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Vital Role of Egg & Sperm

When setting out on your Journey to Conceive it really helps to have an understanding of the Female and Male reproductive anatomy.

The Sperm

The sperm are formed in the Testes.  The Epididymis is a coiled structure on top of the testes which receives the immature sperm from the testes and stores it for several days.   In the release process the penis fills with blood and becomes erect with continual stimulation causing an ejaculation.

During the ejaculation smooth muscle contractions will propel the sperm move from the Epididymis into the Vas Deferans Duct and then the Seminal Vesicle and Prostate where the sperm is provided with fluids (Semen) that contain and nourish the sperm.  Then the Semen passes down the urethra to be expelled out of the end of the penis.

The Semen fluid is designed to help sperm stay alive once they enter the vagina and include:

  • Fructose that provides energy
  • Prostaglandins (hormone like substances) to help prevent the vagina seeing the sperm as an invader
  • Alkaline Fluid which helps keep sperm alive longer in the vagina which is Acidic
  • Clotting Factors which help the sperm live for longer

The Follicles and their Eggs

A female has 2 Ovaries and 2 Fallopian tubes.

Each Ovary contains eggs which are contained within sacs called Follicles.

In each menstrual cycle one Follicle in either Ovary will Mature (grow) enough to reach a size of about 16-22mmhg and when it reaches this size it will rupture and release its egg (Ovulation) into the Fallopian tube the Ovary is connected to.   Over several days it will move along the Fallopian Tube facilitated by gentle muscle contractions.

Successful Fertilisation & Implantation

If the Egg hopefully fertilises with 1 of the sperm during its journey down the Fallopian tube then there is a chance that it will go through the different steps to become a Blastocyst when reaches the uterus and hopefully will implant (bury itself) into the lining of your uterus.  If this happens it will your HCg hormone levels will rise leading to a Positive Pregnancy Test 2 weeks after Fertilisation.

Unsuccessful Fertilisation

If the Egg does not manage to fertilise with any of the sperm on its journey down the Fallopian tube then it will be expelled from your body in the next Menstrual Cycle.

When Does It Not Happen As Above?

No Egg Released

Some Follicles do not contain eggs.  One reason you may not become pregnant during one menstrual cycle is if the Follicle that matured to the right size to rupture did not contain an egg meaning no egg available for the sperm to Fertilise.

Multiple Eggs Released with Natural Conception

With Natural Conception there is a chance that more than one Follicle matures releasing more than 1 egg and if they all fertilise can lead to Pregnancies with Multiples.

Multiple Eggs Released with Natural Conception & Fertility Follicle Stimulating Medications

Some people under the care of a Fertility Specialist are given Follicle Inducing Medications through tablet form or injection that stimulate more than 1 Follicle to mature with potential to release more than 1 Egg and if all released Eggs fertilise can lead to Pregnancies of Multiples.

Which Scenarios can Happen to Create Multiples

Non-Identical Twins 

2 Follicles may mature in 1 Ovary and release with potential to be Fertilised

1 Follicle may mature in each of the 2 Ovaries and be released with potential to be Fertilised

Non-Identical Triplets

3 Follicles may mature in 1 Ovary and be released with all Fertilising

2 Follicles may mature in 1 Ovary and 1 Follicle may mature in the other Ovary then be released with all Fertilising

Non-Identical Versus Identical Multiples

Non Identical Twins also known as Dizygotic means that there are 2 or 3 separate Eggs that fertilise each with a different sperm with their own individual chromosomes (genes) and no more alike than typical brothers and sisters.   In this scenario there can be just girls, just boys or a mix.

Identical Twins (2) also known as Monozygotic means that one egg is fertilised by one sperm and then splits into 2 or 3 creating identical babies with the same chromosomes (genes), features and sex.  They may or may not share a placenta & or amniotic sac.  Characteristics such as their size and personality are non-genetic so they may be different.

Triplets can be Identical, Non-Identical or a Combination – for example you can have a set of triplets where 2 are identical and one is not

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