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Rams-Pociecha I, Mizia PC, Piprek RP. Histological Analysis of Gonadal Ridge Development and Sex Differentiation of Gonads in Three Gecko Species. BIOLOGY 2023; 13:7. [PMID: 38248438 PMCID: PMC10813461 DOI: 10.3390/biology13010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/16/2023] [Accepted: 12/19/2023] [Indexed: 01/23/2024]
Abstract
Reptiles constitute a highly diverse group of vertebrates, with their evolutionary lineages having diverged relatively early. The types of sex determination exemplify the diversity of reptiles; however, there are limited data regarding the gonadal development in squamate reptiles. Geckos constitute a group that is increasingly used in research and that serves as a potential reptilian model organism. The aim of this study was to trace the changes in the structure of developing gonads in the embryos of three gecko species: the crested gecko, leopard gecko, and mourning gecko. These species represent different families of the Gekkota infraorder and exhibit different types of sex determination. Gonadal development was examined from the formation of the earliest gonadal ridges through the development of undifferentiated gonadal structures, sex differentiation of gonads, and the formation of testicular and ovarian structures. The study showed that the gonadal primordia of these three gecko species formed on the most dorsally located surface of the dorsal mesentery, and both the coelomic epithelium and the nephric mesenchyme contributed to their development. As in other reptile species, primordial germ cells settled in the gonadal ridges, and the undifferentiated gonad was composed of a cortex and a medulla. Ovarian differentiation started with the thickening of the gonadal cortex and proliferation of germ cells in this region. A characteristic feature of the developing gecko ovaries was the thickened crescent-shaped cortex on the medial and ventral surfaces of the ovaries. The ovarian medulla also grew and exhibited diverse tendencies to form cords. In the leopard gecko, advanced cord-like structures with lumens were observed in the ovaries, which were not seen in the crested gecko. Testicular differentiation was characterized by cortical thinning and the disappearance of germ cells in this region. In the medulla, the development of distinct cords with early lumen formation was noted. A characteristic feature of embryonic gonads was their growth in a horizontal plane. In this study, gonadal development was characterized by several features that are shared by geckos and other reptiles, along with features that are specific only to geckos.
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Affiliation(s)
- Izabela Rams-Pociecha
- Department of Comparative Anatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Poland; (I.R.-P.); (P.C.M.)
- Doctoral School of Exact and Natural Sciences, Jagiellonian University, 30-348 Krakow, Poland
| | - Paulina C. Mizia
- Department of Comparative Anatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Poland; (I.R.-P.); (P.C.M.)
- Doctoral School of Exact and Natural Sciences, Jagiellonian University, 30-348 Krakow, Poland
| | - Rafal P. Piprek
- Department of Comparative Anatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Poland; (I.R.-P.); (P.C.M.)
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2
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Mezzasalma M, Brunelli E, Odierna G, Guarino FM. Evolutionary and Genomic Diversity of True Polyploidy in Tetrapods. Animals (Basel) 2023; 13:ani13061033. [PMID: 36978574 PMCID: PMC10044425 DOI: 10.3390/ani13061033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/02/2023] [Accepted: 03/10/2023] [Indexed: 03/14/2023] Open
Abstract
True polyploid organisms have more than two chromosome sets in their somatic and germline cells. Polyploidy is a major evolutionary force and has played a significant role in the early genomic evolution of plants, different invertebrate taxa, chordates, and teleosts. However, the contribution of polyploidy to the generation of new genomic, ecological, and species diversity in tetrapods has traditionally been underestimated. Indeed, polyploidy represents an important pathway of genomic evolution, occurring in most higher-taxa tetrapods and displaying a variety of different forms, genomic configurations, and biological implications. Herein, we report and discuss the available information on the different origins and evolutionary and ecological significance of true polyploidy in tetrapods. Among the main tetrapod lineages, modern amphibians have an unparalleled diversity of polyploids and, until recently, they were considered to be the only vertebrates with closely related diploid and polyploid bisexual species or populations. In reptiles, polyploidy was thought to be restricted to squamates and associated with parthenogenesis. In birds and mammals, true polyploidy has generally been considered absent (non-tolerated). These views are being changed due to an accumulation of new data, and the impact as well as the different evolutionary and ecological implications of polyploidy in tetrapods, deserve a broader evaluation.
