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<title>UTas ePrints - Embryonic Gonadal and Sexual Organ Development in a Small Viviparous Skink, Niveoscincus ocellatus</title>
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<meta content="Neaves, Linda" name="eprints.creators_name" />
<meta content="Wapstra, Erik" name="eprints.creators_name" />
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<meta content="The majority of research into the timing of gonad differentiation (and sex
determination) in reptiles has focused on oviparous species. This is largely because: (1) most reptiles
are oviparous; (2) it is easier to manipulate embryonic developmental conditions (e.g., temperature)
of eggs than oviductal embryos and (3) modes of sex determination in oviparous taxa were thought
to be more diverse since viviparity and environmental sex determination (ESD)/temperaturedependent
sex determination (TSD) were considered incompatible. However, recent evidence
suggests the two may well be compatible biological attributes, opening potential new lines of enquiry
into the evolution and maintenance of sex determination. Unfortunately, the baseline information
on embryonic development in viviparous species is lacking and information on gonad differentiation
and sexual organ development is almost non-existent. Here we present an embryonic morphological
development table (10 stages), the sequence of gonad differentiation and sexual organ development
for the viviparous spotted snow skink (Niveoscincus ocellatus). Gonad differentiation in this species
is similar to other reptilian species. Initially, the gonads are indifferent and both male and female
accessory ducts are present. During stage 2, in the middle third of development, differentiation
begins as the inner medulla regresses and the cortex thickens signaling ovary development, while the
opposite occurs in testis formation. At this point, the Mu¨llerian (female reproductive) duct regresses
in males until it is lost (stage 6), while females retain both ducts until after birth. In the later stages
of testis development, interstitial tissue forms in the medulla corresponding to maximum
development of the hemipenes in males and the corresponding regression in the females.
" name="eprints.abstract" />
<meta content="2006" name="eprints.date" />
<meta content="published" name="eprints.date_type" />
<meta content="Journal of Experimental Zoology" name="eprints.publication" />
<meta content="305A" name="eprints.volume" />
<meta content="74-82" name="eprints.pagerange" />
<meta content="10.1002/jez.a.249." name="eprints.id_number" />
<meta content="TRUE" name="eprints.refereed" />
<meta content="1548-8969" name="eprints.issn" />
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<meta content="Austin HB. 1988. Differentiation and development of the
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between testis and ovary determinations with possible
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Marmolejo-Valencia A. 1997. Correlation among themosensitive
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in the sea turtle Lepidochelys olivacea. Gen Comp Endocrinol
107:373–385.
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many means to an end. Reproduction 124:447–457.
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skink lizards (Niveoscincus microlepidotus). J Evol Biol 14:
120–128.
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Alligator mississippiensis, a species with temperaturedependent
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35:194–203.
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abdominal fat body mass in a small skink with an
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Wapstra E, Swain R, Jones SM, O’Reilly J. 1999. Geographic
and annual variation in reproductive cycles in the Tasmanian
spotted snow skink, Niveoscincus ocellatus (Squamata:
Scincidae). Aust J Zool 47:539–550.
Wapstra E, Swain R, O’Reilly JM. 2001. Geographic variation
in age and size at maturity in a small Australian viviparous
skink. Copeia 2001:646–655.
Wapstra E, Olsson M, Shine R, Edwards A, Swain R. 2003.
Selection of offspring sex by a viviparous lizard: evidence
for an adaptive explanation. Third International Symposium
on Vertebrate Sex Determination, Kona, Hawaii, March
24–28.
Wapstra E, Olsson M, Shine R, Edwards A, Swain R. 2004.
Maternal basking behaviour determines offspring sex in a
viviparous reptile. Proc R Soc, Lond B (Biol Lett) 271:
S230–S232.
Wibbels T, Bull JJ, Crews D. 1991. Chronology and morphology
of temperature-dependent sex determination. J Exp
Zool 260:371–381.
Wibbels T, Wilson C, Crews D. 1999. Mu¨llerian duct development
and regression in a turtle with temperature-dependent
sex determination. J Herpetol 33:149–152.
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<meta content="The majority of research into the timing of gonad differentiation (and sex
determination) in reptiles has focused on oviparous species. This is largely because: (1) most reptiles
are oviparous; (2) it is easier to manipulate embryonic developmental conditions (e.g., temperature)
of eggs than oviductal embryos and (3) modes of sex determination in oviparous taxa were thought
to be more diverse since viviparity and environmental sex determination (ESD)/temperaturedependent
sex determination (TSD) were considered incompatible. However, recent evidence
suggests the two may well be compatible biological attributes, opening potential new lines of enquiry
into the evolution and maintenance of sex determination. Unfortunately, the baseline information
on embryonic development in viviparous species is lacking and information on gonad differentiation
and sexual organ development is almost non-existent. Here we present an embryonic morphological
development table (10 stages), the sequence of gonad differentiation and sexual organ development
for the viviparous spotted snow skink (Niveoscincus ocellatus). Gonad differentiation in this species
is similar to other reptilian species. Initially, the gonads are indifferent and both male and female
accessory ducts are present. During stage 2, in the middle third of development, differentiation
begins as the inner medulla regresses and the cortex thickens signaling ovary development, while the
opposite occurs in testis formation. At this point, the Mu¨llerian (female reproductive) duct regresses
in males until it is lost (stage 6), while females retain both ducts until after birth. In the later stages
of testis development, interstitial tissue forms in the medulla corresponding to maximum
development of the hemipenes in males and the corresponding regression in the females.
