The mammary gland is a modified apocrine
sweat gland. In fact, it really is a number
of glands, individual apocrine sweat glands.
You see two sections here of the non-lactating
mammary gland. On the left hand picture, it’s
taken at low magnification. And you can just make
out some dense connective tissue, some adipose
tissue, and then tiny little profiles of what
are terminal ductals, small ducts that remain
in a non-lactating breast. And these terminal
ducts are shown at higher magnification on the
right-hand side of the slide. These terminal
ducts under the influence of prolactin, progesterones,
and estrogens during pregnancy, are going
to develop into the secretory units of the
modified sweat gland, the apocrine sweat gland.
They are going to proliferate and form lobules,
acini, secretory units. And then within those
secretory units, there’s going to be an
intralobular duct that then carries the secretion
product towards the nipple where it joins
the lactiferous duct. And then the milk is
then secreted from that lactiferous duct.
And just prior to the exit of the duct in the
nipple, there is a little structure out-pocketing called
the lactiferous sinus. On this section now
low power, you start to see a number of lobules forming.
These are individual modified apocrine
sweat glands, each with their own duct system,
each then opening in through the lactiferous
ducts out into the nipple. And under high
magnification on the right-hand side, you
can see some details of each lobule. And all
those secretory units evident there are really
just growth of these terminal ducts that remain
in a non-lactating breast that have gone through
this growth and transformation into secretory
units under the influence of various hormones.
So, in summary, I think it’s important to
understand the importance of the uterine tube
being both a transport organ for sperm and
the oocyte, possibly to bring them together
for fertilization. And also the epithelial
cells provide nutrition to the environment
for those oocytes and sperm and for the fertilized
egg. Also, there is this muscular layer around
the uterine tube that aids that transport
besides the ciliated epithelial cells.
The endometrium undergoes drastic changes under
the influence of estrogen and progesterone.
Estrogen repairs the lost functional layer
of the endometrium after menstruation, and
progesterone then stimulates the repaired
glandular tissue to start secreting glycogen
and other nutrients that are important for
the possible implantation of a fertilized
egg or a blastocyst. And these changes are
all designed to optimize that possibility.
The cervix optimizes transport of the sperm
because the secretory cells secrete a watery
mucous at the time of ovulation, whereas,
at other times the mucous is very thick
and viscous and it is a retaliation for transport
of any bacteria and pathogens, and even sperm.
And the vagina is a protective environment because
of the acidity of the lumen produced by the
action of bacteria on glycogen produced by
the epithelial cells, and it has a wear and
tear epithelium because it’s the female
copulatory organ. And lastly, the mammary gland
is a modified sweat gland. It undergoes dramatic
changes during pregnancy, and also during
lactation. So thank you for listening to this
lecture. I hope you’ve now learned a lot
about the organs of the female reproductive
system. And I hope you now can appreciate
how important it is that all these organs
act together in unison under the influence
of hormones they produce, but also hormones
that are produced by the pituitary gland.