As temperature-dependent sex determination (TSD) and homozygote or heterozygote genetic sex determination (GSD) exist in multiple reptilian taxa, they represent sex determination systems that have emerged de novo. Current investigations have revealed that the genetic mechanisms used by various reptilian species are similar to those used by other vertebrates. However, the recent completion or near completion of various reptilian genome projects suggests that new studies examining related species with and without TSD could begin to provide additional insight into the evolution of TSD and GSD in vertebrate ancestors. Major questions still remain concerning germ cell migration and specification, the differentiation of gonadal accessory cells, such as the Sertoli cells and granulosa cells of the developing testis and ovary, respectively, and the mechanisms by which gene expression is regulated during TSD events. Further, reptilian sentinels and their mechanisms of gonadogenesis will likely remain important indicator species for environmental health. Thus, ongoing and new investigations need to tie molecular information to gonadal morphogenesis and function in reptiles. Such data will not only provide important information for an understanding of the evolution of these phenomena in vertebrates, but could also provide an important understanding of the health of the environment around us.

Keywords:
CYP19 aromatase, DNA methylation, Endocrine-disrupting contaminants, Estrogen signal, Germ cell migration, Germ cell specification, Oogenesis, Spermatogenesis, Temperature-dependent sex determination
1.
Agrawal R, Wessely O, Anand A, Singh L, Aggarwal RK: Male-specific expression of Sox9 during gonad development of crocodile and mouse is mediated by alternative splicing of its proline-glutamine-alanine rich domain. FEBS J 276:4184-4196 (2009).
2.
Alföldi J, Di Palma F, Grabherr M, Williams C, Kong L, et al: The genome of the green anole lizard and a comparative analysis with birds and mammals. Nature 477:587-591 (2011).
3.
Anand A, Patel M, Lalremruata A, Singh AP, Agrawal R, et al: Multiple alternative splicing of Dmrt1 during gonadogenesis in Indian mugger, a species exhibiting temperature-dependent sex determination. Gene 425:56-63 (2008).
4.
Bachvarova RF, Crother BI, Johnson AD: Evolution of germ cell development in tetrapods: comparison of urodeles and amniotes. Evol Dev 11:603-609 (2009a).
5.
Bachvarova RF, Crother BI, Manova K, Chatfield J, Shoemaker CM, et al: Expression of Dazl and Vasa in turtle embryos and ovaries: evidence for inductive specification of germ cells. Evol Dev 11:525-534 (2009b).
6.
Badenhorst D, Stanyon R, Engstrom T, Valenzuela N: A ZZ/ZW microchromosome system in the spiny softshell turtle, Apalone spinifera, reveals an intriguing sex chromosome conservation in Trionychidae. Chromosome Res 21:137-147 (2013).
7.
Barske LA, Capel B: Estrogen represses SOX9 during sex determination in the red-eared slider turtle Trachemys scripta. Dev Biol 341:305-314 (2010).
8.
Baumann H, Casian JAR, Conover DO: Contrasting latitudinal variations in vertebral number and sex determination in Pacific versus Atlantic silverside fishes. Copeia 2012:341-350 (2012).
9.
Bell LR, Maine EM, Schedl P, Cline TW: Sex-lethal, a Drosophila sex determination switch gene, exhibits sex-specific RNA splicing and sequence similarity to RNA binding proteins. Cell 55:1037-1046 (1988).
10.
Bergeron JM, Crews D, McLachlan JA: PCBs as environmental estrogens: turtle sex determination as a biomarker of environmental contamination. Environ Health Perspect 102:780-781 (1994).
11.
Bergman A, Heindel J, Jobling S, Kidd K, Zoeller RT (eds): State of the science of endocrine disrupting chemicals 2012, in WHO/UNEP (Geneva 2012).
12.
Brown RD, Nicholson WE, Chick WT, Strott CA: Effect of o,p'-DDD on human adrenal steroid 11β-hydroxylation activity. J Clin Endocrinol Metab 36:730-733 (1973).
13.
Bull JJ: Sex determination in reptiles. Quart Rev Biol 55:3-21 (1980).
14.
Bull JJ, Bulmer MG: Longevity enhances selection of environmental sex determination. Heredity (Edinb) 63:315-320 (1989).
15.
Bull JJ, Gutzke WH, Crews D: Sex reversal by estradiol in three reptilian orders. Gen Comp Endocrinol 70:425-428 (1988).
16.
Burtis KC, Baker BS: Drosophila doublesex gene controls somatic sexual differentiation by producing alternatively spliced mRNAs encoding related sex-specific polypeptides. Cell 56:997-1010 (1989).
17.
