1 / 22

Early Vertebrate Development

Early Vertebrate Development. Early Development of Mammals Early Development of Birds…if we have time. Long and Winding Road…. Both Egg and Sperm have to overcome physical barriers. Ampulla - site of fertilization. Cleavage in Mammals. Rotational cleavage 1 st Meriodionally

chynna
Download Presentation

Early Vertebrate Development

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Early Vertebrate Development • Early Development of Mammals • Early Development of Birds…if we have time.

  2. Long and Winding Road… • Both Egg and Sperm have to overcome physical barriers. • Ampulla- site of fertilization.

  3. Cleavage in Mammals • Rotational cleavage • 1stMeriodionally • 2nd one divides meriodionally, one divides equatorially • Asynchrony • No real Mid-Blastula Transition.

  4. Compaction • Division of early embryo up to 8 cell stage is loosely arranged. • At 8 cell stage, cells form tight interactions and divide into 16 cell morula. • Internal Cells= Internal Cell mass (ICM) • Most external cells become trophoblast.

  5. Early Cells in Mammalian Embryo • Totipotent • Pluripotent

  6. Cavitation. • Trophoblast cells secrete fluid into Morula: blastocoel • Trophoblast Na+ pumps are activated by oviduct cells.

  7. Hatching of Mammalian Blastula • Zonapellucida prevents embryo from attaching to oviduct wall. • Trypsin like protease: releases embryo from ZP.

  8. MammalianGastrulation • Mother provides nutrients • The reliance of embryo on Mother has resulted in fetal organs • Chorion • Hypoblast/epiblast • Germ disc • Amniotic cavity

  9. Mammalian Gastrulation: Primative Groove

  10. Extraembryonic Membranes • Trophoblast cells make up cytotrophoblast and syncytiotrophoblast. • Trophoblasts and Uterine tissue: Placenta

  11. Axis specification in Mammals • Two signaling centers • Node • Anterior Visceral Endoderm(AVE) • Work together to form anterior region. • Notochord: dorsal infolding of small ciliated cells • AVE: visceral endoderm migrates forward. • Antagonists of Nodal • Lefty-1; Cerberus • Nodal activates expression of posterior genes; Lefty-1 and Cerberus blocks this activity

  12. Axis Specification: Anterior-Posterior positioning • FGF and Retinoic acid gradients. • Ultimately leads to differential expression of Hox genes

  13. Anterior-Posterior Axis: Hox Code

  14. Retinoic Acid and Hox Gene Expression

  15. Dorsal-Ventral and Left-Right Axes • DV axis formation: Poorly characterized. • Left-right axis formation: Nodal and Pitx2

  16. Early Development of Birds: Cleavage

  17. Gastrulation: Birds • The Hypoblast • The primative streak

  18. The Primitive Streak

  19. Primitive Streak: Molecular mechanisms of migration

  20. Regression of Primitive streak

  21. Axis specification in Birds • Gravity and PMZ

  22. Left Right Axis

More Related