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  • Life and Medical Sciences  (3)
  • ASFA_2015::C::Coral reefs  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Egg transport in lizards (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 129-135 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The reproductive tracts of several species of lizards were examined to understand the events assoclated with the transport of discharged oocytes following ovulation. At the onset of the reproductive cycle the regressed ovaries and oviducts appear as inconspicuous structures pressed against the dorsal body wall. As the reproductive cycle progresses, they undergo marked changes in position and size. The oviducts migrate ventrally and surround the growing ovarian oocytes, which move anteriorly where coelomic space is more abundant and eventually press intimately against the infundibulum. When ovulation occurs the ostium is in a remarkably strategic location for directly receiving the ovulated oocytes. The virtual isolation of the ovaries from the general coelom by the encapsulating oviducts, and the intimate association of the pre-ovulatory oocytes with the infundibular ostium do not support the current concept advocating the migration of loose ova following ovulation. An alternative explanation for the “trans-coelomic migratiion of ova” is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051300202
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  • 2
    Electronic Resource
    Electronic Resource
    Reproduction and the mechanism of meiotic restitution in the parthenogenetic lizard Cnemidophorus uniparens (1971)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 139-165 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gross details of the reproductive cycle and the cytology of oogenesis were studied in 155 egg clutches produced by 69 captive individuals of the triploid parthenogenetic lizard Cnemidophorus uniparens. The mean clutch cycle lasted 23 days. The mean number of ova per clutch was 3.3, and the mean number of oocytes per right and left ovaries was 1.65 and 1.70, respectively. Comparison of the size of the oocytes at ovulation (9-10 mm) with the estimated mean duration of vitellogenesis (8.8 days) gave an average of approximately 1 mm yolk deposition per day. The mean time for the retention of eggs in the oviducts was 9.3 days. The germinal disc of the oocyte consists of a series of layers formed by the arrangement of various cytoplasmic and yolk particles in the polar region. In a mature oocyte the germinal vesicle is located immediately below the vitelline membrane and lies at the center of the germinal disc. The germinal vesicle is characterized by a dense disc-like cluster of diplotene chromosomes. Diplonema extends until near ovulation when the oocytes have attained a size of about 9 mm. Diakinesis and metaphase I occur rapidly and immediately prior to ovulation. Counts of approximately as many bivalents as there are somatic chromosomes were obtained from oocytes at diakinesis and metaphase I.The second division occurs almost immediately before or at the precise moment of ovulation. The chromosomes of the first polar body consist of dyads, of which there are as many as the triploid number of 69. A metaphase II plate obtained in polar view also revealed dyad chromosomes, of which there were approximately as many as the triploid somatic number. The second telophase is normal as evidenced by formation of the second polar body. Chromosomes from the opposing telophase plates show a monad structure. The presence of as many bivalents in the first division as the triploid somatic number of 69 indicates that the 3N condition of C. uniparens was doubled prior to meiosis. This is further supported by the occurrence of two maturation divisions each giving rise to a polar body, by the dyad structure of the chromosomes in the first polar body and the second metaphase, and by the presence of monochromosomes at telophase II. Thus, parthenogenesis in these lizards is of the meiotic type. The somatic number of chromosomes is doubled early in oogenesis presumably by a premeiotic endoduplication, and the 3N level is restored by two subsequent maturation divisions.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051330203
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  • 3
    Electronic Resource
    Electronic Resource
    Oviducal anatomy and sperm storage structures in lizards (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 7-19 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gross and histological examination of lizard oviducts was made in 11 species of the family Iguanidae, and in one species of each of the families Gekkonidae and Eublepharidae. Lizard oviducts are bound dorsally by a mesentery which is continuous with the peritoneum, and ventrally by a smooth muscle band which extends from the posterior segment of the vagina to the base of the infundibular ostium. The musculature of the vagina consists of an inner circular smooth muscle layer which is thickened posteriorly, and an outer longitudinal layer which is arranged into longitudinal folds at about the utero-vaginal transition. In iguanid lizards the vaginal mucosa is arranged into longitudinal folds that extend the entire length of the vagina. Posteriorly, the folds are high and reduced in number. Anteriorly, they decrease gradually in height and become more numerous. In Phyllodactylus homolepidurus fold height and number remain essentially constant through the vagina. Seminal receptacles in the iguanids occur principally in the anterior segment of the vagina. Receptacles in P. homolepidurus (Gekkonidae) and Coleonyx variegatus (Eublepharidae) appear to be confined to the tube between the uterus and the infundibulum. Most receptacles are located adjacent to the oviducal mesentery and to the smooth muscle band.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051190103
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  • 4
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    Variación espacio temporal del ensamble de larvas de peces coralinos en isla Gorgona, Pacífico colombiano (2017)
    Details
    Publication Date: 2021-05-19
    Description: Se describió la variación espacial y temporal del ensamble de larvas de peces asociados a formaciones coralinas en el sector oriental de isla Gorgona, Pacífico colombiano y se evaluó la relación entre la variación espacial de la abundancia y las condiciones oceanográficas locales, particularmente el campo de circulación superficial instantáneo. Se registró información oceanográfica y biológica en septiembre 2014 y febrero 2015, siguiendo una malla de 16 estaciones clasificadas en tres sectores con base en la distancia a la formación coralina de mayor extensión en el área de estudio, el arrecife coralino de La Azufrada. Se capturaron 1185 larvas de 29 especies de especies de peces asociados a formaciones coralinas. La abundancia, riqueza y diversidad del ensamble fue significativamente mayor en febrero que en septiembre, estando el ensamble dominado en septiembre por Coryphopterus urospilus (Gobiidae) y en febrero por C. urospilus y Stegastes sp. (Pomacentridae). Durante septiembre, la riqueza y diversidad de especies fue significativamente menor en el sector cercano al arrecife coralino de La Azufrada, mientras que en febrero, la riqueza y la dominancia fueron significativamente menores en la zona más externa del área de estudio. Durante septiembre, la tendencia general del campo instantáneo de circulación fue en dirección a la isla, identificando un centro de agregación de larvas en el sector del arrecife coralino La Azufrada, mientras que durante febrero fue hacia afuera de la isla registrándose una mayor abundancia en el sector externo del área de estudio. De acuerdo con la evidencia se encontró que la estructura y composición del ensamble de larvas varió de forma temporal y espacial, probablemente modulada por el efecto de patrón local de circulación superficial.
    Description: Published
    Keywords: Circulación superficial ; Arrecife Coralino ; Larvas de peces ; ASFA_2015::F::Fish larvae ; ASFA_2015::C::Coral reefs
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: pp. 55-72
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