Calderón ML, De Pérez GR, Ramíres Pinilla MPR: Morphology of the ovary of Caiman crocodilus (Crocodylia: Alligatoridae). Ann Anat 186:13-24 (2004).
18.
Callebaut M: [3H]Uridine incorporation during previtellogenesis and early vitellogenesis in oocytes of chick (Gallus gallus). J Embryol Exp Morphol 20:169-174 (1968a).
19.
Callebaut M: Extracorporal development of quail oocytes. Experientia 24:1242-1243 (1968b).
20.
Callebaut M, Van Nassauw L, Harrisson F: Comparison between oogenesis and related ovarian structures in a reptile, Pseudemys scripta elegans (turtle) and in a bird Coturnix coturnix japonica (quail). Reprod Nutr Dev 37:233-252 (1997).
21.
Cardone A: Testicular toxicity of methyl thiophanate in the Italian wall lizard (Podarcis sicula): morphological and molecular evaluation. Ecotoxicology 21:512-523 (2012).
22.
Chapus C, Edwards SV: Genome evolution in Reptilia: in silico chicken mapping of 12,000 BAC-end sequences from two reptiles and a basal bird. BMC Genomics 10(suppl 2):S8 (2009).
23.
Charnov EL, Bull J: When is sex environmentally determined? Nature 266:828-830 (1977).
24.
Colborn T, vom Saal FS, Soto AM: Developmental effects of endocrine-disrupting chemicals in wildlife and humans. Environ Health Perspect 101:378-384 (1993).
25.
Cole CJ: Karyotypes of the five monotypic species groups of lizards in the genus Sceloporus. Am Mus Novit 2450:1-17 (1971).
26.
Conover DO: Adaptive significance of temperature-dependent sex determination in a fish. Am Nat 123:297-313 (1984).
27.
Contractor RG, Foran CM, Li S, Willett KL: Evidence of gender- and tissue-specific promoter methylation and the potential for ethinylestradiol-induced changes in Japanese medaka (Oryzias latipes) estrogen receptor and aromatase genes. J Toxicol Environ Health A 67:1-22 (2004).
28.
Crain DA, Guillette LJ Jr, Rooney AA, Pickford DB: Alterations in steroidogenesis in alligators (Alligator mississippiensis) exposed naturally and experimentally to environmental contaminants. Environ Health Perspect 105:528-533 (1997).
29.
Crews D, Wibbels T, Gutzke WHN: Action of sex steroid hormones on temperature-induced sex determination in the snapping turtle (Chelydra serpentina). Gen Comp Endocrinol 76:159-166 (1989).
30.
Deeming DC: Prevalence of TSD in crocodilians, in Valenzuela N. Lance VA (eds): Temperature-Dependent Sex Determination in Vertebrates (Smithsonian Books, Washington DC 2004).
31.
Deeming DC, Ferguson MWJ: Effects of incubation temperature on the growth and development of embryos of Alligator mississippiensis. J Comp Physiol B 159:183-193 (1989).
32.
DeFalco T, Capel B: Gonad morphogenesis in vertebrates: divergent means to a convergent end. Annu Rev Cell Dev Biol 25:457-482 (2009).
33.
De Santa Barbara P, Bonneaud N, Boizet B, Desclozeaux M, Moniot B, et al: Direct interaction of SRY-related protein SOX9 and steroidogenic factor 1 regulates transcription of the human anti-Müllerian hormone gene. Mol Cell Biol 18:6653-6665 (1998).
34.
DiNapoli L, Capel B: Germ cell depletion does not alter the morphogenesis of the fetal testis or ovary in the red-eared slider turtle (Trachemys scripta). J Exp Zool B Mol Dev Evol 308:236-241 (2007).
35.
Dorizzi M, Richard-Mercier N, Desvages G, Girondot M, Pieau C: Masculization of gonads by aromatase inhibitors in a turtle with temperature-dependent sex determination. Differentiation 58:1-8 (1994).
36.
Dournon C, Houillon C, Pieau C: Temperature sex-reversal in amphibians and reptiles. Int J Dev Biol 34:81-92 (1990).
37.
Evans CT, Ledesma DB, Schulz TZ, Simpson ER, Mendelson CR: Isolation and characterization of a complementary DNA specific for human aromatase-system cytochrome P-450 mRNA. Proc Natl Acad Sci USA 83:6387-6391 (1986).
38.
Ewert MA, Jackson DR, Nelson CE: Patterns of temperature-dependent sex determination in turtles. J Exp Zool 270:3-15 (1994).
39.
Extavour CG, Akam M: Mechanisms of germ cell specification across the metazoans: epigenesis and preformation. Development 130:5869-5884 (2003).
40.
