Changes

==Introduction==

==Introduction==

The follicle is the functional unit of the ovary containing both gametes (Oocyte) and endocrine cells (Granulosa and Theca cells). A female is born with all the primordial follicles it is ever going to have i.e Primordial Follicles do not divide anymore, they either develop further into primary, secondary, and tertiary follicles or they degenerate. Therefore the number of follicles declines with age as follicles develop and degenerate during the [[Female_Reproductive_Tract_-Oestrous_Cycle_- Anatomy & Physiology|oestrus cycle]]. When the supply of follicles is depleted then reproductive senescence occurs. In humans this phenomenon is known as "The Menopause".  Prior to ovulation, [[The_Ovary_-_Oogenesis_- Anatomy & Physiology|oogenesis]] and hormone production both occur in the follicle. The process of follicular growth is known as '''Folliculogenesis'''.

The follicle is the functional unit of the ovary containing both gametes (Oocyte) and endocrine cells (Granulosa and Theca cells). A female is born with all the primordial follicles it is ever going to have i.e Primordial Follicles do not divide anymore, they either develop further into primary, secondary, and tertiary follicles or they degenerate. Therefore the number of follicles declines with age as follicles develop and degenerate during the [[Oestrous Cycle - Anatomy & Physiology|oestrus cycle]]. When the supply of follicles is depleted then reproductive senescence occurs. In humans this phenomenon is known as "The Menopause".  Prior to ovulation, [[The_Ovary_-_Oogenesis_- Anatomy & Physiology|oogenesis]] and hormone production both occur in the follicle. The process of follicular growth is known as '''Folliculogenesis'''.

==General Structure==

==General Structure==

* Initially, FSH acts on granulosa cells to induce synthesis of oestrogens.

* Initially, FSH acts on granulosa cells to induce synthesis of oestrogens.

* Oestrogen has a paracrine action within the ovary to induce the proliferation of granulosa cells.

* Oestrogen has a paracrine action within the ovary to induce the proliferation of granulosa cells.

* During early-mid follicular phase of the [[Female_Reproductive_Tract_-Oestrous_Cycle_- Anatomy & Physiology|oestrous cycle]], plasma oestrogen exerts a negative feedback inhibition on gonadotrophin secretion.  

* During early-mid follicular phase of the [[Oestrous Cycle - Anatomy & Physiology|oestrous cycle]], plasma oestrogen exerts a negative feedback inhibition on gonadotrophin secretion.  

* As a result of this, FSH levels begin to fall.

* As a result of this, FSH levels begin to fall.

* The inhibiting effect of oestrogen only occurs whilst plasma oestrogen is below a certain threshold value.

* The inhibiting effect of oestrogen only occurs whilst plasma oestrogen is below a certain threshold value.

* During later stages of the follicular phase of the [[Female_Reproductive_Tract_-Oestrous_Cycle_- Anatomy & Physiology|oestrous cycle]], one follicle willl become dominant and it becomes the major producer of oestrogen.

* During later stages of the follicular phase of the [[Oestrous Cycle - Anatomy & Physiology|oestrous cycle]], one follicle willl become dominant and it becomes the major producer of oestrogen.

* Under the influence of oestrogen, granulosa cells which were previously unresponsive to LH, acquire LH-receptors and become responsive to LH.

* Under the influence of oestrogen, granulosa cells which were previously unresponsive to LH, acquire LH-receptors and become responsive to LH.

* The plasma concentration of oestrogen starts to rise.

* The plasma concentration of oestrogen starts to rise.