In this chapter you will: Describe the acrosomal reaction; describe the cortical reaction; distinguish among meroblastic cleavage and holoblastic cleavage; compare the formation of a blastula and gastrulation in a sea urchin, a frog, and a chick; list and explain the functions of the extraembryonic membranes. | Ch. 46/47 Warm-Up (Ch. 46) How do oogenesis and spermatogenesis differ? (Ch. 46) How do these hormones affect the menstrual cycle? LH FSH Estrogen Progesterone (Ch. 47) Describe the process of fertilization. Chapter 47 Animal Development What you must know: The events that occur when a sperm contacts an egg What occurs in cleavage, gastrulation, and organogenesis Two structures derived from each germ layer Mammalian Fertilization Sperm binds to receptors in zona pellucida (extracellular matrix of egg) Acrosomal reaction: sperm releases hydrolytic enzymes to digest . (Sea Urchins) Depolarization of membrane: prevent other sperm from binding = fast block to polyspermy Sperm + Egg Fuse Cortical reaction: sperm + egg fusion triggers release of Ca2+ cortical granules fuse with . . hardens to form fertilization envelope = slow block to polyspermy Ca2+ release also triggers activation of the egg Fertilization in mammals Cleavage: rapid mitotic cell division Zygote cytoplasm partitioned into smaller cells (blastomeres) Solid ball of cells = morula Blastula (hollow ball of cells) filled with fluid (blastocoel) Blastocyst (human) Gastrulation: rearrange cells to form 3-layered embryo w/primitive gut Three Embryonic Germ Layers* Ectoderm Mesoderm Endoderm Skin, nails, teeth Lens of eye Nervous system (brain, spinal cord) Skeletal, muscular systems Notochord Excretory, circulatory Reproductive system Blood, bone, muscle Epithelial linings of digestive, respiratory, excretory tracts Liver, pancreas * For AP Test, you should know at least 2 derivatives of each germ layer. Future ectoderm Key Future mesoderm Future endoderm Archenteron Blastocoel remnant Ectoderm Mesoderm Endoderm Yolk plug Yolk plug Gastrula Blastocoel shrinking Blastocoel Dorsal tip of blastopore CROSS SECTION Animal pole Dorsal lip of blastopore Vegetal pole Blastula SURFACE VIEW Gastrulation in a frog embryo Future ectoderm Epiblast Migrating cells (mesoderm) YOLK Hypoblast Endoderm Primitive . | Ch. 46/47 Warm-Up (Ch. 46) How do oogenesis and spermatogenesis differ? (Ch. 46) How do these hormones affect the menstrual cycle? LH FSH Estrogen Progesterone (Ch. 47) Describe the process of fertilization. Chapter 47 Animal Development What you must know: The events that occur when a sperm contacts an egg What occurs in cleavage, gastrulation, and organogenesis Two structures derived from each germ layer Mammalian Fertilization Sperm binds to receptors in zona pellucida (extracellular matrix of egg) Acrosomal reaction: sperm releases hydrolytic enzymes to digest . (Sea Urchins) Depolarization of membrane: prevent other sperm from binding = fast block to polyspermy Sperm + Egg Fuse Cortical reaction: sperm + egg fusion triggers release of Ca2+ cortical granules fuse with . . hardens to form fertilization envelope = slow block to polyspermy Ca2+ release also triggers activation of the egg Fertilization in mammals Cleavage: rapid mitotic cell division Zygote cytoplasm .