Eyal-Giladi H, Ginsburg M, Farbarov A: Avian primordial germ cells are of epiblastic origin. J Embryol Exp Morphol 65:139-147 (1981).
41.
Ezaz T, Stiglec R, Veyrunes F, Marshall Graves JA: Relationships between vertebrate ZW and XY sex chromosome systems. Curr Biol 16:R736-R743 (2006).
42.
Ferguson MWJ: Reproductive biology and embryology of the crocodilians, in Gans C, Billett FS, Maderson PFA (eds): Biology of the Reptilia: Development, vol 14, pp 329-491 (J. Wiley and Sons, New York 1985).
43.
Fiala JC: Reconstruct: a free editor for serial section microscopy. J Microsc 218:52-61 (2005).
44.
Forbes TR: The development of the reproductive system of a lizard, Anolis carolinensis. Am J Anat 98:139-157 (1956).
45.
Foster JW, Dominguez-Steglich MA, Guioli S, Kwok C, Weller PA, et al: Campomelic dysplasia and autosomal sex reversal caused by mutations in an SRY-related gene. Nature 372:525-530 (1994).
46.
Fujimoto T, Ukeshima A, Miyayama Y, Horio F, Ninomiya E: Observations of primordial germ cells in the turtle embryo (Caretta caretta): light and electron microscopic studies. Dev Growth Differ 21:3-10 (1979).
47.
Gabriel WN, Blumberg B, Sutton S, Place AR, Lance VA: Alligator aromatase cDNA sequence and its expression in embryos at male and female incubation temperatures. J Exp Zool 290:439-448 (2001).
48.
Garrison AW, Guillette LJ Jr, Wiese TE, Avants JK: Persistent organochlorine pesticides and their metabolites in alligator livers from Lakes Apopka and Woodruff, Florida, USA. Int J Environ Anal Chem 90:159-170 (2010).
49.
Gautam M, Mathur A, Khan MA, Majumdar SS, Rai U: Transcriptome analysis of spermatogenically regressed, recrudescent and active phase testis of seasonally breeding wall lizards Hemidactylus flaviviridis. PLoS One 8:e58276 (2013).
50.
Gilbert SF: Developmental Biology, ed 9 (Sinauer Associates, Sunderland 2010).
51.
Ginsburg M, Eyal-Giladi H: Primordial germ cells of the young chick blastoderm originate from the central zone of the area pellucida irrespective of the embryo-forming process. Development 101:209-219 (1987).
52.
Giroux DJ: Lake Apopka Revisited: A Correlational Analysis of Nesting Anomalies and DDT Contaminants, thesis (University of Florida, Gainesville 1998).
53.
Godfrey MH, Delmas V, Girondot M: Assessment of patterns of temperature-dependent sex determination using maximum likelihood model selection. Ecoscience 10:265-272 (2003).
54.
Gómez D, Ramírez-Pinilla MP: Ovarian histology of the placentotrophic Mabuya mabouya (Squamata, Scincidae). J Morphol 259:90-105 (2004).
55.
Gray LE Jr, Monosson E, Kelce WR: Emerging issues: the effects of endocrine disrupters on reproductive development, in DiGiulio RT, Monosson E (eds): Interconnections between Human and Ecosystem Health, pp 45-82 (Chapman and Hall, London 1996).
56.
Gribbins KM: Reptilian spermatogenesis: a histological and ultrastructural perspective. Spermatogenesis 1:250-269 (2011).
57.
Gribbins KM, Elsey RM, Gist DH: Cytological evaluation of the germ cell development strategy within the testis of the American alligator, Alligator mississippiensis. Acta Zool 87:59-69 (2006).
58.
Guillette LJ Jr: Endocrine disrupting contaminants - beyond the dogma. Environ Health Perspect 114(suppl 1):9-12 (2006).
59.
Guillette LJ Jr, Iguchi T: Contaminant-induced endocrine and reproductive alterations in reptiles. Pure Appl Chem 75:2275-2286 (2003).
60.
Guillette LJ Jr, Iguchi T: Ecology. Life in a contaminated world. Science 337:1614-1615 (2012).
61.
Guillette LJ Jr, Moore BC: Environmental contaminants, fertility, and multioocytic follicles: a lesson from wildlife? Semin Reprod Med 24:134-141 (2006).
62.
Guillette LJ Jr, Gross TS, Masson GR, Matter JM, Percival HF, Woodward AR: Developmental abnormalities of the gonad and abnormal sex hormone concentrations in juvenile alligators from contaminated and control lakes in Florida. Environ Health Perspect 102:680-688 (1994).
63.
