Postlab 3 - Embryology of Frog and Chick Flashcards
- study of embryos, encompasses the study of the development of animals
- deals with ontogenetic development rather than phylogenetic development
embryology
individual organism development
ontogenetic development
evolutionary history of an organism
phylogenetic development
Stages in Ontogenetic Development
- gametogenesis
- fertilization
- cleavage
- gastrulation
- organogenesis
- growth and differentiation
- formatio and maturation of sperm and egg
- 1N = haploid
gametogenesis
- fusion of sperm and egg to produce a zygote
- 2N = diploid
fertilization
mitotic cell divisions of early embryo, eventually forming a blastula or blastodisc
cleavage
what is eventually formed during cleavage
blastula or blastodisc
migration and displacement of a single layer of surface cells, still mitotically active, so that three distinct layers are formed
gastrulation
continuous masses of cells in the 3 germ layers become split into smaller group of cells, each of which will develop into a specific organ or body parts of the animal
organogenesis
growth of organ rudiments and acquisition of structure and physiochemical properties allowing them to function as adult structures
growth and differentiation
Classification of eggs based on amount of yolk
- megalecithal
- mesolecithal
- microlecithal
- huge amount of yolk
- birds, reptiles, bony fish
megalecithal
megalecithal example
- birds
- reptiles
- bony fishes
- moderate amount of yolk
- amphibians
mesolecithal
mesolecithal example
amphibians
- very little yolk
- amphioxus, mammals
microlecithal
microlecithal example
- amphioxus
- mammals
Classification of eggs based on distribution of yolk
- isolecithal
- telolecithal
- centrolecithal
- yolk evenly distributed
- sea urchins, amphioxus, humans
isolecithal
isolecithal example
- sea urchins
- amphioxus
- humans
- yolk distributed in a gradient
- reptiles, fish, birds, amphibians
telolecithal
telolecithal example
- reptiles
- fish
- birds
- amphibians
- yolk concentrated in the center of the egg
- most arthropods
centrolecithal
centrolecithal example
most arthropods
what is important in classifying cleavage patterns
position of upper cells relative to lower cells