Herp Center Reptile Forums
TFH Publications
 
       
^^ The Advertisements above disappear once you log in. Not a member? Register Now, it's free! ^^
Results 1 to 9 of 9
  1. #1
    HH Block Leader kriminaal's Avatar
    Join Date
    Apr 2004
    Location
    Ontario, Canada
    Posts
    9,965

    New Sexing Technique

    Here is some info I recently became privy too. It's one of those "so simple things."


    ######################################## ############
    LEGAL NOTICE
    This info was copied from V a r a n u s . n l
    Varanus.nl is a monitor forum whose main focus is the breeding of monitors.
    The author is Dr. Danny Brown
    Enjoy.
    Again, it was NOT written by anyone here. It is posted on another website!

    ######################################## ############


    Hemipenal transillumination as a sexing technique in Varanids
    By Dr Danny Brown

    In 2007, Davis and Leavitt adapted a means of checking for gravidity in the very small skink species Xantusia vigilis as a means of sexing these very small skinks. I have adopted this technique (which I have called Hemipenal Transillumination technique or HTI technique) and have subsequently utilised it for sexing over 60 species of Australian lizards at various ages including dragons, geckos, monitors and skinks. The technique can be used on adults and juveniles and does not require that the individuals are sexually mature before the characteristics are visible. Like any technique, practise makes perfect and regular examination of individuals of known gender can allow you to develop a “feel” for what to expect and for which instrumentation works best for which species.
    The technique is as follows :
    The animal is positioned on its back so that the tail is directed towards the handler. A small, focussed, very bright (but non heat producing) light source is positioned behind the dorsal side of the tail to direct a beam of light through the tail base. I have found that visualisation is improved if the light beam is directed only behind the tail i.e. stray light around the edges of the tail are limited. This light allows the internal anatomy of the tail base to be visualised. In male lizards, the hemipenes are visualised both by their increased blood supply compared to adjacent tissue and the increased density of tissue in this area. They will be seen as either red dots, red ovals or as a “dull redness”. The latter refers to an overall red glow in the tail base. This is caused by a combination of an increase in blood supply and tissue density in the tail base (dorso-ventral thickening to accommodate the hemipenes) and degrees of “shadowing” (limiting light penetration) and “luminance” (as the light penetrates the hemipene and shines through what essentially becomes a red light filter) that creates an appearance of an overall red glow. In a female, an absence of red structures and a general yellowish glow is observed (as the light is only penetrating pure tail tissue). In some adults, the appearance will vary with mood, body temperature and breeding season depending on factors such as seasonal hemipenal size, voluntary extrusion of hemipenes , tail position and hemipenal blood supply changes (often one will appear more “engorged” than the other).
    The primary limitations of this technique are light intensity and tissue penetration of light. These two go hand in hand to some degree in that specimens with a dorso-ventral tail diameter of 8-10 mm or smaller are the most ideal candidates for this technique. Specific features such as heavy dorsal pigmentation, heavy dorsal scalation , tail thickness >8-10 mm and handling difficulties may also limit this technique although technique modifications (such as side on viewing) can be used to work around this. The “side on” technique involves (as the name suggests) placing the light source against the side of the tail. In those species where this technique is warranted due to dorsal visualisation issues, male exhibit the “dull redness” as described above whilst females exhibit a clean yellow glow. In species with lateral flattening of the tail and its base, such as water monitors, side on viewing through this significantly narrower area of tissue may allow hemipenes to be observed in the same detail as if the light is dorsally directed (as in other species).
    I maintain two torch types, an incandescent or halogen bulb producing a yellowish light and an LED torch producing bright white light. In some species, tail density is too thin for the use of an LED light as the light “blasts straight through” whereas an incandescent bulb produces a less harsh light that enhances the hemipenes more appropriately. In larger or spiny species, an incandescent bulb may be too subtle and a LED light is require to “blast past” the impediments to visualisation. The reduction of light scatter around the edges of the tail can also improve visualisation. This may be easily overcome using thick tape over the torch lens (with a viewing holes cut centrally) or by placing a cap over the torch end (plastic chair leg rubbers are ideal) with a viewing hole cut centrally. Oval shaped viewing holes are preferred over round ones. Technically, a purpose built sexing table or box could also be built and may allow a much larger torch to be used (or alternatively a dimmable electric globe). Be very careful with excessively intense light sources as these may also produce significant heat and may cause heat damage to the tail if the animal is left in position for an excessive period. The darker the room that the technique is used in, the better the visualisation. In the field, I have used this technique inside a dark backpack with good results.
    In summary, using this technique in monitors has produced the following results :
    • Very easy with small arboreal species (e.g. V. bushi, V. gilleni, V. caudolineatus).

