I'm not entirely sure and this response is late but I'm pretty sure it's when the central vacuoles lose their water and can no longer support the cell. When the vacuole of a cell is full it pushes outward against the cell wall. When it has nothing in it, you can assume that because the vacuole is so big and is such a big component of this that this would be the answer.
The vascular cambium produces secondary phloem and xylem tissue.
<span>Vascular cambium, a plant tissue located between the xylem and the phloem in
the stem of a vascular plant. It is also the source of both secondary xylem growth
and the secondary phloem growth. Vascular
cambium is usually found on dicots and gymnosperms not on monocots which
usually lack secondary growth. It does not transport water, dissolved food or
minerals by plants. </span>
<span>Vascular cambia are cylinders of unspecialized meristem cells which
divide to make new cells which
specialize to form secondary vascular tissues.</span>
Answer: The higher levels of estrogen may promote the midcycle LH surge, which is what urine OPKs look for. If this happens, the surge might come a couple of days earlier. This is called positive feedback. On the other hand, the higher estrogen levels my inhibit LH (this is called negative feedback) delaying the surge.
More Helpful Information: It is hard to predict. The higher levels of estrogen may promote the midcycle LH surge, which is what urine OPKs look for. If this happens, the surge might come to a couple of days earlier. This is called positive feedback. On the other hand, the higher estrogen levels my inhibit LH, delaying the surge. You will need to test for ovulation to find out.
