Fetal Development Flashcards
What is an acrosome?
Develops during maturation of the sperm. It contains digestive enzymes that help sperm across the corona radiata.
What is capacitation?
Process that sperm goes through in crypts of female genital tract where it is fed and prepared to make it responsive to female environment.
The ovum is surrounded by what 2 walls?
Corona Radiata and Zona Pellucida.
What is Cortical Reaction?
When the Zona Pellucida blocks enzymes of any other sperm, preventing them from attaching.
What is the pre-embryonic stage?
From fertilisation to implantation.
What is the embryonic stage?
From implantation to week 8.
What is the fetal stage?
From week 9 to birth.
What 4 steps is the pre-embryonic stage made up of?
Zygote - Day 2 Embryo (cleavage) - Morula (3 days) - Blastocyst (10 days)
What is the bilaminar disc?
The embryoblast differentiates into two layers when implantation occurs; the epiblast and hypoblast.
What is Gastrulation?
The process of the bilaminar disc evolving into a trilaminar disc. It puts an end to the pre-embryonic state (at day 15).
What does the epiblast differentiate into during gastrulation?
Ectoderm. This forms skin, hair, nails etc.
What does the hypoblast differentiate into during gastrulation?
Endoderm. This forms glandular cells and lining of digestive and respiratory tracts.
What is the Primitive Streak?
A channel created by epiblast cells migrating inwards. More cells migrate through it between the 2 layers of bilaminar disc, forming the mesoderm layer.
What does the Mesoderm form?
Muscles, bones, blood and urogenital glands.
What is the notochordal process?
The creation of a tube that in the mesoderm by the ectoderm. It temporarily connects the amniotic cavity and yolk sac, providing pressure equilibrium.
What is the notochord?
The result of the closing of the tube created during notochordal process. Acts as a midline for tissues to follow in trilaminar disc and forms major structure of embryo.
What is embryonic folding?
Occurs during the 4th week when trilaminar disc fold on horizontal and median planes, forming the embryo.
What is the Primitive Gut?
Formed from the fusion of the endoderm to midline. It differentiates into foregut, midgut and hindgut.
By what day is embryo folded and the end of embryonic state?
Day 25
What is neurulation?
The formation of the neural tube which forms into the brain and spinal cord of the embryo.
What is dextral looping?
During cardiac development, the atrium and ventricle are created by twisting rightward.
What is the window of implantation?
The embryo sends chemical signals to tell the endometrium to be responsive to implantation for a very short period of time.
What does the trophoblast differentiate into?
Cytotrophoblast and syncytiotrophoblast.
What are chorionic villi?
Finger-like projections of the syncytiotrophoblast which feed the pregnancy.
What does the Cytotrophoblast form?
The Chorionic Membrane (Chorion).
What are the steps of fertilisation?
- Penetration of Corona Radiata
- Acrosome Reaction
- Cortical Reaction
- Gamete Fusion
- Meiosis Completion
What are the steps of Gastrulation?
- Primitive Streak
- Mesoderm Development
- Notochordal Process
- Notochordal Plate
- Notochord Fusion
