Presentation on theme: "Today’s Objective: 2.1 The student will list the germ layers and their derivatives The student will be able to sequence the stages of animal development."— Presentation transcript:
1 Today’s Objective: 2.1The student will list the germ layers and their derivativesThe student will be able to sequence the stages of animal development
2 EmbryologyStudy of development from fertilized egg until all major organ systems are formed.
3 Sperm must penetrate gel coat of an egg. FertilizationSperm must penetrate gel coat of an egg.
8 Stages of Egg Activation Egg membrane wraps microvilli around sperm headSperm is drawn into egg cytoplasmFormation of fertilization membraneVitelline layer lifts off of the eggVitelline layer strengthens and thickensCortical changes take place (gray crescent in amphibians)
9 Fast Electrical Block to Multiple Fertilizations
10 Other changes with fertilization Formation of animal poleFormation of vegetal pole
17 Initial Cleavage Eggs are microlecithal Cleavage is holoblastic Cleavage (2 cell, 4 cell, etc.) initially forms the morula
18 Blastula Formation Interior of morula is pulled away Forms blastocoel Hollow ball = BLASTULA (layer is one cell thick)
19 Gastrula formation - morphogenesis Invagination begins at vegetal pole (blastopore – becomes the anus)Archenteron is formed – embryonic gutEmbryo lengthens – forms anterioposterior axisCoelom devlops from outpockets of archenteronMouth formed when gut breaks through anterior wall