Video Experimental Relacionado
Updated: May 6, 2026
10:59
An ex-ovo Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications
Published on: October 24, 2010
22.7K
Los embriones arthrodire devonianos y el origen de la fertilización interna en los vertebrados
John A Long1, Kate Trinajstic, Zerina Johanson
1Museum Victoria, PO Box 666, Melbourne 3001, Victoria, Australia. jlong@museum.vic.gov.au
Nature
|February 27, 2009
Resumen
Los embriones fósiles descubiertos en peces Arthrodira revelan que la fertilización interna y el nacimiento vivo (viviparidad) eran comunes en los primeros vertebrados de mandíbula. Esto desafía las suposiciones anteriores sobre las antiguas estrategias de reproducción de los vertebrados.
Área de la Ciencia:
- Paleontología Paleontología.
- Zoología de los vertebrados Zoología de los vertebrados.
- Biología evolutiva Biología evolutiva.
Sus antecedentes:
- La evidencia de la biología reproductiva es escasa en el registro fósil.
- Descubrimientos anteriores identificaron embriones en ptictodóntidos (Placodermi), lo que sugiere viviparidad fuera del grupo de corona Gnathostomata.
- Placodermi es una clase extinta de peces blindados.
Objetivo del estudio:
- Para informar sobre el descubrimiento de embriones en especímenes de Arthrodira.
- Proporcionar evidencia de la fecundación interna en este diverso grupo de placodermos.
- Para investigar las estrategias reproductivas de Incisoscutum ritchiei de la Formación Gogo del Devónico Superior.
Principales métodos:
- Análisis fósil de ejemplares de Incisoscutum ritchiei.
- Análisis comparativo esquelético de las fajas pélvicas en placodermos y condríctios.
- Interpretación filogenética de las similitudes anatómicas.
Principales resultados:
- Se descubrieron embriones dentro de ejemplares de Arthrodira (Incisoscutum ritchiei).
- La evidencia sugiere fertilización interna y viviparidad en este grupo.
- Las fajas pélvicas en Incisoscutum y arthrodires phyllolepid indican aletas pélvicas fueron utilizados en la cópula.
- Las similitudes esqueléticas se atribuyen a la evolución convergente (homoplasia).
Conclusiones:
- La fertilización interna y la viviparidad estaban muy extendidas en los primeros gnathostomes.
- Los hallazgos amplían nuestra comprensión de la evolución reproductiva de los vertebrados.
- Este estudio proporciona la primera evidencia de la reproducción utilizando la fertilización interna en Arthrodira.
Videos de Conceptos Relacionados
01:38Fertilization
68.9K
During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ovary, and travels into the fallopian tubes. The process requires several key steps: 1) sperm present in the genital tract must locate the egg; 2) once there, sperm need to release enzymes to help them burrow through the protective zona pellucida of the egg; and 3) the membranes of a single sperm cell and egg must fuse, with the sperm...
68.9K
01:33Cleavage and Blastulation
42.5K
After a large-single-celled zygote is produced via fertilization, the process of cleavage occurs while zygotes travel through the uterine tube. Cleavage is a mitotic cell division that does not result in growth. With each round of successive cell division, daughter cells get increasingly smaller.
42.5K
01:56Gastrulation
53.0K
Gastrulation establishes the three primary tissues of an embryo: the ectoderm, mesoderm, and endoderm. This developmental process relies on a series of intricate cellular movements, which in humans transforms a flat, “bilaminar disc” composed of two cell sheets into a three-tiered structure. In the resulting embryo, the endoderm serves as the bottom layer, and stacked directly above it is the intermediate mesoderm, and then the uppermost ectoderm. Respectively, these tissue strata...
53.0K
02:39The Angiosperm Life Cycle
62.7K
Plants have a life cycle split between two multicellular stages: a haploid stage—with cells containing one set of chromosomes—and a diploid stage—with cells containing two sets of chromosomes. The haploid stage is the gamete-producing gametophyte, and the diploid stage is the spore-producing sporophyte.
62.7K
01:07Development of Blood Vessels
2.0K
The development of the vascular system in a fetus is a complex and intricate process that begins as early as 15 to 16 days post-conception. This process starts outside the embryo, specifically in the mesoderm of the yolk sac, chorion, and connecting stalk. Approximately two days later, the formation of blood vessels occurs within the embryo itself.
The initial formation of this system is facilitated by the small amount of yolk present in the ovum and yolk sac. Blood vessels originate from...
The initial formation of this system is facilitated by the small amount of yolk present in the ovum and yolk sac. Blood vessels originate from...
2.0K
01:15Development of the Sexual Organs in the Embryo and Fetus
5.6K
Development of the reproductive organs in an embryo starts from a bipotential state. This means the early embryo can develop either male or female reproductive organs. The formation of these organs begins with the growth of gonadal ridges that arise from the intermediate mesoderm during the fifth week of development.
Near the gonadal ridges, two duct systems are present: the mesonephric ducts (Wolffian ducts) and paramesonephric ducts (Müllerian ducts). These ducts form the basis for the...
Near the gonadal ridges, two duct systems are present: the mesonephric ducts (Wolffian ducts) and paramesonephric ducts (Müllerian ducts). These ducts form the basis for the...
5.6K