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
Different cleavage patterns
- radial cleavage
- spiral cleavage
cleavages are symmetrical to the first
radial cleavage
radial cleavage
deuterostomes
cleavages are rotated from the first
spiral cleavage
spiral cleavage
protostomes
end product is blastula
- microlecithal
- mesolecithal
end product is blastodisc
macrolecithal
Blastula:
microlecithal
- hollow sphere
- wall is single-layered
Blastula:
mesolecithal
- hollow sphere
- wall is several layers thick
Blastula:
macrolecithal
- blastula forms as plate
- several layers thick
- on top of yolk mass
- creates the neural tube, which gives rise to the CNS
- creates the neural crest, which migrates away from the dorsal suface of the neural tube, and gives rise to a diverse set of cell types
- creates the bona fide epidermis, which covers the neural tube once it is created
neurulation
Different Stages in Neurulation
- neural plate stage
- neural groove stage
- neural tube stage
- neural crest
gives rise to the central nervous system
neural tube
migrates away from the dorsal surface of the neural tube, and give rise to a diverse set of cell types
neural crest
covers the neural tube once it is created
epidermis
thickening of the dorsal ectoderm
neural plate
produce by the infolding and pinching off of the neural plate
neural tube
what happens to the neural crest cells during neural tube formation
delamination from the roof of neural tube
4th germ layer
neural crest
Derivatives of the neural crest
- peripheral NS
- endocrine and paracrine derivatives
- epidermal pigment cells
- facial cartilage and bone
- connective tissue
majority of body structures are __ in origin
mesodermal
rapidly rounds up and separates from lateral mesoderm, forming a discrete cylinder = notochord
notochordal mesoderm
where does the notochordal mesoderm separate from to from the notochord
lateral mesoderm
mesoderm forms paired series of segmentally arranged blocks
somites
from initiation, somites posses a cavity
coelomic cavity
lateral mesoderm in Branchiostoma
- mesoderm forms somites
- initation of somites posses coelomic cavity
lateral mesoderm in Vertebrates
- no initial segmentation of mesoderm
- forms a continuous sheet wihtout central cavity
- differentiation occurs from head to tail
vertebrate embryo:
made up of somites
epimere
vertebrate embryo:
made up of nephrotome
mesomere
vertebrate embryo:
made up of lateral plate
hypomere
epimere
somite
mesomere
nephrotome
hypomere
lateral plate
Adult Derivatives from Ectoderm
- epidermis and its derivatives
- epithelial lining of mouth & anus
- cornea, lens, and retina
- NS
- epidermis’ sensory receptors
- neural crest derivatives
Adult Derivatives from Mesoderm
- notochord
- skeletal, muscular, excretory, circulatory, lymphatic, reproductive systems
- muscular layer of stomach & intestine
- dermis
- lining of body cavity
- adrenal cortex
- heart
Adult Derivatives from Endoderm
- epithelial lining of digestive tract & respiratory system
- lining of urethra, urinary bladder, & reproductive system
- liver
- pancres
- thymus
- thyroid, parathyroid glands
differentiation of adult body is caused by what?
induction
Ectodermal Derivatives in 24-hour chick embryo
- anterior neuropore
- head fold
- neural fold
- open neural plate
Mesodermal Derivatives in 24-hour chick embryo
- notochord
- somites
- unsegmented somite mesoderm
- lateral plate mesoderm
Extraembryonic regions in 24-hour chick embryo
- proamnion
- area vasculosa
- area pellucida
