Technical Stuff Every Prostate Milker Needs To Know – Structures Of The Anus And Rectum

Welcome to my resource page supporting my post on prostate milking. Here you will hopefully find out what every milker needs to know about the anal and rectal structures you will encounter whilst milking.

You won’t be able to see most of them, but you’ll certainly be able to feel them. :)
 

(your milk-ee will certainly feel them)     :)

 
In my ongoing efforts to achieve some sort of brevity, I cut out a humungous number of rants. Most of these were about having to do this huge set of posts, which in turn was because of what I felt were serious omissions in the currently available literature on the subject.

One of these rants was going to be on this page. But what with the brevity efforts and all, I cut it out.

But all is not lost!

I made a separate page of rants, all dedicated to the milking topic, and all cut out from the information pages.

Sort of like an out-takes page.     :)

Anyhow, you can go read them or not, at your leisure, and if you choose to.

So, now back to our regularly scheduled (rantless) programming.
 
 

The Histology Part

First: It is vitally important to maintain meticulous and thorough safety and hygiene related precautions throughout milking.

(yes, I did posts covering these which you can read, so you may stop panicking now)     ;)
 

Chart from the World Health Organisation on how to hygienically cleanse hands.
 
Copyright © World Health Organization 2008. All rights reserved. Used here by kind permission.
 
 
Ok, now on with the show. :)
 
 

Some Definitions, But This Section Is Mostly About Keratin

The anal and rectal walls are lined with mucous membranes. Mucous membranes also line the vagina, nose, mouth and lips.

Mucous membranes are covered and protected by an outer layer of epithelial cells.

Epithelial cells are to mucous membranes what the epidermis is to skin. The epidermis is actually made up of epithelial cells, but there are many more cells per square centimeter in the epithelium of the epidermis than there are covering the mucous membranes. Essentially, for our purposes, the point of all of this is relative delicacy, vulnerability to injury, and ability to protect what’s underneath.

And that’s where keratin makes a big kersploosh!

The epithelial layers of the vagina, nose, lips and anus are slightly keratinised. Keratin strengthens and toughens the surface of the epithelium. The more keratinised the cells, the tougher they will be. Ordinary skin has a lot more keratin in it than mucous membranes have. So ordinary skin is much stronger and more resilient than any mucous membrane.
 

(you may possibly have noticed this yourself already)     :)

 
Sometimes keratin is visible to the naked eye. If you’ve ever had or seen callouses on elbows, knees, or the sole of the foot, and noticed a kind of brownish darkening and hardening of the skin, keratin is what you’re observing.
 

The darker areas visible on the outer edges, heels, and balls of the feet have been darkened by keratin deposits. The paler areas, as are visible on the arches, are less keratinised.

Consistently stressing skin over time will result in keratin deposits forming to protect those areas. That is why foot arches are less keratinised, and those parts of the feet which touch the ground are more keratinised.
 
 
Vile Shoes
 
One of the reasons why a baby’s feet are so soft and pink is because the baby just hasn’t had the years of jumping on beds, running around barefoot, climbing on rocks, wearing vile shoes, or any of that other stuff that helps keratinise the soles of the feet.
 
The epithelial layer of the mucous membrane of the anus is thinner and less keratinised than that of the vagina, nose, or facial lips. As a result, it is much more vulnerable to stress and injury than the vagina, nose or lips.

The mucous membrane lining the rectum (where the prostate is accessed), is not keratinised at all, making it very vulnerable indeed.

I mean, it’s really difficult to get a rectum to jump on a bed or wear vile shoes to toughen that ole epitheluim up, y’know?     ;)
 
 

Epithelial Layers – Vagina And Oro-Labial

                        The vaginal wall                                 The facial lip           The oral mucosa

• Left: Cross section of the vaginal epithelium
• Right: Cross section of the facial lip and oral mucosa epithelia
   
  Images courtesy of, and Copyright © 2006 The University of Western Australia – School of Anatomy and Human Biology, and Dr Lutz Slomianka 1998-2006. Used with kind permission.

 
The keratinised epithelium of the vaginal wall is notably thinner than the keratinised epithelial layer of the facial lip.

For comparison, note the greatly reduced amount of keratin in the epithelial layer of the oral mucosa inside the mouth.
 
 

Epithelial Layers – The Recto-Anal Junction

Variously known as, the pectinate line, anocutaneous line, dentate line, anal verge, ano-rectal junction, recto-anal junction

• Ano-Rectal Junction: Cross section of the ano-rectal epithelium
   
  Images courtesy of The National Taiwan University College of Medicine. Copyright © 2004 The National Taiwan University College of Medicine. All Rights Reserved. Used with kind permission.

 
Note how very much thinner the epithelium of the anal and rectal walls are, as compared with the much thicker keratinised epithelial layers of the facial lip and the vaginal wall.
 
 
Important Differences
 
The relative difference in thickness and keratinisation between the epithelial layers of the vaginal wall, facial lip, and recto-anal junction are significant enough to be easily detectable on these slides.

If you look closely at the left portion of the recto-anal junction slide, it is possible to see the thin outer layer of slightly keratinised epithelial cells of the anus, the slightly thicker dark layer underneath, and the paler layer of the mucosa below.

For the purposes of being, um, like a sort of map thingy, please allow me to direct your attention towards the sphincter, which is out of frame to the left. The rectum begins at the junction as you see it from the centre of the image, and continues out of frame to the right. Note the decreasing thickness of the epithelial wall as it travels inwards towards the rectum.