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Affiliation(s)
- Marcello Mezzasalma
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende, Italy
- Correspondence: (M.M.); (E.B.)
| | - Elvira Brunelli
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende, Italy
- Correspondence: (M.M.); (E.B.)
| | - Gaetano Odierna
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126 Naples, Italy (F.M.G.)
| | - Fabio Maria Guarino
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126 Naples, Italy (F.M.G.)
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Stöck M, Dedukh D, Reifová R, Lamatsch DK, Starostová Z, Janko K. Sex chromosomes in meiotic, hemiclonal, clonal and polyploid hybrid vertebrates: along the 'extended speciation continuum'. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200103. [PMID: 34304588 PMCID: PMC8310718 DOI: 10.1098/rstb.2020.0103] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2021] [Indexed: 12/15/2022] Open
Abstract
We review knowledge about the roles of sex chromosomes in vertebrate hybridization and speciation, exploring a gradient of divergences with increasing reproductive isolation (speciation continuum). Under early divergence, well-differentiated sex chromosomes in meiotic hybrids may cause Haldane-effects and introgress less easily than autosomes. Undifferentiated sex chromosomes are more susceptible to introgression and form multiple (or new) sex chromosome systems with hardly predictable dominance hierarchies. Under increased divergence, most vertebrates reach complete intrinsic reproductive isolation. Slightly earlier, some hybrids (linked in 'the extended speciation continuum') exhibit aberrant gametogenesis, leading towards female clonality. This facilitates the evolution of various allodiploid and allopolyploid clonal ('asexual') hybrid vertebrates, where 'asexuality' might be a form of intrinsic reproductive isolation. A comprehensive list of 'asexual' hybrid vertebrates shows that they all evolved from parents with divergences that were greater than at the intraspecific level (K2P-distances of greater than 5-22% based on mtDNA). These 'asexual' taxa inherited genetic sex determination by mostly undifferentiated sex chromosomes. Among the few known sex-determining systems in hybrid 'asexuals', female heterogamety (ZW) occurred about twice as often as male heterogamety (XY). We hypothesize that pre-/meiotic aberrations in all-female ZW-hybrids present Haldane-effects promoting their evolution. Understanding the preconditions to produce various clonal or meiotic allopolyploids appears crucial for insights into the evolution of sex, 'asexuality' and polyploidy. This article is part of the theme issue 'Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)'.
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Affiliation(s)
- Matthias Stöck
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries - IGB (Forschungsverbund Berlin), Müggelseedamm 301, 12587 Berlin, Germany
- Amphibian Research Center, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Dmitrij Dedukh
- Institute of Animal Physiology and Genetics, Laboratory of Fish Genetics, The Czech Academy of Sciences, 277 21 Libechov, Czech Republic
| | - Radka Reifová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, Prague 2, 128 00, Czech Republic
| | - Dunja K. Lamatsch
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria
| | - Zuzana Starostová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, Prague 2, 128 00, Czech Republic
| | - Karel Janko
- Institute of Animal Physiology and Genetics, Laboratory of Fish Genetics, The Czech Academy of Sciences, 277 21 Libechov, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, 701 03 Ostrava, Czech Republic
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4
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Murakami Y, Hayashi F. Molecular discrimination and phylogeographic patterns of clones of the parthenogenetic gecko
Lepidodactylus lugubris
in the Japanese Archipelago. POPUL ECOL 2019. [DOI: 10.1002/1438-390x.1030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Yuki Murakami
- Department of BiologyTokyo Metropolitan University Tokyo Japan
| | - Fumio Hayashi
- Department of BiologyTokyo Metropolitan University Tokyo Japan
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5
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Verdú-Ricoy J, Matla T, Gregory M, Lambiris A, Jordaan A, Zhao Z, Heideman N. A comparative analysis of testicular sperm morphology in fossorial and surface-living skinks in South Africa. ACTA ZOOL-STOCKHOLM 2018. [DOI: 10.1111/azo.12249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Joaquín Verdú-Ricoy
- Department of Zoology & Entomology; University of the Free State; Bloemfontein South Africa
| | - Tankiso Matla
- Department of Zoology & Entomology; University of the Free State; Bloemfontein South Africa
| | | | | | - Adriaan Jordaan
- Department of Zoology & Entomology; University of the Free State; Bloemfontein South Africa
| | - Zhongning Zhao
