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Birla Fertility & IVF
Birla Fertility & IVF
Ovarian follicles Ovarian follicles

Ovarian Follicles: What are they

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Understanding of ovarian follicles

The ovarian follicle is a fluid-filled sac in the ovaries of the female reproductive system which contains an immature egg. During a woman’s menstrual cycle, around the time of ovulation, an egg is matured, and the follicle breaks open and releases that egg from the ovary for possible fertilisation. Though numerous follicles begin to develop in each cycle, only one will usually ovulate an egg, more than one may increase the chances of twins. After the ovulation phase, the follicle is turned into a corpus luteum.

A fertility expert may check ovarian follicles to diagnose and treat any signs of infertility.

Stages of ovarian follicle development

Ovarian follicle development is divided into two stages:-

Preantral phase

  1. Formation and beginning of growth 
  2. Activation of primordial follicles 
  3. Growth of primary follicles
  4. Growth of secondary follicles

Antral phase

  1. Tertiary follicle 
  2. Graafian follicle (Preovulatory)

Normal ovarian follicle size

A normal ovary has around 8-10 follicles which vary from 2mm to 28 mm in size. Antral follicles are the ones that are smaller than 18 mm in diameter, while dominant follicles are the ones that are between 18 and 28 mm in diameter. When ready to ovulate, a developed follicle measures 18-28mm in diameter.



Is it possible to get pregnant with multi follicular ovaries?

Yes, you can get pregnant with multi follicular ovaries, but there are chances that the conception process may slow down.

How many follicles are developed each month?

Every month, 1 follicle is selected, and when it is matured and developed to the right size, it ruptures and releases the egg for the fertilisation process.

How do follicles develop?

The pituitary gland produces two hormones, follicle-stimulating hormone (FSH) and luteinising hormone (LH), which cause primordial follicles to mature.

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