Embryology Flashcards
What is an oocyte?
-Ovum, egg
-Female germ cell
What is sperm?
Male germ cell
What is a zygote?
Cell resulting from union of oocyte and sperm at fertilisation
What are blastomeres?
Early embryonic cells
What is a morula?
Solid mass of 12-32 blastomeres
What is a blastocyst?
Stage where morula has entered uterine cavity and blastocystic cavity develops within
What is a gastrula?
Stage after trilaminar embryonic disc formation
What is a neurula?
Stage after gastrula when neural tube forms
What is an embryo?
Developing human during embryonic stage (to end of 8th week
What is a fetus?
Period from 9th week to birth
Label this diagram:
Label this diagram:
What happens on day 4?
What happens on day 5 and 6?
What becomes the embryo?
Inner cell mass
What does trophoblast become?
Embryonic part of placenta
What does synctiotrophoblast do?
Determines what crosses into the placenta
Label this diagram:
What forms on day 8?
Bilaminar disc
What is the position of the layers in the bilaminar disc?
-Ectoderm = outer
-Mesoderm = middle
-Endoderm = inner
What happens on days 8 and 9?
What happens on days 11-13?
Exocoleomic cyst = remnant of primary yolk sac
Label this diagram of day 13:
What happens here and on what day?
Formation of umbilical cord
What happens on week 3?
-Gastrulation
-Bilaminar disc becomes trilaminar disc
-Called gastrula
What has happened to form the primitive streak?
As the ectoderm grows, a folding occurs along the caudal midline which creates the primitive streak
What are the two ends?
What is happening in this diagram?
Label and describe when this is:
What does the ectoderm differentiate into?
-Epidermis of skin, hair and nails
-Mammary, sweat and sebaceous glands
-Central nervous system
-Peripheral nervous system
-Pituitary gland
-Teeth enamel
-Lens of eye and inner ear parts
-Sensory epithelium of nose, ear and eye
What does the endoderm differentiate into?
What does the mesoderm form?
Describe the formation of the notochord:
What happens on week 4?
Neurulation
What are the first and second steps of neuralation?
What are the third and fourth steps of neurulation?
Explain neurulation:
Explain the clinical relevance of neurulation:
What does this show?
-Varying degrees of spina bifida
-Sac protruding from spinal column - sometimes spinal cord and nerves in spinal sac damaged
When does differentiation of mesoderm occur?
Simultaneous to neuralation
Label this diagram:
What does it show?
Differentiation of mesoderm
What does the paraxial mesoderm differentiate into?
Describe somites:
-First appear in future occipital region of embryo
-Develop craniocaudally
-Precursor populations giving rise to important structures of the vertebral body
What do somites give rise to?
What does the intermediate mesoderm differentiate into?
-Urogenital system:
-Kidneys
-Gonads
-Respective duct system
What does the lateral mesoderm split into?
-Two layers
-Somatic (parietal) layer mesoderm - outer layer
-Splanchnic (visceral) layer mesoderm - second layer
What do the somatic and splanchnic layer mesoderms do?
-Somatic - covers inside of the chest and abdominal walls
-Splanchnic - covers organs in the thorax and abdomen
What happens on week 4?
Embryo folding
What does this show?
Describe it:
-Embryo folding
-Folding of both planes occur simultaneously
What does this show?
Describe the process:
Summarise what happens in lateral folding:
Label this diagram:
What does it show?
Lateral folding
Label this diagram of functions of body cavities:
What are they a result of?
Lateral folding
What does this show?
Describe it:
Cephalo-caudal folding (1st stage of ventral folding)
What does this show?
Cephalo-caudal folding (2nd stage of ventral folding)
Summarise what happens on weeks 1 and 2:
Summarise what happens on weeks 3 and 4:
Summarise what happens on weeks 5 to end of 8:
