Let’s talk a little bit more about puberty. So before we discuss puberty, let’s discuss
the hypothalamic-pituitary axis. In this case, we’re referring to the HPO
or the hypothalamic-pituitary-ovarian axis. First, there is input from the environment
into that axis which goes into the central nervous system which then feeds into the hypothalamus
which via GnRH or gonadotropin releasing hormone feeds into the anterior pituitary.
The anterior pituitary produces FSH and LH, FSH standing for follicle stimulating hormone
and LH standing for luteinizing hormone which then feeds into the ovary. The ovary then responds
with sex steroid hormone formation which feeds into the uterus. The estrogen causes the endometrial
lining to be formed. Then the estrogen from the ovary feeds back into the hypothalamus
as well as progesterone feeding back into the hypothalamus and the anterior pituitary.
The uterus then, if it’s intact, will cause a menstrual cycle to occur. This entire system has to be intact
for normal pubertal development to occur. It all culminates in the menses.
So remember, you should remember that the menses is a vital sign in a young girl.
If one of these systems are not functioning, she will not menstruate normally.
Let’s talk about now pubertal milestones. So, let’s talk about thelarche or the development of breasts.
This is very high yield because there are lots of questions that can pertain to this subject.
When you’re about 10 ½ years old, you start to make breast buds. Oftentimes, this is confused
with some type of pathology but they are hard upon examination. Then you might start to have pubic hair.
Then you have maximal growth around 11 years old. Then you have menarche which is the onset of menses.
Finally, you have adult pubic hair close to 14 years of age. Now, these ages are based on healthy children.
However, children who have other medical problems may not meet these milestones.
Again finally, you have adult breast contour by 14 ½, close to 15 years old.
Now that we’ve discussed some normal milestones, let’s talk about the first signs of puberty.
First, you have acceleration of growth followed by thelarche or breast budding,
pubarche (appearance of pubic hair), and menarche (menses). It typically happens in that order.
Menarche should never be the first sign. That should alert the clinician that something is amiss.
Let’s just now review the different stages of thelarche. This is a system called Tanner staging,
Tanner stage 1, 2, 3, 4, and 5. There is no zero. With Tanner stage 1, you’ll see here
that the Tanner stage 1 patient is prepubertal. There is no breast development.
At Tanner stage 2, there is a breast bud which again feels hard upon palpation
and can often be confused with pathology. Tanner stage 3, you see that there is a breast elevation.
Tanner stage 4, you see that there is areolar mound while Tanner stage 5 is a normal adult contour.
Again, review this before your test. This may be a question and this could be very high yield.
First signs of puberty, let’s talk about pubarche now. Again, we use Tanner staging here.
Tanner stage 1 is prepubertal while Tanner stage 2 is presexual hair. You may have some hair.
But in Tanner stage 3, you develop even more pubertal hair. In Tanner stage 4,
here you’ll see a mid-escutcheon. That develops into a Tanner stage 5 which is adult female escutcheon.
On average, menarche occurs 2.6 years after the onset of puberty. Again, you may start to see some signs.
Not all girls will achieve Tanner staging at the very same time. So, let’s review.
Remember, female sexual determination is not a default. It’s actually genetically determined
and upregulation of certain genes have to occur. Remember that the paramesonephric development
happens in the absence of AMH or anti-Müllerian hormone which is made by the Sertoli cells
in the male system. Germ cells migrate to the gonadal ridge and invade the gonads
taking cues from somatic cells. The impetus for puberty is not known.
Thank you for listening and good luck on your test.