- Department of Zoology & Entomology; University of the Free State; Bloemfontein South Africa
| | - Neil Heideman
- Department of Zoology & Entomology; University of the Free State; Bloemfontein South Africa
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Spangenberg V, Arakelyan M, Galoyan E, Matveevsky S, Petrosyan R, Bogdanov Y, Danielyan F, Kolomiets O. Reticulate Evolution of the Rock Lizards: Meiotic Chromosome Dynamics and Spermatogenesis in Diploid and Triploid Males of the Genus Darevskia. Genes (Basel) 2017; 8:E149. [PMID: 28538689 PMCID: PMC5485513 DOI: 10.3390/genes8060149] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/10/2017] [Accepted: 05/18/2017] [Indexed: 11/16/2022] Open
Abstract
Knowing whether triploid hybrids resulting from natural hybridization of parthenogenetic and bisexual species are fertile is crucial for understanding the mechanisms of reticulate evolution in rock lizards. Here, using males of the bisexual diploid rock lizard species Darevskia raddei nairensis and Darevskia valentini and a triploid hybrid male Darevskia unisexualis × Darevskia valentini, we performed karyotyping and comparative immunocytochemistry of chromosome synapsis and investigated the distribution of RAD51 and MLH1 foci in spread spermatocyte nuclei in meiotic prophase I. Three chromosome sets were found to occur in cell nuclei in the D. unisexualis × D. valentini hybrid, two originating from a parthenogenetic D. unisexualis female and one from the D. valentini male. Despite this distorted chromosome synapsis and incomplete double-strand breaks repair in meiotic prophase I, the number of mismatch repair foci in the triploid hybrid was enough to pass through both meiotic divisions. The defects in synapsis and repair did not arrest meiosis or spermatogenesis. Numerous abnormal mature spermatids were observed in the testes of the studied hybrid.
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Affiliation(s)
- Victor Spangenberg
- N.I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia.
| | - Marine Arakelyan
- Department of Zoology, Yerevan State University, Yerevan 0025, Armenia.
| | - Eduard Galoyan
- Zoological Museum, Lomonosov Moscow State University, Moscow 125009, Russia.
| | - Sergey Matveevsky
- N.I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia.
| | - Ruzanna Petrosyan
- Department of Zoology, Yerevan State University, Yerevan 0025, Armenia.
| | - Yuri Bogdanov
- N.I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia.
| | - Felix Danielyan
- Department of Zoology, Yerevan State University, Yerevan 0025, Armenia.
| | - Oxana Kolomiets
- N.I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia.
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7
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Spermatogenesis of Amphisbaena silvestrii(Boulenger, 1902): First Report for Amphisbaenidae. J HERPETOL 2017. [DOI: 10.1670/15-154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Mezzasalma M, Andreone F, Glaw F, Petraccioli A, Odierna G, Guarino FM. A karyological study of three typhlopid species with some inferences on chromosome evolution in blindsnakes (Scolecophidia). ZOOL ANZ 2016. [DOI: 10.1016/j.jcz.2016.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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9
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Trifonov VA, Paoletti A, Caputo Barucchi V, Kalinina T, O’Brien PCM, Ferguson-Smith MA, Giovannotti M. Comparative Chromosome Painting and NOR Distribution Suggest a Complex Hybrid Origin of Triploid Lepidodactylus lugubris (Gekkonidae). PLoS One 2015; 10:e0132380. [PMID: 26148117 PMCID: PMC4492922 DOI: 10.1371/journal.pone.0132380] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 06/13/2015] [Indexed: 11/24/2022] Open
Abstract
Parthenogenesis, unisexuality and triploidy are interesting but poorly studied phenomena occurring in some reptile species. The mourning gecko (Lepidodactylus lugubris) represents a complex of diploid and triploid parthenogenetic mostly all-female populations (males occur quite rarely) widely distributed in coastal areas of the Indian and Pacific Oceans. Here, we study karyotypes of a male and two female L. lugubris (LLU) triploid individuals (3n = 66) using comparative painting with Gekko japonicus, Hemidactylus turcicus and H. platyurus chromosome specific probes to visualize the homologous regions and to reveal genus specific rearrangements. Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs). Our results suggest that the karyotype of L. lugubris underwent a chromosome fission and a fusion after its divergence from a common ancestor of the Gekko-Hemidactylus group. The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals. It seems that three different bisexual populations might have contributed to the origin of this triploid parthenogenetic population. We postulate that the heterozygosity in NOR localization is maintained in the triploid clone studied by the absence of recombination as described in whiptail lizards. The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.
