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Gametogenesis
 

Gametogenesis

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    Gametogenesis Gametogenesis Presentation Transcript

    • GAMETOGENESISDR. JOSÉ LUIS ESPINOZA V.
    • The first phase in this process involves the developing gonad by primordial germ cellsfrom which the germ cells develop. The subsequent process, by which the maternal andpaternal gametes are produced from the primordial germ cells, is referred to asgametogenesis.The primordial germ cells are the predecessors of the female and male gametes.
    • • During and after their migration, the primordial germ cells proliferate by mitoses.• The female (XX) and male (XY) primordial germ cells become engaged in sex-specific differentiation of the gonads and become surrounded by somatic cells• They are now referred to as oogonia and spermatogonia, respectively.• These cells undergo further proliferation before they enter gametogenesis and, thus, meiosis.
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    • GAMETOGENESIS• Proceso de transformación a través del cual estas células se convierten en unidades altamente especializadas: – Células sexuales • Óvulos • Espermatozoides
    • • Gametogenesis includes meiosis, to allow for recombination of genetic material and for reduction of the number of chromosomes from the diploid to the haploid complement, and cytodifferentiation, to achieve the cellular structure characteristic of the female or male gamete.
    • CONSECUENCIAS DE LA MEIOSIS
    • ÓVULO VS ESPERMATOZOIDE
    • ESPERMATOGENESIS• Divisiones celulares en túbulo seminífero (espermatocitogénesis)• Cambios morfológicos (espermiogénesis)• De la periferia al centro
    • • En esta fase se elimina el citoplasma por desplazamiento del mismo hacia la pieza terminal de la cola originando la llamada gota citoplasmática.
    • • El espermatozoide adquiere la capacidad de mover el flagelo en su tránsito por el epidídimo, pero el movimiento empieza después de la eyaculación.• Este proceso es conocido como la activación del esperma.
    • CICLO DEL EPITELIO SEMINIFERO (ciclo espermatogénico)• En la pared del túbulo seminífero hay asociaciones de células
    • SEMEN• Suspensión celular liquida o semigelatinosa que contiene los espermatozoides y las secreciones de las glándulas accesorias
    • PLASMA SEMINAL (J Reprod Immunol. 2002 Jan;53)• Fracción liquida del semen• Las vesículas seminales del bovino secretan una familia de proteínas (proteínas del plasma seminal; PPS)• Con la eyaculación las PPS se unen a la superficie del espermatozoide• Interactúan con factores de capacitación bovina (heparina y HDL)• Las PPS estimulan la pérdida de colesterol y fosfolípidos de la membrana espermática – Paso importante en el proceso de capacitación
    • • Killian et al. (1993) reported the presence of four “fertility- associated proteins” in the Holstein seminal plasma, one of them later identified as osteopontin (OPN).• The same protein, detected in accessory sex gland fluid, was associated with fertility indexes of dairy bulls.• This protein is expressed in the ampullae, seminal vesicles and possibly the epididymis, as well as in the oviduct.• In the seminiferous tubules, where it is synthesized by Sertoli and germ cells, OPN is potentially involved in cell adhesion and migration.
    • • The potential influence of seminal proteins on male reproduction came to attention because of the studies showing that their expression is associated with breeding scores of dairy bulls, beef bulls and horses. – Prostaglandin D synthase – Oseopontin