Presentation is loading. Please wait.

Presentation is loading. Please wait.

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

Similar presentations


Presentation on theme: "Early Vertebrate Development Early Development of Mammals Early Development of Birds…if we have time."— 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 – 1 st Meriodionally – 2 nd 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 Zona pellucida prevents embryo from attaching to oviduct wall. Trypsin like protease: releases embryo from ZP.

8 Mammalian Gastrulation 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


Download ppt "Early Vertebrate Development Early Development of Mammals Early Development of Birds…if we have time."

Similar presentations


Ads by Google