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Affiliation(s)
- Vladimir A. Trifonov
- Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia
- Novosibirsk State University, Novosibirsk, Russia
- * E-mail:
| | - Alessio Paoletti
- Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, Ancona, Italy
| | - Vincenzo Caputo Barucchi
- Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, Ancona, Italy
- Consiglio Nazionale delle Ricerche, Istituto di Scienze Marine Sezione Pesca Marittima,Ancona, Italy
| | - Tatiana Kalinina
- Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia
- Novosibirsk State University, Novosibirsk, Russia
| | - Patricia C. M. O’Brien
- Cambridge Resource Centre for Comparative Genomics, University of Cambridge, Cambridge, United Kingdom
| | - Malcolm A. Ferguson-Smith
- Cambridge Resource Centre for Comparative Genomics, University of Cambridge, Cambridge, United Kingdom
| | - Massimo Giovannotti
- Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, Ancona, Italy
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10
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Park CJ, Ha CM, Lee JE, Gye MC. Claudin 11 inter-sertoli tight junctions in the testis of the korean soft-shelled turtle (Pelodiscus maackii). Biol Reprod 2015; 92:96. [PMID: 25761591 DOI: 10.1095/biolreprod.114.117804] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 03/03/2015] [Indexed: 11/01/2022] Open
Abstract
Expression of claudin 11 (CLDN11), a tight junction (TJ) protein, was examined in the Korean soft-shelled turtle (Pelodiscus maackii) testis. Spermatogenesis began during the breeding season and peaked at the end of the breeding season. Spermiation started in summer and peaked in autumn. The deduced amino acid sequence of P. maackii CLDN11 was similar to those of avian and mammalian species. During the nonbreeding season when spermatogenesis and testosterone production were active, testicular Cldn11 levels were high. In the seminiferous epithelium, strong, wavy CLDN11 strands parallel to the basement membrane delaminate the spermatogonia, and early spermatocytes are in the open compartment. Otherwise, CLDN11 was found beneath the early spermatocytes and in the Sertoli cell cytoplasm. Punctate zonula occludens 1 (ZO-1) immunoreactivity was found within the CLDN11 strands parallel to the basement membrane or at the outermost periphery of the seminiferous epithelium close to the basal lamina. During the breeding season, when circulating testosterone levels and spermatogenic activity was low, testicular CLDN11 level was lower than those during the nonbreeding season. CLDN11 was found at apicolateral contact sites between adjacent Sertoli cells devoid of the postmeiotic germ cells. At this time, lanthanum tracer diffused to the adluminal compartment of seminiferous epithelium. In cultured testis tissues, testosterone propionate significantly increased the level of Cldn11 mRNA. In P. maackii testis, CLDN11 participates in the development of the blood-testis barrier (BTB), where the CLDN11 expression was coupled with spermatogenic activity and circulating androgen levels, indicating the conserved nature of TJs expressing CLDN11 at the BTB in amniotes.