Guillette LJ Jr, Brock JW, Rooney AA, Woodward AR: Serum concentrations of various environmental contaminants and their relationship to sex steroid concentrations and phallus size in juvenile American alligators. Arch Environ Contam Toxicol 36:447-455 (1999).
64.
Guillette LJ Jr, Crain DA, Gunderson MP, Kools SAE, Milnes MR, et al: Alligators and endocrine disrupting contaminants: a current perspective. Am Zool 40:438-452 (2000).
65.
Guillette LJ Jr, Vonier PM, McLachlan JA: Affinity of the alligator estrogen receptor for serum pesticide contaminants. Toxicology 181-182:151-154 (2002)
66.
Guillette LJ Jr, Kools S, Gunderson MP, Bermudez DS: DDT and its analogues: new insights into their endocrine disruptive effects on wildlife, in Norris DO, Carr JA (eds): Endocrine Disruption: Biological Basis for Health Effects in Wildlife and Humans, pp 332-355 (Oxford University Press, New York 2006).
67.
Guraya SS, Varma SK: Morphology of ovarian changes during reproductive-cycle of house lizard, Hemidactylus flaviviridis. Acta Morphol Neerl Scand 14:165-191 (1976).
68.
Hamlin HJ, Guillette LJ Jr: Embryos as targets of endocrine disrupting contaminants in wildlife. Birth Defects Res C Embryo Today 93:19-33 (2011).
69.
Heinz GH, Percival HF, Jennings ML: Contaminants in American alligator eggs from Lake Apopka, Lake Griffin and Lake Okeechobee, Florida. Environ Monit Assess 16:277-285 (1991).
70.
Hernández-Franyutti A, Uribe Aranzábal MC, Guillette LJ Jr: Oogenesis in the viviparous matrotrophic lizard Mabuya brachypoda. J Morphol 265:152-164 (2005).
71.
Hubert J: Origin and development of oocytes, in Gans C (ed): Biology of the Reptilia, vol 14, pp 43-50 (Wiley, New York 1969).
72.
Iguchi T, Takasugi N, Bern HA, Mills KT: Frequent occurrence of polyovular follicles in ovaries of mice exposed neonatally to diethylstilbestrol. Teratology 34:29-35 (1986).
73.
Iguchi T, Watanabe H, Katsu Y: Developmental effects of estrogenic agents on mice, fish, and frogs: a mini-review. Horm Behav 40:248-251 (2001).
74.
Janzen FJ, Paukstis GL: A preliminary test of the adaptive significance of environmental sex determination in reptiles. Evolution 45:435-440 (1991).
75.
Janzen FJ, Krenz JG: Phylogenetics: which was first, TSD or GSD, in Valenzuela N, Lance VA (eds): Temperature-Dependent Sex Determination in Vertebrates, (Smithsonian Books, Washington DC 2004).
76.
Jeyasuria P, Roosenburg WM, Place AR: Role of P-450 aromatase in sex determination of the diamondback terrapin, Malaclemys terrapin. J Exp Zool 270:95-111 (1994).
77.
Jones RE, Swain T, Guillette LJ Jr, Fitzgerald KT: The comparative anatomy of lizard ovaries, with emphasis on the number of germinal beds. J Herpetol 16:240-252 (1982).
78.
Katsu Y, Bermudez DS, Braun EL, Helbing C, Miyagawa S, Gunderson MP, et al: Molecular cloning of the estrogen and progesterone receptors of the American alligator. Gen Comp Endocrinol 136:122-133 (2004).
79.
Katsu Y, Ichikawa R, Ikeuchi T, Kohno S, Guillette LJ Jr, Iguchi T: Molecular cloning and characterization of estrogen, androgen, and progesterone nuclear receptors from a freshwater turtle (Pseudemys nelsoni). Endocrinology 149:161-173 (2008).
80.
Katsu Y, Matsubara K, Kohno S, Matsuda Y, Toriba M, et al: Molecular cloning, characterization, and chromosome mapping of reptilian estrogen receptors. Endocrinology 151:5710-5720 (2010).
81.
Kelce WR, Stone CR, Laws SC, Gray LE, Kemppainen JA, Wilson EM: Persistent DDT metabolite p,p′-DDE is a potent androgen receptor antagonist. Nature 375:581-585 (1995).
82.
Kobayashi Y, Sunobe T, Kobayashi T, Nagahama Y, Nakamura M: Promoter analysis of two aromatase genes in the serial-sex changing gobiid fish, Trimma okinawae. Fish Physiol Biochem 31:123-127 (2005).
83.
Kohno S, Guillette LJ Jr: Endocrine disruption and reptiles: Using the unique attributes of temperature-dependent sex determination to assess impacts, in Matthiessen P (ed): Endocrine Disrupters: Hazard Testing and Assessment Methods (John Wiley & Sons, Hoboken 2013).
