Embryology - Part 1 Flashcards
During embryonic development, what event occurs on day six?
Implantation in the uterine wall
What is the gene that is expressed at the base of limbs in a zone of polarizing activity?
Sonic hedgehog (SHH) gene
The sonic hedgehog gene regulates patterning along the _____ (anterior-posterior or cranial-caudal) axis.
anterior-posterior
Name 2 genes expressed at the apical ectodermal ridge (the thickened ectoderm at the distal end of each developing limb).
Wnt-7 and FGF
What is the gene responsible for proper organization along the dorsal-ventral axis?
Wnt-7
What gene is responsible for the lengthening of limbs?
FGF
Which embryonic layer responds to products of the FGF gene?
The mesoderm
How does the FGF gene cause limbs to lengthen?
It stimulates mitosis of the underlying mesoderm
What phenotype would be seen if there was a mutation in the homeobox gene?
There would be defects in segmental organization
Day 0 of fetal life is marked by the _____ of an ovum by a sperm.
Fertilisation
What is formed when a sperm fertilizes an ovum?
The zygote
At what stage of fetal development does implantation occur?
The blastocyst stage
The embryo exists as a _____ disk during the second week of development.
Bilaminar
What two layers make up the bilaminar disk?
The epiblast and the hypoblast
During fetal development, the process of _____ occurs during the third week, which gives rise to a trilaminar disk.
Gastrulation
If an embryo has a notochord and the neural plate is beginning to form, how many weeks old is the embryo?
3 weeks old
If an embryo has a primitive streak, how many weeks old is the embryo?
3 weeks old
During what part of embryonic development does organogenesis occur?
Weeks 3-8
In an embryo, the neural tube forms from a neural plate between which days?
Days 18-21
The embryo is most susceptible to teratogens during what time period?
Weeks 3-8
During what week of development does the heart of an embryo begin to beat?
Week 4
During what week of embryonic development do the upper and lower limb buds begin to form?
Week 4
When is the first time the fetus begins to move and looks like a baby?
Week 8
During what week of development do embryos first have genitalia with either male or female characteristics?
Week 10
During embryonic development, what stage begins on day 2?
The zygote stage (2 haploid cells form a single diploid cell)
During embryonic development, what stage begins on day 3?
The morula stage (morula is latin for mulberry and occurs after the 16-cell stage)
During embryonic development, what stage begins on day 5?
The blastocyst stage (containing an outer layer of cells and an inner cell mass)
During embryonic development, what event occurs on day 6?
Implantation
What embryonic structure implants itself into the uterine wall on day 6?
The blastocyst
After the primitive streak, name three structures formed by neural precursor tissue.
Neural plate, neural crest, and neural tube
The alar plate is on the _____ side of the neural tube, while the basal plate is on the _____ side.
dorsal ; ventral
What is the function of the neurons derived from the alar plate?
Sensory
What is the function of the neurons derived from the basal plate?
Motor
What are the two cell layers that are present during the second week of embryonic development?
The epiblast and the hypoblast (remember: 2germ layers at 2weeks)
What are the two cavities that are present during the second week of embryonic development?
The amniotic sac and the yolk sac (remember: 2cavities at 2weeks)
What are the two components of the placenta that are present during the second week of development?
The cytotrophoblast and the syncytiotrophoblast
remember: 2 components of the placenta at 2 weeks
What three cell layers are present during the third week of embryonic development?
Ectoderm, mesoderm, and endoderm
remember: 3 germ layers at 3 weeks
When is the earliest you expect to see four heart chambers?
At 4 weeks
remember: 4 heart chambers at 4 weeks
When do the four limb buds appear?
At 4 weeks (remember: 4 limb buds at 4 weeks)
An embryo with three germ cell layers is known as a _____.
Gastrula
During fetal development, what cell layer of the bilaminar disk gives rise to the ectoderm?
The epiblast
During fetal development, the _____ of the bilaminar disc invaginates during the process of gastrulation to form the _____ _____.
Epiblast; primitive streak
Name two germ layers that arise from cells of the primitive streak.
Endoderm and mesoderm
During fetal development, the adenohypophysis is derived from the _____ _____, and the neurohypophysis is derived from the _____.
Surface ectoderm; neuroectoderm
During fetal development, what germ layer gives rise to the lens of the eye?
The surface ectoderm
What germ cell layer gives rise to the cells in the retina?
The neuroectoderm
During fetal development, _____ typically forms the CNS and brain, while _____ typically forms the PNS and non-neural structures nearby.
neuroectoderm; neural crest cells
During fetal development, what germ layer gives rise to the epithelial linings of the oral cavity, eye, ear and nose, and to the epidermis?
The surface ectoderm
What germ cell layer gives rise to salivary, sweat, and mammary glands?
The surface ectoderm
During fetal development, what germ layer gives rise to central nervous system neurons?
The neuroectoderm
During fetal development, the supporting cells of the central nervous system (the oligodendrocytes, the astrocytes, and the ependymal cells) are all derived from the _____, except for the microglia, which arise from the _____.
Neuroectoderm; mesoderm
During fetal development, what germ cell layer gives rise to the pineal gland?
The neuroectoderm
What cell type ultimately gives rise to the autonomic nervous system?
The neural crest cells
During fetal development, the dorsal root ganglia are derived from _____.
Neural crest cells
During fetal development, central nervous system neurons are derived from the _____, whereas the cranial nerves are derived from _____.
neuroectoderm; neural crest cells
During fetal development, central nervous system neurons arise from the _____, whereas autonomic nervous system neurons arise from _____.
neuroectoderm; neural crest cells
During fetal development, epidermal cells are derived from the _____, whereas melanocytes are derived from _____.
ectoderm; neural crest cells
During fetal development, the chromaffin cells of the adrenal medulla are derived from the _____, and the adrenal cortex is derived from the _____.
neural crest cells; mesoderm
During fetal development, the pia and arachnoid are derived from the _____, whereas the dura mater is derived from the _____.
neural crest cells; mesoderm
During fetal development, the celiac ganglia are derived from the _____.
neural crest cells
During fetal development, Schwann cells are derived from the _____, whereas oligodendrocytes are derived from the _____.
neural crest cells; neuroectoderm
During fetal development, odontoblasts are derived from the _____.
Neural crest cells (remember: odonto = teeth; think Crest toothpaste)
During fetal development, the follicular cells of the thyroid are derived from _____, whereas the parafollicular cells (C cells) are derived from the _____.
endoderm; neural crest cells
During fetal development, cartilage is generally derived from the _____, except for the laryngeal cartilage, which arises from the _____.
mesoderm; neural crest cells
During fetal development, bones are generally derived from the _____, except for the bones of the skull, which arise from the _____.
mesoderm; neural crest cells
During fetal development, what germ layer gives rise to the muscle?
The mesoderm
During fetal development, what germ cell layer gives rise to the heart?
The mesoderm
During fetal development, what germ cell layer gives rise to the blood vessels?
The mesoderm