The uterus is the organ where the fetus gets implanted and develops. It is connected to the vagina through the cervix. The cervix, as such isn’t an organ but simply a part of the uterus specifically at its lower end. It is of great importance in the childbirth and fertility in females. To understand this, let’s begin our journey to uncover the structure and function of the cervix.
The inside-out of the cervix:
The cervix is roughly cylindrical and about an inch long. As mentioned earlier, it is continuous with the uterus and opens into the vagina. So, it consists of the following structures:
- Ectocervix – The lower part continuous with the vagina
- Endocervical canal – A central canal that runs along the lining of the uterus connecting it with the vagina
- Internal os – The narrow opening at the neck of the uterus
- External os – The narrow opening at the lower end through which menstrual blood flows into the vagina. It also separates the ectocervix and the endocervix.
- Transformation zone – Area of changing cells where abnormal cells most likely develop during cancer
Blood supply and drainage occur through the uterine artery and uterine vein. So, are there any special cells in the cervix? Well, the endocervix is lined with mucus-secreting cells. This mucosa also covers the ectocervix to form the exocervix.
Functions of the cervix:
The main function is associated with mucus production. But, how is it connected? Simply put, the mucus production changes the texture of the cervix. This, in turn, alters the function at different periods as shown below:
- During the times of ovulation, the estrogen levels are high. This causes the mucus to become thin and serous. So the sperm easily enters the uterus and chances of pregnancy are high.
- After ovulation, the mucus becomes thick due to the effects of progesterone. This inhibits the passage of sperm into the uterus.
- Another function of this thick mucus is to maintain pregnancy and prevent the pathogens from harming the growing fetus. And this is called the cervical mucus plug.
The cervix is also involved in childbirth. Dilatation and shortening of the cervix are essential for the labor to progress smoothly. Lastly, the cervix also maintains the sterility of the upper female reproductive tract. This protects the uterine cavity from bacterial invasions under normal conditions also.