84.
Kohno S, Katsu Y, Urushitani H, Ohta Y, Iguchi T, Guillette LJ Jr: Potential contributions of heat shock proteins to temperature-dependent sex determination in the American alligator. Sex Dev 4:73-87 (2010).
85.
Lance VA, Bogart MH: Disruption of ovarian development in alligator embryos treated with an aromatase inhibitor. Gen Comp Endocrinol 86:59-71 (1992).
86.
Lang JW, Andrews HV: Temperature-dependent sex determination in crocodilians. J Exp Zool 270:28-44 (1994).
87.
Licht P, Denver RJ, Pavgi S: Temperature dependence of in vitro pituitary, testis, and thyroid secretion in a turtle, Pseudemys scripta. Gen Comp Endocrinol 76:274-285 (1989).
88.
Masson GR, Guillette LJ Jr: FSH-induced gonadal development in juvenile lizards, Eumeces obsoletus. J Exp Zool A Comp Exp Biol 236:343-351 (1985).
89.
Matsumoto Y, Crews D: Molecular mechanisms of temperature-dependent sex determination in the context of ecological developmental biology. Mol Cell Endocrinol 354:103-110 (2012).
90.
Matsumoto Y, Buemio A, Chu R, Vafaee M, Crews D: Epigenetic control of gonadal aromatase (cyp19a1) in temperature-dependent sex determination of red-eared slider turtles. PLoS One 8:e63599 (2013).
91.
Matter JM, McMurry CS, Anthony AB, Dickerson RL: Development and implementation of endocrine biomarkers of exposure and effects in American alligators (Alligator mississippiensis). Chemosphere 37:1905-1914 (1998).
92.
McPhaul MJ, Noble JF, Simpson ER, Mendelson CR, Wilson JD: The expression of a functional cDNA encoding the chicken cytochrome P-450arom (aromatase) that catalyzes the formation of estrogen from androgen. J Biol Chem 263:16358-16363 (1988).
93.
Milnes MR, Guillette LJ Jr: Alligator tales: new lessons about environmental contaminants from a sentinel species. Bioscience 58:1027-1036 (2008).
94.
Milnes MR, Roberts R, Guillette LJ Jr: Effects of incubation temperature and estrogen exposure on aromatase activity in the brain and gonads of embryonic alligators. Environ Health Perspect 110(suppl 3):393-396 (2002).
95.
Milnes MR, Bryan TA, Medina JG, Gunderson MP, Guillette LJ Jr: Developmental alterations as a result of in ovo exposure to the pesticide metabolite p,p′-DDE in Alligator mississippiensis. Gen Comp Endocrinol 144:257-263 (2005).
96.
Milnes MR, Bryan TA, Katsu Y, Kohno S, Moore BC, et al: Increased posthatching mortality and loss of sexually dimorphic gene expression in alligators (Alligator mississippiensis) from a contaminated environment. Biol Reprod 78:932-938 (2008).
97.
Moodley GK, van Wyk JH: Folliculogenesis and ovarian histology of the oviparous gecko, Hemidactylus mabouia (Sauria: Gekkonidae). Afr J Herpetol 56:115-135 (2007).
98.
Moore BC, Uribe-Aranzabal MC, Boggs AS, Guillette LJ Jr: Developmental morphology of the neonatal alligator (Alligator mississippiensis) ovary. J Morphol 269:302-312 (2008).
99.
Moore BC, Hamlin HJ, Botteri NL, Guillette LJ Jr: Gonadal mRNA expression levels of TGFβ superfamily signaling factors correspond with post-hatching morphological development in American alligators. Sex Dev 4:62-72 (2010a).
100.
Moore BC, Hamlin HJ, Botteri NL, Lawler AN, Mathavan KK, Guillette LJ Jr: Posthatching development of Alligator mississippiensis ovary and testis. J Morphol 271:580-595 (2010b).
101.
Moore BC, Kohno S, Cook RW, Alvers AL, Hamlin HJ, et al: Altered sex hormone concentrations and gonadal mRNA expression levels of activin signaling factors in hatchling alligators from a contaminated Florida lake. J Exp Zool A Ecol Genet Physiol 313:218-230 (2010c).
102.
Moore BC, Milnes MR, Kohno S, Katsu Y, Iguchi T, Guillette LJ Jr: Influences of sex, incubation temperature, and environmental quality on gonadal estrogen and androgen receptor messenger RNA expression in juvenile American alligators (Alligator mississippiensis). Biol Reprod 82:194-201 (2010d).
103.
