Ovarian follicles are small sacs filled with fluid & and developing eggs that are found inside a woman’s ovaries. They secrete hormones that influence various stages of the menstrual cycle. At the time of puberty, women have approximately 200,000 to 300,000 eggs, each with the potential to ovulate.There is one egg or oocyte per follicle. In a normal menstrual cycle, one follicle will grow that contains one egg.
Follicles are small sacs of fluid found in the layers of the ovaries, these contain immature eggs (oocytes). When the follicle has grown to the right size, it ruptures and releases a mature egg ready to be fertilized.
A large number of primary follicles degenerate during the phase from birth to puberty. Therefore, at puberty, each ovary has about 60,000-80,000 primary follicles, which are formed by the division of the primitive cells called the germ cells. Read more about getting pregnant with one follicle.
Can You Get Pregnant With One Follicle?: Complete Guide
Role of ovarian follicles
Normally, the ovaries in humans make one important follicle that leads to one egg being released during each monthly cycle. In this process, this special follicle has to go through all the necessary stages on time.
Folliculogenesis is the process of ovarian follicle formation & and maturation. The stages of follicular development are from the
- Primary follicle
- Secondary follicle
- Tertiary follicle
- To the Graafian follicle which is the final stage of maturation for the eggs.
Ovulation is the process in which a mature egg is released from the ovary. After it is released, the egg moves down the fallopian tube and stays there for 12 to 24 hours, where it meets the sperm & and undergoes fertilization.
Prior to ovulation, the average diameter of the dominant follicle varies between 17 to 24 mm (range 17-36 mm).
Ovulation is a physiologic process defined by the rupture and release of the dominant follicle from the ovary into the fallopian tube where it has the potential to be fertilized. A dominant ovarian follicle refers to the follicle that enlarges to release an ovum during a menstrual cycle. Usually, approximately 10 Graafian follicles begin to mature where one becomes a dominant follicle and the rest degenerate.
As the dominant follicle matures, so does the egg inside that will eventually be released when you ovulate. The dominant follicle releases more estrogen which thickens the uterine lining so that a fertilized egg (embryo) can implant.
Ovarian follicles are small sacs in the ovaries that contain immature eggs. Monitoring them helps gauge how many eggs an individual may have in reserve. This can indicate the chances of success with fertility treatment.
Can you get pregnant with only one mature follicle?
In case you’re trying to have a baby naturally, you can get pregnant as long as your body is still capable of releasing a mature egg from the follicle, which can then meet with sperm in the fallopian tube.
Single follicle pregnancies are not an exception but rather the norm for women undergoing natural, non-assisted reproductive cycles, it takes just one egg to get pregnant.
If you’re using intrauterine insemination –IUI & and are less than 40 years old, having one or two mature follicles is preferred. Having more than that may not increase your chances of getting pregnant.
The age of the woman plays a very important role in determining the success of IUI. Under the age of 35, the chances of success of intrauterine insemination is around 20%. Above the age of 35 but under 40, the chances decrease to 10%. After that, the chances of getting pregnant reduce to 2-5%.
Read more: 6 Symptoms Of IUI Pregnancy
Ovulation is the monthly process whereby the female reproductive system produces a mature egg. During ovulation, the brain’s pituitary gland releases two hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Together, these hormones are known as gonadotropins.
Any number of conditions can hamper the body’s ability to ovulate effectively. One of the primary ways to address this challenge is with medications that stimulate the ovarian follicles to produce multiple eggs in one cycle. The two most common fertility medications used to promote ovulation include Clomiphene Citrate (Clomid or Serophene) and Gonadotrophins.
Apart from the number of follicles, it’s also important to assess follicle size, as this is an indication of the maturity of the egg in the follicle. In a fertility cycle, the ideal size is between 18 and 22 millimeters in diameter.
Development stages of ovarian follicles
Folliculogenesis is the developmental process of ovarian follicles starting from a reserve of quiescent primordial follicles set up in early life and ending with either ovulation or follicular death by degeneration.
The different stages of ovarian follicles are:
Primordial follicle: They are the first class of follicles formed in mammalian ovaries and consist of an oocyte surrounded by a single layer of flattened granulosa cells. These follicles remain in a dormant state until they receive signals for activation or are relieved of a negative regulatory factor.
