Embryo Exam I Flashcards
What is the definition of fertilization?
fusion of pronucleus (sperm) with pronucleus (ovum) to form zygote
What is the site of fertilization?
ampulla of uterine tube
What are the phases of fertilization?
capacitation, acrosomal reaction, penetration (of 3 layers), zona reaction (no one else can go inside)
What layer helps the implanting blastocyst?
trophoblast cells
What is the site of implantation?
in the posterior superior wall of uterus
Describe the placental barrier in early pregnancy and late pregnancy.
Early-
syncytiotrophoblast (outermost layer near maternal blood)
cytotrophoblast (middle)
connective tissue then fetal endothelium
Late-
syncytiotrophoblast (outermost layer near maternal blood)
fetal endothelium
Which layer of placental barrier disappears between early and late pregnancy? Why does the layer that remains, remain?
cytotrophoblast disappears
syncytiotrophoblast remains because produced HcG (keeping placenta lined)
Describe gastrulation.
3rd week. 3 primary germ layers
ectoderm, endoderm, mesoderm (from epiblast)
Describe the three germ layers.
ectoderm. mesoderm. endoderm.
Describe ectoderm.
brain and spinal cord, sympathetic ganglia
epidermis, hair, nails, glands of skin
Describe endoderm.
epithelial lining and glands of digestive and respiratory tracts
Describe mesoderm.
Notochord-
Somite-
intermediate mesoderm-
lateral plate mesoderm (somatic mesoderm and splanchnic mesoderm)-
Notochord- nucleus pulposus of IV discs (future vert. column)
Somite- vertebrae and ribs, dermatome, dermis of dorsal body region, myotome -trunk and limb musculature
intermediate mesoderm- kidneys, gonads
lateral plate mesoderm (somatic mesoderm and splanchnic mesoderm)-
somatic- dermis of ventral body region, parietal serosa, connective tissues of limbs (bones, joints, ligaments)
splanchnic- wall of digestive and respiratory tracts (except epithelial lining) visceral serosa, heart, blood vessels
What happens at week four?
four pharyngeal (branchial arches)
CAP
Clefts = ectoderm
Arches= mesoderm
Pouches =endoderm
At the golden arches, childen tend to…
Chew (1st) - V (trigeminal) Smile (2nd) - VII (Facial) Stylish (3rd) - IX (Glossopharyngeal... stylopharyngeal) Swallow (4th) Speak (6th) -X (Vagus)
What are the muscles of mastication?
temporal, masseter, medial and lateral pterygoids
What is in the neumonic for pharyngeal pouches?
Ear, Tonsils, Bottom To Top
1- tympanic (middle ear) vaity, auditory (eustachian) tube,
2- palatine tonsils, tonsillar fossa
3- inferior parathyroid gland, thymus (comes out of tongue)
4- superior parathyroid gland ultimobranchial body (parafollicular cells of thyroid gland)
What happens if the 2nd 3rd and 4th pharyngeal clefts are obliterated by overgrowth of 3nd arch and 4th arch toward each other forming a cervical sinus… if this persists what forms?
branchial cyst or fistula
What must degenerate for blastocyst implantation to occur?
zona pellucida