Moore BC, Roark AM, Kohno S, Hamlin HJ, Guillette LJ Jr: Gene-environment interactions: the potential role of contaminants in somatic growth and the development of the reproductive system of the American alligator. Mol Cell Endocrinol 354:111-120 (2012).
104.
Morais da Silva S, Hacker A, Harley V, Goodfellow P, Swain A, Lovell-Badge R: Sox9 expression during gonadal development implies a conserved role for the gene in testis differentiation in mammals and birds. Nat Genet 14:62-68 (1996).
105.
Moreno-Mendoza N, Harley VR, Merchant-Larios H: Differential expression of SOX9 in gonads of the sea turtle Lepidochelys olivacea at male- or female-promoting temperatures. J Exp Zool 284:705-710 (1999).
106.
Moreno-Mendoza N, Harley VR, Merchant-Larios H: Temperature regulates SOX9 expression in cultured gonads of Lepidochelys olivacea, a species with temperature sex determination. Dev Biol 229:319-326 (2001).
107.
Morrish BC, Sinclair AH: Vertebrate sex determination: many means to an end. Reproduction 124:447-457 (2002).
108.
Motta CM, Scanderbeg MC, Filosa S, Andreuccetti P: Role of pyriform cells during the growth of oocytes in the lizard Podarcis sicula. J Exp Zool 273:247-256 (1995).
109.
Murdock C, Wibbels T: Cloning and expression of aromatase in a turtle with temperature-dependent sex determination. Gen Comp Endocrinol 130:109-119 (2003).
110.
Navarro-Martín L, Viñas J, Ribas L, Díaz N, Gutiérrez A, et al: DNA methylation of the gonadal aromatase (cyp19a) promoter is involved in temperature-dependent sex ratio shifts in the European sea bass. PLoS Genet 7:e1002447 (2011).
111.
Oreal E, Pieau C, Mattei MG, Josso N, Picard JY, et al: Early expression of AMH in chicken embryonic gonads precedes testicular SOX9 expression. Dev Dyn 212:522-532 (1998).
112.
Organ CL, Janes DE, Meade A, Pagel M: Genotypic sex determination enabled adaptive radiations of extinct marine reptiles. Nature 461:389-392 (2009).
113.
Ospina-Alvarez N, Piferrer F: Temperature-dependent sex determination in fish revisited: prevalence, a single sex ratio response pattern, and possible effects of climate change. PLoS One 3:e2837 (2008).
114.
Packard GC, Packard MJ, Miller K, Boardman TJ: Influence of moisture, temperature and substrate on snapping turtle eggs and embryos. Ecology 68:983-993 (1987).
115.
Parrott BB, Kohno S, Cloy-McCoy JA, Guillette LJ Jr: Differential incubation temperatures result in dimorphic DNA methylation patterning of the SOX9 and aromatase promoters in gonads of alligator (Alligator mississippiensis) embryos. Biol Reprod 90:2 (2014).
116.
Pérez-Bermúdez E, Ruiz-Urquiola A, Lee-González I, Petric B, Almaguer-Cuenca N, et al: Ovarian follicular development in the hawksbill turtle (Cheloniidae: Eretmochelys imbricata L.). J Morphol 273:1338-1352 (2012).
117.
Pieau C, Dorizzi M: Oestrogens and temperature-dependent sex determination in reptiles: all is in the gonads. J Endocrinol 181:367-377 (2004).
118.
Pieau C, Dorizzi M, Richard-Mercier N, Desvages G: Sexual differentiation of gonads as a function of temperature in the turtle Emys orbicularis: endocrine function, intersexuality and growth. J Exp Zool 281:400-408 (1998).
119.
Pokorna M, Kratochvil L: Phylogeny of sex-determining mechanisms in squamate reptiles: are sex chromosomes an evolutionary trap? Zool J Linn Soc-Lond 156:168-183 (2009).
120.
Radder R, Shine R: Germinal bed condition in a polyautochronic single-clutched lizard, Bassiana duperreyi (Scincidae). Amphib-reptil 28:159-162 (2007).
121.
Radder RS, Pizzatto L, Shine R: Morphological correlates of life-history variation: is lizard clutch size related to the number of germinal beds in the ovary? Biol J Linn Soc Lond 94:81-88 (2008).
122.
Raymond CS, Shamu CE, Shen MM, Seifert KJ, Hirsch B, et al: Evidence for evolutionary conservation of sex-determinng genes. Nature 391:691-695 (1998).
123.
Rhen T, Lang JW: Temperature-dependent sex determination in the snapping turtle: manipulation of the embryonic sex steroid environment. Gen Comp Endocrinol 96:243-254 (1994).
124.
