Re: Basic anatomy and physiology of the prostate - some questions

Dr. Sancha...Your response was awesome as usual. Thanks so much, and I
loved your comment about the metaphysics :-) . It is great to hear from you
again, and this is a great thread, and "unknown" raised some good points
which you have certainly helped to clarify. I really liked your para 5 on
the capsule (and surgical capsule, versus sheath, etc), and I reread it
several times. I am going to make a "physics" type comment on the growth of
the prostate in response to "unknowns" comments he made earlier in regards
to the apparent misuse of the term capsule, and the outward/inward stuff
that he quoted from the three credible web sites. I get the idea that all
three of those web sites are misusing the word capsule, but I am really not
sure. I believe you refer to the capsule as "the original prostatic
tissue", as you put it.

I look at it this way. First let me say things in nature can grow in
different manners (both in plants and animals). Trees grow from the top up,
whereas grass blades grow from the bottom up. You indicate how the prostate
grows in para 5, and I think I understand it after reading it several times
(ie the dividing cleavage plane, etc).

However, no matter how something grows, I see it as continuously growing
until it sees a resistance. This is simple physics. I think the prostate
does grow in all directions (even if it is the inner "hyperplastic tissue"
pushing the outer "original prostatic tissue" outward - I hope I said that
right). But if you will bear with me, I think "inward" and "outward" tend
to become meaningless in a sense. In other words the growing part (which is
inside the original tissue) will keep expanding in whatever direction it can
until it sees a resistance that will not "expand" or "yield" any more.

Now, how far the original tissue (which I believe is the capsule that the
web sites were referring to) will expand, will determine how much the inner
hyperplastic tissue will start closing off the urethra. So I believe the
hyperplastic tissue does grow in all directions and it keeps pushing outward
as long as it can, until it sees a resistance that wont let it go in that
direction any longer and then it can only push (or grow) inward. I would
also like to note that it seems to me even after it hits a hard resistance,
that it would still try to keep growing outward, and compress tissue in that
area similar to the kidney tumor you mentioned - am I correct?

Sorry about all that, but I was trying to be very clear :-) . I have also
made an in-line comment after your para 1, about surfaces sticking together
after surgery.

Pete



fgomsan@xxxxxxxxx wrote:
Dear Unk,

Too many complex and metaphysical questions for a relatively simple
subject. This urethral lining problem mesmerizes a lot of patients. I
will try to help.

1. prostatic urethral lining.
If you think of the prostatic urethra as the throat of a boy, and of
the prostatic hyperplasia as the tonsils in a boy's throat, you will
quickly understand that removing the hyperplastic tissue works exactly
as removing the tonsils. You have to cut through the epithelial lining
of the prostatic urethra to reach the hyperplastic tissue. When you
finish there is a wound in both cases, there is a surface that needs
to undergo repairs, and the borders of the wound start to grow new
epithelial cells that will eventually cover the wound surface. if you
look inside the boy's throat just after the operation you will see two
wound surfaces, if you look inside the prostatic urethra after TURP or
PVP, there is a 360º wound surface. After tonsillectomy, it is
impossible for those surfaces to stick together, because they are
never in contact. After TURP or PVP it is theoretically possible that
two surfaces in contact could develop adherences, but this is
extremely rare. TURP and PVP cavities usually have a diameter of 2-3
cm, so surfaces do not stick together, and the urine gets between
these surfaces, making it difficult to develop adherences.

Dr. Sancha...I have always wondered about surfaces sticking together (or
"healing shut" as I used to say) after surgery (all kinds of surgery - not
just prostate - eg nasal passages etc). A 2-3 cm diameter hole is pretty
big hole (2.54 cm equal one inch) but when the urethra is in the relaxed
mode (ie you are not peeing), couldn't the tissue forming the channel
collapse on itself so to speak, or is what's left of the prostate too stiff
for that. And like you said if it did try to start sticking, would it get
loosened up when you urinate. In my TURP, the uro said he remove very
little (and my prostate was already small), so I would think there would be
a much greater chance for the surfaces to heal shut later on - does this
make sense.

I have had several nose surgeries in my life and when they remove turbinates
(for example), I guess it's the cotton they jam up your nose that prevents
the sticking together syndrome, but the cotton comes out in a couple or
three days, and I always wondered if the healing process (which has just
started) could still cause the closing off to take place. This applies to
so many other types of surgery also, and is interesting at best. I guess
that's why you surgeons make all the big bucks, until someone screams "it
didn't work" :-) :-) . Thanks again Dr. Sancha, and I apologize to everyone
for my rambling again. You know me :-) ...Pete



2. Prostatic ducts obstruction
Prostatic ducts can become obstructed, the glands keep secreting and
then you have a retention cyst. They are very common and easy to see
with ultrasound of the prostate. You can also see retention cysts
after TURP. So some of these ducts get obstructed with the surgery
as you sugggest, but this does not derive into major clinical
problems.
A TURP could cut the ejaculatory ducts if it is very aggressive and
penetrates the so called central zone of the prostate, but usually
TURP and PVP are restricted to the hyperplastic tissue, that derives
from the transitional zone of the prostate. So it is relatively rare
to obstruct the ejaculatory ducts with prostatic surgery. It is not a
cause of much concern for patients or urologists. Some young people
suffer obstruction of the ejaculatory ducts after infections, or for
unknown causes and they notice they ejaculate less volume of semen,
and they have fertility problems, but this obstruction rarely causes
pain or other symptoms.