    • Small terrestrial species (e.g. V. storri, V. brevicauda, V. primordius) are quite easy up to 10 mm tail thickness.

    • Juveniles of many smaller species sexable from 5 cm snout to vent length.

    • Juveniles of larger species may be sexed as long as tail thickness is > 10 mm. I have only had the opportunity to trial a single larger species being a 3 month old V. spenceri but in this specimen hemipenes were clearly visible (using a side on technique).

    • Some species may partly evert hemipenes when handled (e.g. V. primordius and V. brevicauda are notorious) making them difficult to visualise in this state (they are essentially tucked up under the cloacal rim but not visible externally) . This can be overcome by sexing whilst cooled or by placing light pressure at the hemipenal base with a finger to stop the hemipenes being extruded.

    • Hemipenes in adults will appear as long red ovals except if partly extruded (when they will be seen as red dots very close to the cloacal edge). In juveniles they may appear as thin ovals but are more commonly represented by red "dots".

    • Larger species can be sexed “side on” and males will appear as a “dull redness” rather than a yellow clear glow.

    Sexing of an adult male V. storri using HTI

    Sexing of an adult female V. storri using HTI

    Sexing of an juvenile male V. storri using HTI

    Sexing of an juvenile female V. storri using HTI



    I would welcome feedback from anybody with regards to the use of this technique in any other species(that I have not had access to for trials), particularly V. prasinus, glauerti, kingorum, pilbarensis and the larger monitor species.


    Sources :
    Davis, A.R. and Leavitt, D. H., 2007. “Candlelight vigilis: A noninvasive method for sexing small, sexually monomorphic lizards”, Herpetological Review. 38 (4): 402-404.

    Offline

    [/I]
    Mike

    Help us help others


    To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.






  2. #2
    Elite Member jfogle78's Avatar
    Join Date
    Nov 2008
    Posts
    191

    Re: New Sexing Technique

    That is very cool! Great find.

  3. #3
    Administrator Merlin's Avatar
    Join Date
    Mar 2004
    Location
    Oklahoma City, Ok.
    Posts
    31,757
    • My Reptiles

    Re: New Sexing Technique

    Now THATS cool! It will take a lot of the guesswork out of trying to sex immature lizards as well as those which lack a visual sexual dimorphism!
    Merlin,
    What's Life Without A Little Magic!

  4. #4
    Og_
    Og_ is offline
    Elite Member Og_'s Avatar
    Join Date
    Jul 2007
    Location
    Atlanta Georgia
    Posts
    2,302

    Re: New Sexing Technique

    I wish I knew of this 3 years ago! does anyone have a light that will shine through over 2 inches of flesh?

  5. #5
    Subscribed User teach920's Avatar
    Join Date
    Apr 2009
    Location
    Collierville, TN
    Posts
    1,835

    Re: New Sexing Technique

    I had no idea that there was so much "controversy" in regards to all this....What I did know, is that my own vet used this method when he was determining the sex of my Leopard Gecko (Roo).....before that visit, I just assumed Roo was too small/young to identify the gender, and basically figured the vet would only be able to do a fecal test.....but according to our vet "she" wasn't too young.......And both my kids and myself were utterly fascinated/amazed when our vet got his light out, and then told us about it, and demonstrated the above mentioned method to us.......It was one of the most informative/interesting vet visits I have ever been to..
    ~Connie~

    1.1.0 Bearded Dragons (Robby & Duchess)R.I.P. Citrus
    1.1.0 Leopard Geckos (Tigger & Roo)
    0.1.0 Uromastyx geryi (Roxie)
    2.3.8 Crested Geckos (Dragon, Eeyore, Kanga, Rabbit, & Winnie)
    0.1.0 albino pacman frog (Isabella)
    0.1.0 albino Whitewater Rosy Boa (Luna)
    1.1.0 Cats (Fluffy & Skinny)

    -- You can't scare me, I'm a Teacher of middle schoolers

  6. #6
    Technical Administrator Rich's Avatar
    Join Date
    Mar 2004
    Location
    Massachusetts
    Posts
    10,949
    Blog Entries
    16
    • My Reptiles

    Re: New Sexing Technique

    I have temporarily deleted every post within this thread that did not have to do with the actual thread itself. There was a vast amount of discussion pertaining to who discovered this first, the listed credits, and a desire to link to another website. None of this was relevant to the topic and the parties involved (myself included) were beating a dead horse.