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<h1 class="ep_tm_pagetitle">Embryonic Gonadal and Sexual Organ Development in a Small Viviparous Skink, Niveoscincus ocellatus</h1>
<p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Neaves, Linda</span> and <span class="person_name">Wapstra, Erik</span> and <span class="person_name">Birch, Debra</span> and <span class="person_name">Girling, Jane E.</span> and <span class="person_name">Joss, Jean M.P.</span> (2006) <xhtml:em>Embryonic Gonadal and Sexual Organ Development in a Small Viviparous Skink, Niveoscincus ocellatus.</xhtml:em> Journal of Experimental Zoology, 305A . pp. 74-82. ISSN 1548-8969</p><p style="margin-bottom: 1em" class="not_ep_block"></p><table style="margin-bottom: 1em" class="not_ep_block"><tr><td valign="top" style="text-align:center"><a href="http://eprints.utas.edu.au/2190/1/Embryonic_Gonadal.pdf"><img alt="[img]" src="http://eprints.utas.edu.au/style/images/fileicons/application_pdf.png" class="ep_doc_icon" border="0" /></a></td><td valign="top"><a href="http://eprints.utas.edu.au/2190/1/Embryonic_Gonadal.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />439Kb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input accept-charset="utf-8" value="2755" name="docid" type="hidden" /><div class=""><input value="Request a copy" name="_action_null" class="ep_form_action_button" onclick="return EPJS_button_pushed( '_action_null' )" type="submit" /> </div></form></td></tr></table><p style="margin-bottom: 1em" class="not_ep_block">Official URL: <a href="http://dx.doi.org/10.1002/jez.a.249">http://dx.doi.org/10.1002/jez.a.249</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">The majority of research into the timing of gonad differentiation (and sex
determination) in reptiles has focused on oviparous species. This is largely because: (1) most reptiles
are oviparous; (2) it is easier to manipulate embryonic developmental conditions (e.g., temperature)
of eggs than oviductal embryos and (3) modes of sex determination in oviparous taxa were thought
to be more diverse since viviparity and environmental sex determination (ESD)/temperaturedependent
sex determination (TSD) were considered incompatible. However, recent evidence
suggests the two may well be compatible biological attributes, opening potential new lines of enquiry
into the evolution and maintenance of sex determination. Unfortunately, the baseline information
on embryonic development in viviparous species is lacking and information on gonad differentiation
and sexual organ development is almost non-existent. Here we present an embryonic morphological
development table (10 stages), the sequence of gonad differentiation and sexual organ development
for the viviparous spotted snow skink (Niveoscincus ocellatus). Gonad differentiation in this species
is similar to other reptilian species. Initially, the gonads are indifferent and both male and female
accessory ducts are present. During stage 2, in the middle third of development, differentiation
begins as the inner medulla regresses and the cortex thickens signaling ovary development, while the
opposite occurs in testis formation. At this point, the Mu¨llerian (female reproductive) duct regresses
in males until it is lost (stage 6), while females retain both ducts until after birth. In the later stages
of testis development, interstitial tissue forms in the medulla corresponding to maximum
development of the hemipenes in males and the corresponding regression in the females.
</p></div><table style="margin-bottom: 1em" cellpadding="3" class="not_ep_block" border="0"><tr><th valign="top" class="ep_row">Item Type:</th><td valign="top" class="ep_row">Article</td></tr><tr><th valign="top" class="ep_row">Additional Information:</th><td valign="top" class="ep_row">see individual journal copyright transfer agreements</td></tr><tr><th valign="top" class="ep_row">Subjects:</th><td valign="top" class="ep_row"><a href="http://eprints.utas.edu.au/view/subjects/270604.html">270000 Biological Sciences > 270600 Physiology > 270604 Comparative Physiology</a></td></tr><tr><th valign="top" class="ep_row">ID Code:</th><td valign="top" class="ep_row">2190</td></tr><tr><th valign="top" class="ep_row">Deposited By:</th><td valign="top" class="ep_row"><span class="ep_name_citation"><span class="person_name">Dr Erik Wapstra</span></span></td></tr><tr><th valign="top" class="ep_row">Deposited On:</th><td valign="top" class="ep_row">15 Oct 2007 09:07</td></tr><tr><th valign="top" class="ep_row">Last Modified:</th><td valign="top" class="ep_row">09 Jan 2008 02:30</td></tr><tr><th valign="top" class="ep_row">ePrint Statistics:</th><td valign="top" class="ep_row"><a target="ePrintStats" href="/es/index.php?action=show_detail_eprint;id=2190;">View statistics for this ePrint</a></td></tr></table><p align="right">Repository Staff Only: <a href="http://eprints.utas.edu.au/cgi/users/home?screen=EPrint::View&eprintid=2190">item control page</a></p>
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