Development Flashcards
What is embryonic development?
stage during which all major organs systems are established
What is the post-embryonic development stage?
during which growth and refinement of such systems takes place
What are the 5 steps of development?
Cell proliferation, cell growth, cell differentiation, pattern formation, morphogenesis
What is cell proliferation and how is dynamic equilibrium maintained?
The number of cells increase through cell division. Dynamic equalibrium is maintained though constant, programmed apoptosis and proliferation / differentiation of progenitors
What is cell growth?
Proliferating cells undergo cycles of cell division and growth.
What is hyperplasticity?
Increase in cell number, too many cell divisions. Increased tissue size b/c too many cells
What is hypertrophy?
An increase in cell size leading to a bigger tissue although cell number is the same
What is differentiation?
A progenitor cells receives stimuli from the environment and responds by acquiring new morphological/structural and functional characteristics
Can a cell go back or dedifferentiate after differentiating?
No, differentiation is unidirectional
What is terminal differentiation?
The stage at which a cell can no longer differentiate further.
What is pattern formation?
The process whereby cells become organized into tissues, organs and organ systems
What is morphogenesis?
The development of morphological characteristics. It entails the last 4 steps/processes.
What happens on days 1- 14 of embryonic development?
Initial cell divisions take place
What happens on day 14 of embryonic development?
Grastulation: three distinct tissues begin to form and there are no more embryonic stem cells
What happens on days 19- 21 of embryonic development?
Neurulation: beginning of the future nervous system.
What happens on days 21 - 24 of embryonic development?
Beginning of future head, neck, mouth and nose
What happens on weeks 3-8 of embryonic development?
Beginning of organ formation
What happens on week 8 of embryonic development?
Fetus is formed
When is the ovum released?
Day 14 of the menstrual cycle
What is the polidy of the ovum and sperm?
They are both haploid cells that fuse together to make a diploid cell
What part of the sperm enters the oocyte?
Just the pronucleus. The pronuclei from the sperm and pronuclei from the egg are initially separated but when they fuse and give the zygote
What is the morula?
Loosely packed ball of cells
Describe the 16-cell morula stage. What is the first differentiation in mammalian development?
Compaction, the separation of trophoblast from inner cell mass.
What are the 2 types of cells in compaction and what do they do?
Inner non-polarized cells and external polarized cells. Ezternal cells from tight junctions to seal the inner cells off and the internal cells from gap junctions to exchange substances.
What do the external polarized cells give rise to? Internal non-polarized?
External gives rise to extra-embryonic and placenta and internal gives rise to the embryo.
Describe the 32-cell stage, what happens?. What is the first differentiation in mammalian development?
Cavitation happens and a blastocyst is formed.
What is the blastocoele?
Fluid filled cavity of the blastocyst
When does the blastocyst attach to the uterine wall?
6-7 days after fertilization
What is gastrulation?
The process in which a gastrula develops from a blastula by the inward migration of cells.
What are the 3 primordial germ layers that make up the gastrula?
Endoderm, mesoderm, ectoderm
What marks the beginning of gastrulation? And the ingression of cells give rise to what germ layers?
The primitive streak and the ingression of cells that will give rise to endoderm and mesoderm
What is neurulation? What does it also induce?
The folding process in vertebrae embryos which includes the transformation of the neural plate into the neural tube. Also induves the development of mesoderm into distinct sections that will give rise to distinct organs/body parts
By the end of what trimester have most organs started their development?
End of first trimester