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Affiliation(s)
- Chan Jin Park
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, Korea
| | - Cheol Min Ha
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, Korea
| | - Jae Eun Lee
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, Korea
| | - Myung Chan Gye
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, Korea
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11
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Al-Amri IS, Mahmoud IY, Waring CP, Alkindi AY, Khan T, Bakheit C, Al-Mawali KM. The reproductive cycle of the male house gecko, Hemidactylus flaviviridis, in relation to plasma steroid concentrations, progesterone receptors, and steroidogenic ultrastructural features, in Oman. Gen Comp Endocrinol 2013; 187:23-31. [PMID: 23524273 DOI: 10.1016/j.ygcen.2013.02.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 01/24/2013] [Accepted: 02/23/2013] [Indexed: 11/17/2022]
Abstract
The annual testicular cycle of the house gecko Hemidactylus flaviviridis in Oman was studied. Plasma testosterone (T), estradiol (E2) and progesterone (P) concentrations were measured using a sensitive HPLC-MS/MS detection technique. The ultrastructural steroidogenic features in Sertoli and Leydig cells, which were the major source of steriodogenesis, were examined, using transmission electron microscopy (TEM). In addition, progesterone receptors (PR) were examined throughout the testicular cycle, using an immunohistochemical technique. The steroidogenic ultrastructural features were characterized by the presence of smooth endoplasmic reticulum (SER) in the form of cisternal whorls and tubular cisternae, presence of swollen vesiculated mitochondria, and association between SER, mitochondria and lipid droplets. The rise in plasma steroid concentrations was closely associated with the development of the ultrastructural features and PR expression in Leydig and Sertoli cells. During the active phase (November-May), there was a significant rise in plasma steroid concentrations (P<0.05) related to well developed steroidogenic features and strongly expressed PR. During the quiescent phase (June-August) there was a significant decline in plasma steroid concentrations, undeveloped steroiodogenic features and weakly expressed PR. The Renal Sexual Segment (RSS) was fully developed during the active phase. The data provides strong evidence that these ultrastructural steroidogenic features were related to the plasma sex steroid concentrations during the testicular cycle.
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Affiliation(s)
- Issa S Al-Amri
- Department of Biological Sciences and Chemistry, University of Nizwa, Nizwa, Oman.
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12
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Rheubert JL, Siegel DS, Venable KJ, Sever DM, Gribbins KM. Ultrastructural description of spermiogenesis within the Mediterranean Gecko, Hemidactylus turcicus (Squamata: Gekkonidae). Micron 2011; 42:680-90. [PMID: 21543229 DOI: 10.1016/j.micron.2011.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/10/2011] [Accepted: 03/11/2011] [Indexed: 11/30/2022]
Abstract
We studied spermiogenesis in the Mediterranean Gecko, Hemidactylus turcicus, at the electron microscope level and compared to what is known within other Lepidosaurs. In H. turcicus germ cells are connected via cytoplasmic bridges where organelle and cytoplasm sharing is observed. The acrosome develops from merging transport vesicles that arise from the Golgi and subsequently partition into an acrosomal cap containing an acrosomal cortex, acrosomal medulla, perforatorium, and subacrosomal cone. Condensation of DNA occurs in a spiral fashion and elongation is aided by microtubules of the manchette. A nuclear rostrum extends into the subacrosomal cone and is capped by an epinuclear lucent zone. Mitochondria and rough endoplasmic reticulum migrate to the posterior portion of the developing germ cell during the cytoplasmic shift and the flagellum elongates. Mitochondria surround the midpiece as the anlage of the annulus forms. The fibrous sheath begins at mitochondrial tier 3 and continues into the principal piece. Peripheral fibers associated with microtubule doublets 3 and 8 are grossly enlarged. During the final stages of germ cell development spermatids are wrapped with a series of Sertoli cell processes, which exhibit ectoplasmic specializations and differing cytoplasmic consistencies. The results observed here corroborate previous studies, which show the conservative nature of sperm morphology. However, ultrastructural character combinations specific to sperm and spermiogenesis seem to differ among taxa. Further studies into sperm morphology are needed in order to judge the relevance of the ontogenic changes recorded here and to determine their role in future studies on amniote evolution.
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Affiliation(s)
- Justin L Rheubert
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA 70402, USA.
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13
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Gamble T. A review of sex determining mechanisms in geckos (Gekkota: Squamata). Sex Dev 2010; 4:88-103. [PMID: 20234154 PMCID: PMC2855288 DOI: 10.1159/000289578] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 07/27/2009] [Indexed: 11/19/2022] Open
Abstract
Geckos are a species-rich clade of reptiles possessing diverse sex determining mechanisms. Some species possess genetic sex determination, with both male and female heterogamety, while other species have temperature-dependent sex determination. I compiled information from the literature on the taxonomic distribution of these sex determining mechanisms in geckos. Using phylogenetic data from the literature, I reconstructed the minimum number of transitions among these sex determining mechanisms with parsimony-based ancestral state reconstruction. While only a small number of gecko species have been characterized, numerous changes among sex determining mechanisms were inferred. This diversity, coupled with the high frequency of transitions, makes geckos excellent candidates as a model clade for the study of vertebrate sex determination and evolution.
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Affiliation(s)
- T. Gamble
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minn., USA
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