Following the fashion trends this season of other transitions in the gastro-intestinal tract, the junction between the anus and the rectum is quite distinct. There is nothing at all gradual or subtle about the transformation from anus to rectum. The epithelial change from keratinised in the anus, to no keratin at all in the rectum, is sudden and very noticeable.
 

You can see for yourself, the recto-anal transition is about a subtle as an American ice hockey team during a championship match.
 
• Please especially note:     The prostate is accessed for milking through the rectal wall, which is incredibly thin and totally unkeratinised. The rectal epithelium is easily vulnerable to injury due to the absence of any strengthening keratin deposits. Please try to be un-ice-hockey-like when milking.
   
  This is important.

 
 

Other Stuff About The Rectum And Tissue Slides

The recto-anal junction is an important anatomical landmark. Although there are some similar structures to be found on either side of the line, several defining distinctions can differentiate them based on their relative location to this junction.

Haemorrhoids are a good example of this. In this image of the rectoanal junction from the NTU College of Medicine, a rectal haemorrhoid can be clearly seen. Rectal haemorrhoids are perfectly normal, and not painful, whereas anal haemorrhoids (as some of you will be unfortunate enough to know) are cringe-worthily horrible.

Yuk.     Ok, moving swiftly on…
 
 
Important Information

• In case you weren’t aware, the thin tissue shavings which are mounted on slides for us to view (as we see here), are stained using various methods and materials.
• I’m sure you really don’t care much about the details of how this is done.
• The tissue samples we see here are not the original colours they were when they were living in a human body.
• The tissue samples have been stained with dyes so that the structures will show up more clearly.
• Which they do.
• Just so you know. :)
• ps:   This is not at all like fake tan, k?     Just so we’re clear.     :)

 
So, the staining in the slide image of the anal wall reveals the structures which contribute to its function.
 
 

I’m Ready For My Close Up, Mr DeMille

      Close up of the recto-anal junction     Recto-anal junction with structure labels

• Right: Cross section of the recto-anal epithelium, at a higher magnification
• Left: Cross section of the recto-anal junction, with structure labels

 
In the left image of the recto-anal junction at increased magnification, the distinct change between the anus and the rectum is easy to see. Partway up the left side of the rectal haemorrhoid, there is an abrupt change from the keratinised smooth pink mucosa of the anus, to the non-keratinised epithelium of the rectum, with its distinctive crypts of Lieberkühn clearly visible in both images.
 
 

Getting To The Point Of All This (finally)

This point at which the anal canal ends and the rectum begins has various nomenclatures, including the pectinate line, anocutaneous line, dentate line, anal verge, anorectal junction, and rectoanal junction.

Whatever.

Essentially, as far as we milkers are concerned, the importance of the ano-rectal junction is the difference between keratin, and no keratin.
 

• Keratin means stronger and more resilient epithelial layers
• No keratin means very vulnerable to injury
   
  So the lesson for today, kids, is:
• It is extremely important to take great care and be very gentle whilst milking.
• This cannot be stressed enough – it is vitally important to maintain meticulous and thorough safety and hygiene precautions throughout milking. Please note the importance of taking extraordinarily good care not to distress or injure the epithelial cells of the anal or rectal wall whilst milking.

 
For more information on this please see the Medical Risks and Hygiene support pages for this Prostate Milking post.
 
 

Thank You

Out of all the articles I made in this series, this one was possibly the most difficult. A lot of this is so far outside my usual areas of expertise, I had a great deal of difficulty putting this page together in a way which was comprehensive, accurate, detailed-enough-but-no-more, and most of all, accessible to the lay reader.

I think I may possibly have succeeded, but I’m pretty sure I wouldn’t have been able to if it hadn’t been for the kind permissions of the individuals and institutions below who allowed me to make use of their work to illustrate mine.

I would now like to express my deeply felt appreciation to those individuals and institutions for their permission to use their work.
 
 
The People Who Made This Post Possible
 
The images of slides have been made available for use in my prostate milking resource by kind permission of the copyright holders. Below are details of the gracious people who granted that permission.
 
 

Labelled slides of the vagina, lip/oral mucosa and ano-rectal junction Copyright © 2006 by the School of Anatomy & Human Biology – University of Western Australia, and © Dr Lutz Slomianka 1998-2006. I sincerely thank Dr Slomianka for his kind permission to make use of these images here. I additionally thank Dr Slomianka for getting his histology pages hosted on the University College Cork servers, which just couldn’t be any handier for me! Thank you Dr Slomianka, you rock. :)

Unlabelled recto-anal junction images Copyright © 2004 by the National Taiwan University College of Medicine. I sincerely thank Dr Cheng-Kai Kao, the doctors and web administrators at NTU for their kind permission to make use of their images here. I’m very grateful. :)

I would also like to thank Ms Dolores Campanario at the World Health Organization for their kind permission to use their materials in these pages. All WHO materials Copyright © 2008 by the World Health Organization. All rights reserved.

I thank you for your kind generosity. :)
 
 

ps: Just In Case You’re Interested

In case you want more information about how far in the anus goes before it transitions into the rectum, here is an image from Gray’s Anatomy which may clarify stuff a bit in that department.

The anal canal does not become the rectum until after it goes beyond the anal sphincter muscle. At that point the rectum begins. In this anatomical drawing from Gray’s Anatomy, the transition from anus to rectum is clearly visible.
 

 
Ok, I’m really done here.     :)