Embryology Flashcards
What is Embryology
the branch of biology that deals with the formation, early growth and development of living organisms
in what order does the embryologic timeline of events occur?
- formation of 3 fundamental cell types
- post embryonic development
- fertilisation
- emergence of body plan
- early cell division
- fertilisation
- early cell division
- formation of 3 fundamental cell types
- emergence of body plan
- post-embryonic development
what is a zygote?
a single celled organism resulting from the fusion of male and female pro-nuclei
What are the components of the early stage blastocyst
- inner cells mass (embryo/foetus proper)
- trophoblast (placental and foetal membranes) outer layer
what are the components of the late stage blastocyst
What are the 3 germ layers of the late blastocyst
tissues derived from each primary germ layer
- ectoderm (skin epidermous, nervous system)
- mesoderm (muscle, bone, blood, vessels, kidney, gonads, skin dermis, connective tissue)
- endoderm (gut, liver, lungs, pancreas)
What is gastrulation
- a process of cellular rearrangement which involves migration, invagination and differentiation to form a tri-laminar disc
- the process that forms the 3 germ layers]
- occurs between implantation and organogenesis
- the basic body plan and primary body axis are established
what is the first visual sign of gastrulation
formation of the primitive streak and primitive node
what is the primitive streak
a midline groove in the embryo where epiblast cells migrate from the caudal end to the cranial end
what is the primitive node
the end of the primitive streak where cells build up and release transcription/growth factors
How is the Endoderm formed
formed by epiblast cells that migrate through the prmitive pit and displace the hypoblast cells
how is the mesoderm formed
by epiblast cells that migrate through the primitive pit and lie between the epiblast layer and the newly created endoderm
how is the ectoderm formed
by epiblast cells that remain in position
what is the end point of gastrulation
the bilaminar disk is transformed into a tri-laminar disk
what cells become the notochordal process
pre-notochordal cells migrating through the primitive node
what does the notochordal process form
the notochordal plate (this allows pressure equilibrium
how is the notochord formed
the notochordal plate fuses together (gives structure for the embryo to develop)
What formed the neural tube
the neural folds fusing (neurulation)
- this occurs both cranially (to form brain) and caudally (to for spinal chord)
what system is derived from the formation of the neural tube
the Central nervous system
what structures are derived from the neural crest
structures that work closely with the CNS
how is the neural crest formed
when some ectodermal cells from the neural tube migrate
what beings neurulation
the notochord
in summary, what is the ptocess of gastrulation
the change from bi-laminar disk to tri-laminar disk
what are the key stages of neurulation
5
- notochord formation
- neural ectoderm/neural plate
- neural folds
- neural tube
- neural crest
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