Primary follicle: It is defined by the presence of one or more cuboidal granulosa cells that are arranged in a single layer surrounding the oocyte
Secondary follicle: The secondary follicles look very similar to primary follicles, except that they are larger, there are more follicular cells, and there are small accumulations of fluid in the intracellular spaces called follicular fluid (nutritive fluid for the oocyte). These gradually join together to form an antral follicle.
Antral follicle: They are small follicles (about 2-9 mm in diameter) that we can see – and measure and count – with ultrasound. Antral follicles are also referred to as resting follicles. Vaginal ultrasound is the best way to accurately assess and count these small structures.
Follicle & Fertility
Ovarian follicles are small sacs filled with fluid that are found inside a woman’s ovaries. They secrete hormones which influence stages of the menstrual cycle and women begin puberty with about 300,000 to 400,000 of them. Each has the potential to release an egg for fertilisation. Follicles and their size and status are a vital part of assessing fertility and fertility treatment.
An evaluation of follicles involves a pelvic ultrasound scan of uterus and ovaries as well as blood test for Anti-Mullerian Hormone (AMH). The pelvic ultrasound scan will assess the size and number of follicles present on the ovaries called an Antral Follicle Count. The results of this scan as well as blood test will allow a fertility specialist to assess fertility and therefore your ability to conceive.
How to increase ovarian follicle count?
Ovarian follicle count does not increase. Follicles can be made healthy by: eating a healthy diet, avoiding smoking, maintaining a healthy body weight, avoiding stress, improving your blood flow and taking fertility supplements.
What do ovarian follicles secrete?
Ovarian follicles synthesize and secrete steroid hormones that play essential roles in the female. These are estrogens, progestins, and androgens.
How many immature follicles indicate PCOS?
Polycystic ovaries (PCO) are described on ultrasound scan as the presence of 12 or more follicles in each ovary measuring 2-9 mm in diameter, and/or increased ovarian volume of one ovary >10 ml.
Can you get pregnant if you have no follicles?
You can’t get pregnant if you are not ovulating because there is no egg for the sperm to fertilize.
Will all follicles release an egg?
Usually, yes. In most cases follicles will release an egg. Sometimes an egg may be absent.
What is the Antral Follicle Count (AFC) at 20 to 30 & at 35 to 40 years of age?
On average, women in their mid-20s to early 30s have around 12 to 30 antral follicles; while women aged, 35 to 40 may have between 8 and 15
What happens to my follicles during IVF?
During IVF, your ovaries are stimulated to make the follicles grow and produce mature eggs. Ultrasound scans will tell us when your follicles have grown to the right size, and how many follicles have grown.
Can my follicles be affected by IVF?
Ovarian Hyperstimulation Syndrome may occur if the ovaries are very sensitive to stimulation and produce an unusually large number of follicles and therefore eggs (usually more than 15) or in the presence of high levels of oestradiol.
Can I have twins with one follicle?
It’s rare, but not impossible. If the single released egg splits into two after being fertilized, it can result in identical twins resulting in monogenic twin pregnancies.
Does the number of follicles determine my fertility?
If you have lots of follicles, then you have the potential to release more eggs increasing the chance that one of those eggs will be healthy enough to result in a successful pregnancy. Egg quality is determined by your age and also your lifestyle.
Can IVF help if I have only one follicle?
One follicle is enough for pregnancy, but if you have trouble conceiving, then getting the right medical advice on increasing your follicular count might help.
Is there a way to predict how many follicles I will produce in a cycle?
Antral follicle (AFC) counts & Anti-Mullerian Hormone (AMH) are good predictors of the number of mature follicles that we will be able to stimulate in the woman’s ovaries when we give injectable hormones medications that are used for in vitro fertilization.
Can a follicle release more than one egg?
There is usually one egg per follicle; In a normal menstrual cycle one follicle will grow that contains one egg.
Does age affect the number of follicles?
As a woman ages, her fecundity declines because of the loss of follicles from the ovary and an associated reduction in oocyte quality. Advancing age decreases the number of follicles.
Read more: Bulky Uterus: Symptoms, Causes and Treatment