Embryology Flashcards
What is a Morula?
And at how many days from Fertilisation does this occur?
Looks like a Mullberry, cells have divided and are compact, (solid ball of blastomeres).
At 3 days in the uterine tube.
In a human how long is the embryonic period?
What is the other name for this?
8 weeks
Organogenesis.
What is a Blastula? ( how many cells?)
And how many days after fertilisation does this occur?
Is when a cavity (blastocyst cavity) forms within the embryo. Minimum of 128 cells
At the 4th day
What is the sequence of events during Gestation?
6 steps starting with Gamete Formation.
Gamete Formation Fertilization Cleavage Gastrulation Organogenesis Growth (Foetal Period)
In Humans during the Embryonic Period, give the timings of germ layer development
Week 1, produces an embryo with one germ layer
Week 2, produces two germ layers
Week 3, produces three germ layers and folds those layers into a recognisable 3D form
Weeks 4-8, period of organogenesis.
What is hypertrophy?
Growth in size
What is hyperplasia?
Rapid increase in cell number
What is a teratogen?
A Teratogen is an environmental agent which can cause congenital abnormalities. Eg antibiotics (tetracycline), Vitamin L
What is a Zygote
Fused maternal and paternal pronuclei which forms the diploid zygote
When does implantation take place?
Day 6
Name 4 sites of implantation regarded as ectopic?
Uterine tube
Cervical opening of uterus
Ovary
Peritoneal cavity lining
The blastula stage embryo forms into two masses, the Embryoblast and the Trophoblast.
What is the trophoblast and what does it form?
The Embryoblast forms what?
Trophoblast is the outer cell mass and forms the placenta which supports embryonic development.
The Embryoblast (inner cell mass) forms the embryo (one layered embryo)
During Gastrulation the _______ is formed by gastrulating cells that invade and replace the entire hypo blast layer
Endoderm
Ectoderm is formed be the cells that remain in the _________
Epiblast
Mesoderm is formed by?
Gastrulating cells that migrate between the two existing layers
The Ectoderm is what layer and what does it develop into?
The outer layer
Forms epidermis and nervous tissue
What structures does the mesoderm become?
Muscle, connective tissues
The Endoderm forms what structures?
Gut. Liver, Lungs
