Hello and welcome to the zero to finals podcast.

My name is Tom and in this episode I'm going to be going through the menstrual cycle.

And you can find written notes on this topic at zero to finals.com slash menstrual cycle

or in the reproductive system section of the zero toals obstetrics and gynecology book.

So let's get straight into it.

The menstrual cycle consists of two phases, the follicular phase and the luteal phase.

The follicular phase is from the start of menstruation to the moment of ovulation, which is the

first 14 days in a 28-day cycle. The luteal phase is from the moment of ovulation to the start

of menstruation, which is the final 14 days of the cycle. Let's start by talking about the follicular phase.

From puberty, the ovaries have a finite number of cells

that have the potential to develop into eggs.

These cells are called oocytes, spelt with two oes.

Granulosis cells surround the oocytes forming structures called follicles.

Follicles go through four key stages of development in the ovaries, the primordial follicles, the primary follicles, the secondary follicles, and the antral follicles,

which are also known as graphian follicles.

The process of primordial follicles maturing into primary and secondary follicles

is occurring continuously independent of the menstrual cycle. Once the follicles reach

the secondary follicle stage, they develop receptors for follicle stimulating hormone or FSAH. Further

development after the secondary follicle stage requires stimulation from follicle stimulating hormone, or FSAH.

At the start of the menstrual cycle, FSAH stimulates further development of the secondary

follicles. As the follicles grow, the granulosis cells that surround them secrete

increasing amounts of estradiol or estrogen.

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