Richard-Mercier N, Dorizzi M, Desvages G, Girondot M, Pieau C: Endocrine sex reversal of gonads by the aromatase inhibitor Letrozole (CGS 20267) in Emys orbicularis, a turtle with temperature-dependent sex determination. Gen Comp Endocrinol 100:314-326 (1995).
125.
Rooney AA: Variation in the endocrine and immune system of juvenile alligators: environmental influence on physiology. Thesis, Gainesville, University of Florida (1998).
126.
Russell LD: Histological and Histopathological Evaluation of the Testis, ed 1 (Cache River Press, Clearwater 1990).
127.
Shaffer HB, Minx P, Warren DE, Shedlock AM, Thomson RC, et al: The western painted turtle genome, a model for the evolution of extreme physiological adaptations in a slowly evolving lineage. Genome Biol 14:R28 (2013).
128.
Shen W, Park BW, Toms D, Li J: Midkine promotes proliferation of primordial germ cells by inhibiting the expression of the deleted in azoospermia-like gene. Endocrinology 153:3482-3492 (2012).
129.
Shoemaker C, Ramsey M, Queen J, Crews D: Expression of Sox9, Mis, and Dmrt1 in the gonad of a species with temperature-dependent sex determination. Dev Dyn 236:1055-1063 (2007).
130.
Shoemaker CM, Crews D: Analyzing the coordinated gene network underlying temperature-dependent sex determination in reptiles. Semin Cell Dev Biol 20:293-303 (2009).
131.
Shoemaker-Daly CM, Jackson K, Yatsu R, Matsumoto Y, Crews D: Genetic network underlying temperature-dependent sex determination is endogenously regulated by temperature in isolated cultured Trachemys scripta gonads. Dev Dyn 239:1061-1075 (2010).
132.
Sifuentes-Romero I, Merchant-Larios H, Milton SL, Moreno-Mendoza N, Díaz-Hernández V, García-Gasca A: RNAi-mediated gene silencing in a gonad organ culture to study sex determination mechanisms in sea turtle. Genes 4:293-305 (2013).
133.
Smith CA, Joss JMP: Steroidogenic enzyme activity and ovarian differentiation in the saltwater crocodile, Crocodylus porosus. Gen Comp Endocrinol 93:232-245 (1994).
134.
Smith CA, Elf PK, Lang JW, Joss JMP: Aromatase enzyme-activity during gonadal sex-differentiation in alligator embryos. Differentiation 58:281-290 (1995).
135.
Smith CA, McClive PJ, Western PS, Reed KJ, Sinclair AH: Conservation of a sex-determining gene. Nature 402:601-602 (1999).
136.
Smith CA, Roeszler KN, Ohnesorg T, Cummins DM, Farlie PG, et al: The avian Z-linked gene DMRT1 is required for male sex determination in the chicken. Nature 461:267-271 (2009).
137.
Spotila LD, Spotila JR, Hall SE: Sequence and expression analysis of WT1 and Sox9 in the red-eared slider turtle, Trachemys scripta. J Exp Zool 281:417-427 (1998).
138.
St John JA, Braun EL, Isberg SR, Miles LG, Chong AY, et al: Sequencing three crocodilian genomes to illuminate the evolution of archosaurs and amniotes. Genome Biol 13:415 (2012).
139.
Tanaka M, Telecky TM, Fukada S, Adachi S, Chen S, Nagahama Y: Cloning and sequence analysis of the cDNA encoding P-450 aromatase (P450arom) from a rainbow trout (Oncorhynchus mykiss) ovary; relationship between the amount of P450arom mRNA and the production of oestradiol-17β in the ovary. J Mol Endocrinol 8:53-61 (1992).
140.
Teranishi M, Shimada Y, Hori T, Nakabayashi O, Kikuchi T, et al: Transcripts of the MHM region on the chicken Z chromosome accumulate as non-coding RNA in the nucleus of female cells adjacent to the DMRT1 locus. Chromosome Res 9:147-165 (2001).
141.
Tokunaga S: Temperature-dependent sex determination in Gekko japonicus (Gokkonidae, Reptilia). Dev Growth Differ 27:117-120 (1985).
142.
Torres Maldonado LC, Landa Piedra A, Moreno Mendoza N, Marmolejo Valencia A, Meza Martínez A, Merchant Larios H: Expression profiles of Dax1, Dmrt1, and Sox9 during temperature sex determination in gonads of the sea turtle Lepidochelys olivacea. Gen Comp Endocrinol 129:20-26 (2002).
143.
Tran D, Muesy-Dessole N, Josso N: Anti-Müllerian hormone is a functional marker of foetal Sertoli cells. Nature 269:411-412 (1977).
144.
