Page 79 - The Cell in 40 Topics

very four weeks, a healthy woman's body makes broad
preparations in order for an egg to be capable of fertilization.
Once again, hormones effect the main elements of those
preparations.
At the very beginning of this four-week period, the woman's pituitary
gland produces LH. After setting out from its origin in the brain, this hor-
mone travels a considerable distance through the bloodstream before
reaching the ovaries. Hormones are exceptionally minute molecules, and
for them, movement through the human body represents a journey equiva-
lent to many kilometers. However, every LH hormone reaches the ovary
directly, never getting lost, with full apparent knowledge of its destination,
and without being diverted toward any other organ. LH's arrival signals
that it's now time for the ovaries to go into action (Figure 63).
Each ovary contains thousands of immature egg cells. Under the in-
fluence of the LH arriving from the pituitary gland—which possesses a
special formula to set these cells in action (Figure 64)—a few of them begin
to mature. There are a great many substances in the blood, yet apart from
LH, none of these possesses the ability to activate ovulation. In other

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