    This issue is being discussed by the staff and the posts may return if that is the final decision.

    Thanks for understanding.

    To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

  7. #7
    Subscribed User Frognut's Avatar
    Join Date
    Aug 2008
    Location
    Charlotte, NC
    Posts
    3,324

    Re: New Sexing Technique

    We didn't need that other garbage -- it is a very interesting article, that was the important part!

    I tried it with my little Crested Geckos but they were a little too squirmy and I am still left with just a guess. But I didn't need a very big flashlight to see through their little tails. (I am hoping this technique is supposed to work on Crested Geckos...)

    Thanks for posting the article, and thanks Rich for getting rid of the other stuff.

    I'll wait until I have some extra hands to help. The Crested Geckos are so tiny still, and so squirmy -- I was afraid of taking the tail off during the process
    Frognut
    AKA Stephanie

    Check out my service dog blog:
    To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

    Where is the joy in life, without the little creatures that warm our hearts!

  8. #8
    Subscribed User teach920's Avatar
    Join Date
    Apr 2009
    Location
    Collierville, TN
    Posts
    1,835

    Re: New Sexing Technique

    Not sure if you're going to have any luck on your Crested Gecko...I was wondering the same thing about my 2 baby Crested Geckos last week and was told by someone very involved with Crested Geckos that this method wouldn't work with them....
    He stated only 2 ways possible for sexing Crested Geckos..one is by the appearance of tiny black pores in the males, (which can occur as early as 4-5 months) and the other way is wait and see if a bulge appears (which can take up to 10 months to appear.)
    I assumed he was correct, but in all honesty, am still wondering why this method wouldn't work with Crested Geckos...(maybe has something to do with the texture or skin??..I really have no idea....but would like to know if you find out otherwise.)
    ~Connie~

    1.1.0 Bearded Dragons (Robby & Duchess)R.I.P. Citrus
    1.1.0 Leopard Geckos (Tigger & Roo)
    0.1.0 Uromastyx geryi (Roxie)
    2.3.8 Crested Geckos (Dragon, Eeyore, Kanga, Rabbit, & Winnie)
    0.1.0 albino pacman frog (Isabella)
    0.1.0 albino Whitewater Rosy Boa (Luna)
    1.1.0 Cats (Fluffy & Skinny)

    -- You can't scare me, I'm a Teacher of middle schoolers

  9. #9
    Elite Member
    Join Date
    Jul 2009
    Location
    Sonoma, CA
    Posts
    511

    Re: New Sexing Technique

    A mini mag light works wonders because you can a just where the stream of light is concetrated. THis make Mindy a real girl (sounds like I'm talking about puppet or something x.x) not a Rex Mindy.

Similar Threads

  1. sexing
    By Trinket snake in forum Help *General*
    Replies: 7
    Last Post: 08-08-2006, 02:42 PM
  2. sexing igs
    By JamieP in forum Green Iguanas
    Replies: 4
    Last Post: 05-14-2006, 03:18 PM
  3. sexing igs
    By aiden_punx in forum Help *General*
    Replies: 1
    Last Post: 02-28-2006, 04:24 AM
  4. sexing them...
    By Jamie in forum Help *General*
    Replies: 3
    Last Post: 10-15-2005, 01:35 PM
  5. What's your feeding technique?
    By jacky in forum General Discussion
    Replies: 9
    Last Post: 07-18-2005, 11:39 PM

Tags for this Thread

Powered by Herp Center
Herp Center | Richard Brooks
© 2004 - 2014
All rights reserved.
Online Since 2004

All material appearing on this web site is copyright © Herp Center, except where stated, and cannot be reproduced without our express written permission.