Tsunekawa N, Naito M, Sakai Y, Nishida T, Noce T: Isolation of chicken vasa homolog gene and tracing the origin of primordial germ cells. Development 127:2741-2750 (2000).
145.
Tyler CR, Jobling S, Sumpter JP: Endocrine disruption in wildlife: a critical review of the evidence. Crit Rev Toxicol 28:319-361 (1998).
146.
Uchida D, Yamashita M, Kitano T, Iguchi T: Oocyte apoptosis during the transition from ovary-like tissue to testes during sex differentiation of juvenile zebrafish. J Exp Biol 205:711-718 (2002).
147.
Uribe MCA, Guillette LJ Jr: Oogenesis and ovarian histology of the American alligator Alligator mississippiensis. J Morphol 245:225-240 (2000).
148.
Uribe MDCA, Portales GL, Guillette LJ Jr: Ovarian folliculogenesis in the oviparous Mexican lizard Ctenosaura pectinata. J Morphol 230:99-112 (1996).
149.
Urushitani H, Katsu Y, Miyagawa S, Kohno S, Ohta Y, et al: Molecular cloning of anti-Müllerian hormone from the American alligator, Alligator mississippiensis. Mol Cell Endocrinol 333:190-199 (2011).
150.
Valleley EM, Harrison CJ, Cook Y, Ferguson MW, Sharpe PT: The karyotype of Alligator mississippiensis, and chromosomal mapping of the ZFY/X homologue, Zfc. Chromosoma 103:502-507 (1994).
151.
Valleley EMA, Cartwright EJ, Croft NJ, Markham AF, Coletta PL: Characterisation and expression of Sox9 in the leopard gecko, Eublepharis macularius. J Exp Zool 291:85-91 (2001).
152.
van Wyk JH: Ovarian morphological changes during the annual breeding cycle of the rock lizard Agama atra (Sauria: Agamidae). Navor Nasione Museum 4:237-275 (1984).
153.
Vidal VPI, Charboissler MC, de Roolj DG, Schedl A: Sox9 induces testis development in XX transgenic mice. Nat Genet 28:216-217 (2001).
154.
Vieira S, de Pérez GR, Ramírez-Pinilla MP: Ultrastructure of the ovarian follicles in the placentotrophic andean lizard of the genus Mabuya (Squamata: Scincidae). J Morphol 271:738-749 (2010).
155.
Vonier PM, Crain DA, McLachlan JA, Guillette LJ Jr, Arnold SF: Interaction of environmental chemicals with the estrogen and progesterone receptors from the oviduct of the American alligator. Environ Health Perspect 104:1318-1322 (1996).
156.
Waits GMH, Setchell BP: Physiology of the mammalian testis, in Lemming GE (ed): Marshall's Physiology of Reproduction Reproduction in the Male, vol 2, pp 1-105 (Churchill Livingstone, London 1990).
157.
Wallace H, Badawy GMI, Wallace BMN: Amphibian sex determination and sex reversal. Cell Mol Life Sci 55:901-909 (1999).
158.
Wang Z, Pascual-Anaya J, Zadissa A, Li W, Niimura Y, et al: The draft genomes of soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan. Nat Genet 45:701-706 (2013).
159.
Warner DA, Shine R: The adaptive significance of temperature-dependent sex determination in a reptile. Nature 451:566-568 (2008).
160.
Western PS, Harry JL, Graves JA, Sinclair AH: Temperature-dependent sex determination: upregulation of SOX9 expression after commitment to male development. Dev Dyn 214:171-177 (1999).
161.
Wibbels T, Crews D: Putative aromatase inhibitor induces male sex determination in a female unisexual lizard and in a turtle with temperature-dependent sex determination. J Endocrinol 141:295-299 (1994).
162.
Wibbels T, Crews D: Steroid-induced sex determination at incubation temperatures producing mixed sex ratios in a turtle with TSD. Gen Comp Endocrinol 100:53-60 (1995).
163.
Wibbels T, Bull JJ, Crews D: Steroid hormone-induced male sex determination in an amniotic vertebrate. J Exp Zool 262:454-457 (1992).
164.
Willingham E, Crews D: Sex reversal effects of environmentally relevant xenobiotic concentrations on the red-eared slider turtle, a species with temperature-dependent sex determination. Gen Comp Endocrinol 113:429-435 (1999).
165.
Yang X, Zheng J, Xu G, Qu L, Chen S, et al: Exogenous cMHM regulates the expression of DMRT1 and ER α in avian testes. Mol Biol Rep 37:1841-1847 (2010).
166.
Yao HHC, Capel B: Temperature, genes, and sex: a comparative view of sex determination in Trachemys scripta and Mus musculus. J Biochem 138:5-12 (2005).
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