system
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human
What causes the surge in luteinizing hormone just prior to ovulation?

I have read a few physiology textbooks that were published a few years ago, and I have not gotten anything concrete.  


I read from the 9th edition (latest) of Sherwood Physiology, which states that there are two sets of kiss1 neurons in the hypothalamus. According to the text, negative feedback involves **low** concentrations of estrogen **inhibiting** the kiss1 neurons in the arcuate nucleus whereas positive feedback involves **high** concentrations of estrogen **stimulating** the kiss1 neurons in the anteroventral periventricular nucleus. Kiss1 neurons secrete kisspeptin, which act on GnRH-secreting cells in the hypothalamus.  


However, the 13th edition (latest) of Guyton-Hall says that "the cause of this abrupt surge in LH secretion is not known". It states two possible explanations. The first one is the one that Sherwood gives - about how estrogen has a "peculiar positive feedback effect" of stimulating pituitary secretion of LH, which is in "sharp contrast to the normal negative feedback effect of estrogen that occurs during the remainder of the female monthly cycle." The second explanation Guyton-Hall suggests is that the granulosa cells begin to secrete a small but increasing amounts of progesterone a day or so before the LH surge, and it has been suggested that this secretion might be the factor that stimulates the excess Lh secretion.  


My main question is: since the publication of these textbooks, have we learnt anything new or is this still something that we are not sure of?  
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edit1: Added some info for clarification.
gpt
LH is released from the pituitary gland. In women, the LH surge causes the ovarian follicle to tear and release a mature egg (oocyte). Prior to ovulation the increase of estrogen causes the increase in LH which triggers ovulation.