rheological properties subject to endocrine regulation, and these characteristics change in physiological and pathophysiological conditions (Vigil et al, 1991;Vigil et al, 1995;Ceric et al, 2005;Vigil et al, 2009a). After passing through the cervical mucus and endometrial cavity, the spermatozoa in the Fallopian tube come in contact with the follicular fl uid.…”

Section: Oestradiolmentioning

confidence: 99%

Modulation of spermatozoon acrosome reaction

Vigil¹,

Orellana²,

Cortés³

2011

Biol. Res.

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Spermatozoon acrosome reaction is an exocytotic event of the utmost importance for the development of mammalian fertilisation. Current evidence shows that the triggering of the acrosome reaction (AR) could be regulated by the action of diverse compounds, namely, metabolites, neurotransmitters and hormones. The aim of the present review is to describe the modulating effects of several compounds that have been classifi ed as inductors or inhibitors of acrosome reaction. Among AR inductors, it is necessary to mention progesterone, angiotensin II, atrial natriuretic peptide, cathecolamines, insulin, leptin, relaxin and other hormones. Regarding the inhibitors, oestradiol and epidermal growth factor are among the substances that retard AR. It is worth mentioning that gamma-aminobutyric acid, a neurotransmitter known to be an inhibitor in the central nervous system, has been shown to induce AR. The multiple hormones located in the fl uids of the female reproductive tract are also likely to act as subtle regulators of AR, constituting a fundamental aspect for the development of successful fertilisation. Finally, it is necessary to emphasise that the study of regulation exerted by hormones and other compounds on AR is essential for further understanding of mammalian reproductive biology, especially spermatozoon physiology.

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“…Additionally, findings from the present study suggest that the sexual hormones may influence the changes in salivary flow rate and pH during ovulation phase. Electrolyte level, pH, buffer capacity, flow rate and ultra structure have been studied in saliva in reference to several diseases and physiological conditions (26)(27)(28)(29)(30)33,(36)(37)(38)(39)(40)(41)(42). The present study revealed the difference in the electrolytes, pH, buffer capacity and flow rate of saliva during the ovulation phase.…”

Section: Discussionmentioning

confidence: 61%