"Using the Zestica lubricant during sexual intercourse helps couples trying to conceive by giving them the assurance that sperm mobility will not be reduced", says Dr Zhao. He also highlighted the fact that "Zestica is made from a natural occurring molecule which provides moisture and is not harmful to sperm, this helps create the best possible environment during sexual intercourse for couples trying to get pregnant."

For women who suffer from dryness, Dr Zhao adds that "Zestica has been formulated containing a special molecule called Hyaluronic Acid. This draws water into the vaginal tissues."

To help combat dryness, you should use Zestica daily for about a week and then reduce usage to two to three times a week, as needed. This should maintain a comfortable vaginal area.

Zestica Fertility Lubricant: the science

Zestica contains the natural ingredient Hyaluronic Acid (HA) with a combination of different molecular weight to sustain its stability in the vaginal acidic environment. HA is a super-water absorbant with natural moisturisation functionality which makes it a fantastic lubricant and extremely safe, due to its natural properties. The formula is clinically proven to be safe to sperm under vaginal environment.

THE ROLE OF HYALURONIC ACID IN REPRODUCTION
(HA in cervical mucus and its interaction with sperm)

The composition and characteristics of cervical mucus change considerably throughout the menstrual cycle (and during pregnancy). Cervical mucus is only receptive to sperm up to 6 days prior to, and approximately 1 day following, ovulation. During the rest of the menstrual cycle cervical mucus is "hostile" to sperm i.e. sperm are unable to penetrate.

The ejaculate consists of spermatozoa and seminal plasma with sperm comprising only 5% of the ejaculate. The seminal plasma contains a myriad of factors which act to provide the sperm with energy and protection whilst in the vagina. In humans, sperm are thought to enter the cervix via cervical mucus relatively quickly after ejaculation (within 1hour). Sperm that remain in the vagina for a long time will die and in order to survive, and progress to the egg, they need to swim and enter the cervical mucus which acts as a comparative haven. Upon entering cervical mucus, they are stripped of their outer coat (which acts to keep them in a suppressed non fertile state) and thus undergo the first stage of activation (termed capacitation). It is unknown how long sperm remain in the cervix in an active state, yet still remain capable of fertilisation, but studies in the laboratory would indicate this can be several days.

The concentration of hyaluronic acid (HA) in the cervix changes throughout pregnancy, and in particular increases during the latter stages of pregnancy where it is thought to play a significant role in cervical ripening (remodelling of the cervix in preparation for birth).

The role of HA in cervical mucus and its subsequent effect on sperm is not well understood. However, HA has been used as a cervical mucus substitute for laboratory sperm function studies for the last 25 years. As such, there is a wealth of information regarding the interaction of HA with sperm. HA has been used as a cervical mucus substitute because its structure and properties are similar. The penetration of sperm into HA is highly correlated with semen characteristics and sperm function testing - to the same degree as with cervical mucus. Additionally, the functional capacity of sperm that have penetrated HA or cervical mucus (motility, capacitation status, fertilising ability) are very similar. Therefore penetration into HA is regarded as a simple and objective means of measuring the functional competence of sperm and is widely used as an effective alternative to human cervical mucus.

HA in the oviduct

Sperm are stored, sometimes for several days, in the oviduct prior to fertilisation. The oviduct acts to maintain sperm in a quiescent but "always primed" state of readiness for the arrival of the egg. How the oviduct does this is unknown but glycosaminoglycans, like HA, play a key role in these processes. Importantly, these glycosaminoglycans, in conjunction with other factors in the oviduct (for example, binding to the oviductal epithelium), act as a final gatekeeper to prepare the sperm by activating key signalling complexes in the sperm so that they are ready to interact with the egg. However, because sperm can remain in the oviduct for several days the oviduct needs to achieve an important balance in not over-stimulating the sperm, otherwise they would not be able to fertilise eggs.

HA in the Cumulus Oophorus.

HA is a major and relatively well studied component of the cumulus oophorus (i.e. cumulus) providing viscoelastic properties for the cumulus structures. The cumulus is a series of layers - comprised usually of several hundred cells - which surround the human egg, making the egg look like a fluffy ball (Figure1). The cumulus is the first barrier surrounding the egg that the sperm encounter. The sperm must penetrate this before they interact and bind with the zona pellucida. The zona pellucida activates a sac in sperm to explode (the acrosome - red dots in Figure 1) after which the sperm is able to penetrate the zona pellucida and fuse with the egg. HA assists the binding of the cumulus cells together and importantly acts (in coordination with other molecules) to activate the sperm whilst in the cumulus. This activation is thought to be very important. Whilst we do not know the full details it is likely to involve two key processes:

1. Stimulating the sperm cells to change their movement from a slow progressive pattern to a vigorous thrashing movement - hyperactivated motility. They must undertake this transformation so that they can generate the necessary power and thrust to penetrate the cumulus and zona pellucida. Without this change of movement the sperm cannot fertilise.
2. Priming the sperm cell by - for example - increasing the calcium concentration in the cell, so that its acrosome can be activated when required i.e. when it reaches the zona pellucida.

The sperm is not passive in this process and its interaction with the cumulus and, in particular HA, is a very dynamic one. Sperm contain an essential enzyme - hylauronidase - that digests HA. During initial penetration of the cumulus, hylauronidase is released from the sperm which assists the cell in penetration of the cumulus, allowing it to push its way between the cells and reach the zona pellucida.

General information about Hyaluronan

Hyaluronan is the major glycosaminogly present in follicular, oviductal and uterine fluids. It is a unique macromolecule which is found in tissues and body fluids in every mammalian species. As a physiological substance, hyaluronan is rich in the female reproductive tract and also abundant around oocytes, especially during the periovulation period. Following studies in mammalian species, hyaluronan, along with recombinant human albumin, not only support human embryo development during the pre-implantation stages in culture, but also facilitate the implantation of human embryos. It has also been demonstrated that hyaluronan and recombinant human albumin can significantly improve embryo cryosurvivability.

Hyaluronan is present in the reproductive tract and the highest concentration is found in the uterus. Hyaluronan appears to assist in sperm selection during fertilisation, promote embryonic cell proliferation and facilitate embryo implantation.

Zestica Fertility Clinical Testing

Clinical testing conducted at the University of Dundee has proved that Zestica Fertility significantly increases sperm motility and is not harmful to sperm.