DLA 5 Flashcards
Explain week one of fertilization?
- capacitation
- Acrosome reaction
- Fusion of the membranes between both sex cells
What happens during capacitation?
Removal of the seminal proteins from the surface and penetration through the corona radiata
What happens during acrosome reaction?
Release of acrosomal enzymes and penetration through the zona pellucida
What is the normal site of fertilization?
The ampula of the fallopian tube
How is the normal diploid number gained?
The fusion of the male and female pronuclei
What is the developing embryo called after the formation of 16-32 blastomeres?
Morula (day 3)
What are blastomeres defined as?
The production of identical daughter cells
Explain the formation of the blastocyst?
This occurs after the morula enters the uterus
A blastocystic cavity forms within the morula
The blastomeres separate into two separate parts:
- centrally located cells (embryo) located at the embryonic pole
- peripheral cells (trophoblast)
Where does the blastocyst normally implant itself?
Posterior wall of body of uterus close to the fundus
6 days
How does the blastocyst attach to the endometrium?
By the syncytiotrophoblast
When the blastocyst attaches to the endometrium.. what two layers does the trophoblast differentiate into?
an inner cytotrophoblast
an outer syncytiotrophoblast
What does the inner cytotrophoblast do?
Makes new cells and mitotically active
What does the syncytiotrophoblast?
invades and secretes
human chorionic gonadotrophin (HCG)
can be used to determine pregnancy early
What enables the burrowing of the blastocyst?
mass of cells or syncytium at the embryonic pole erode
Explain the embryonic disk?
a flat, circular bilaminar plate of cells
What are the two layers of the embryonic disk?
The epiblast and the hypoblast
Explain the epiblast?
the thicker layer, consisting of high columnar
cells. Eventually forms the three definitive germ layers
Explain the hypoblast?
consisting of small cuboidal cells. Becomes part of the yolk sac
What are the three germ layers?
endoderm, ectroderm, and mesoderm
What does the endoderm develop into?
epithelial linings
What does the ectoderm develop into?
Nervous tissue
What are the three subtypes of mesoderm?
- lateral
- intermediate
- paraxial
What does the mesoderm develop into?
Lateral - heart, spleen, adrenals
intermediate - urogenital organs
paraxial - bone, muscle, skin
