ch. 46/47 warm-up
DESCRIPTION
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:. - PowerPoint PPT PresentationTRANSCRIPT
Ch. 46/47 Warm-Up1. (Ch. 46) How do oogenesis and spermatogenesis
differ?
2. (Ch. 46) How do these hormones affect the menstrual cycle?
a) LHb) FSHc) Estrogend) Progesterone
3. (Ch. 47) Describe the process of fertilization.
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 Fertilization1. Sperm binds to receptors in zona pellucida (extracellular
matrix of egg)2. Acrosomal reaction: sperm releases hydrolytic enzymes to
digest z.p.(Sea Urchins) Depolarization of membrane: prevent other sperm from binding = fast block to polyspermy
3. Sperm + Egg Fuse4. Cortical reaction: sperm + egg fusion triggers release of Ca2+
1. cortical granules fuse with z.p. z.p. hardens to form fertilization envelope = slow block to polyspermy
5. Ca2+ release also triggers activation of the egg
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.
Organogenesis: development of 3 germ layers into organs
• Notochord – stiff dorsal skeletal rod, forms from mesoderm
• Neural plate neural tube brain and spinal cord
• Neurulation – forms hollow dorsal nerve chord
• Somites – blocks of mesoderm arranged along notochord; sign of segmentation
Embryo
Amnioticcavitywithamnioticfluid
AllantoisAmnion
Albumen
Yolk(nutrients)
Yolk sacChorion
Shell
Amniotic embryos (reptiles, birds, mammals)• Develop in fluid-filled sac w/in a shell or uterus• Amnion: fluid protects embryo – prevent
dehydration, cushions mechanical shock• Yolk : nutrients in egg• Mammalian eggs: little stored food
Patterns of development
• Cytoplasmic determinants: chemical signals such as mRNAs and transcription factors, influence pattern of cleavage
• Induction: interaction among cells that influences their fate, cause changes in gene expression
• Totipotent cells: capable of developing into all the different cell typesall cells of mammalian embryos are totipotent until
the 16-cell stage