Changes

* 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 oestrous cycle, plasma oestrogen exerts a negative feedback inhibition on gonadotrophin secretion.  

* During early-mid follicular phase of the [[Female_Reproductive_Tract_-Oestrous_Cycle_-_Anatomy_%26_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 oestrous cycle, one follicle willl become dominant and it becomes the major producer of oestrogen.

* During later stages of the follicular phase of the [[Female_Reproductive_Tract_-Oestrous_Cycle_-_Anatomy_%26_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.

* When plasma concentrations rise above the threshold value, it acts to enhance gonadotrophin secretion by positive feedback.

* When plasma concentrations rise above the threshold value, it acts to enhance gonadotrophin secretion by positive feedback.

* The high level of oestrogen causes the LH surge that leads to ovulation.

* The high level of oestrogen causes the LH surge that leads to ovulation.