3. prostatic urethra as a tube or duct:
I have not seen two prostatic urethras looking exactly the same. They
tend to be different, as prostatic shapes vary from person to person.
You never see two mouths that are exactly the same, do you? Some
prostatic urethras look from the inside like an open tube, other
prostatic urethras are not an open tube, but an obstructed tube,
because there are two masses of tissue that grow from the sides and
coapt in the midline. Some urethras look like a tube with a full
bladder (there is pressure inside the prostatic urethral lumen and it
opens up) and as a colapsed tube when the bladder is empty. In the
embryo, the urethra is a tube that is only lined with epithelial
cells. Then some buds start to develop from the urethra and these
buds invade the surrounding mesenchyma (this is the name of embryonal
tissue that has not yet differenciated into a mature tissue). These
buds are hollow bags of epithelial cells that will later
differenciate into the prostatic glands (the parenchyma - the
glandular tissue) - these cells will secrete the prostatic secretion,
and will produce the famous PSA. The surrounding tissue will
differenciate into the prostatic stroma (collagen, smooth muscle
fibers, elastin, and other components) - a scaffold that will support
the prostatic glands.

4. TURP and PVP and vaporization
TURP and PVP are performed with surgical instruments that allow for
continuous irrigation of the prostatic urethra and bladder. When
tissue is vaporized with a greenlight laser, or cut with a TURP
resectoscope, there are many tissue particles that float in this
irrigation fluid and are taken out of the patient through the scope.
They just do not condensate. TURP and PVP destroy the urethral lining
(the correct word should be endothelial - rather than epithelial,
endo means inside, and epi outside, so the epithelium applies to the
skin, and the endothelium to all "internal skins", it is used for any
lining of internal organs), but this epithelium grows again and when
you look inside after some time, you see it has regenerated
completely. In some areas there is some scar tissue, specially after
TURP, but as it happens with wounds in the skin, the regenerative
process manages to cover the wound surface completely.

5. Prostatic capsule.
The prostate does not have a proper capsule. It is surrounded by
fascial sheaths that are almost only visible under the microscope.

In a 20 year old prostate, there is an area near the bladder neck,
surrounding the urethral endothelium, the transitional zone, that will
be the origin of the benign hyperplastic tissue. It will start to grow
and it will progressively push the original prostatic tissue outwards.
In an old man with a big prostate, this growth of tissue from the area
surrounding the urethra will have pushed the original prostatic tissue
outwards, and between these two parts of the prostate, the central
hyperplastic tissue and the external original prostatic tissue there
is a very clear cleavage plane. When an open prostatectomy is
performed, the surgeon incises the prostate until he reaches this
cleavage plane, and then uses his finger to enucleate the
hyperplastic tissue, he breaks the urethra and extracts the BPH
tissue with a hole in the middle (like a donut) - the urethra. Then
the incission is closed with a suture. This gives the impression of a
"surgical capsule", that is tipically 5-10 mm thick, and this is
really the original prostate.
We surgeons talk about the capsule knowing that we refer to the
original prostatic tissue. When we perform TURP (well, I do not
perform TURP any longer) or PVP, we want to reach the "capsule" (the
surgical capsule), to make sure we remove all the hyperplastic tissue.
Apparently, some prostates are more distensible than others, and that
explains in part that some men with relatively small prostates are
very obstructed (the growth is not able to push the prostate
outwards, so it obstructs the urethral lumen) and some men with much
bigger prostates can urinate very well (a more distensible original
prostate allows this tissue to enlarge the prostate, and the urethra
is not so compressed). This also happens with e.g. kidney tumors. A
tumor inside the kidney can push the renal tissue and compress it and
when you look at the kidney it appears to be encapsulated, but what
you see is renal tissue that has been compressed and seems to form a
capsule around the tumor. Open prostatectomies on very big prostates
are like opening the skin of an orange (the surgical capsule or the
original prostatic tissue) and extracting the flesh (the hyperplastic
tissue)...

6.- liposuction of the prostate...

Prostatic tissue is quite elastic, but it is also quite rubery or
tough... there is no way of performing what you suggest...The
hiperplastic tissue is a benign tumor of the prostate, it has stroma
(collagen, muscle fibres, etc..) and parenchyma (glandular tissue).
Ellen Shapiro from new york has been studying the proportion of stroma
and parenchyma in BPH, a difficult question to investigate.... but
there are two components also in BPH. The smooth muscle in the stroma
responds with relaxation to alpha blockers. The glandular tissue
responds to finasteride with atrophy. Both mechanisms derive in
symptoms improvement in patients through different mechanisms.

It is a pity these google groups do not allow for drawing. It would be
very nice to use some drawings to explain these things.

My best wishes to all, I hope this was helpful.

Fernando Gómez Sancha
http://drgomezsancha2.blogspot.com


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