Intro to Embryology Flashcards
duration of full term development for baby
- 38 weeks
duration of full term development for mom
- 40 weeks from LMP
name for weeks 1-2 of development
- no name
conceptus name for weeks 1-2 of development
- zygote
- morula
- blastocyst
major events for weeks 1-2 of development
- fertilization
- implantation
name for weeks 3-8 of development
- embryonic peroid
conceptus name for weeks 3-8 of development
- embryo
major events during weeks 3-8 of development
- organogenesis
name for weeks 9-38 of development
- fetal period
conceptus name for weeks 9-38 of development
- fetus
major events during weeks 9-38 of development
- growth
- maturation
development occurs at what level?
- cellular level
development starts with?
- pluripotential cells
how does development occur?
- in a series of time-locked steps in which a cell differentiates and matures
each step of development
- is induced by a message from a neighboring cell
each step only occurs if
- cell 2 has the receptors to perceive the inductive message
what happens during induction
- cell 2 becomes more differentiated
the group of cells which influence the responding cells are termed
- inducing tissue
teratogen definition
- any agent or factor that causes the body parts to develop abnormally
many teratogens will arrive via
- the mother’s blood
categories of teratogens
- medications
- substances of abuse
- chemicals
- microbes
- radiation
the study of abnormal development
- teratology
an abnormality present at birth
- birth defect
- congenital abnormality
- congenital anomaly
the developmental structural abnormality arising in the embryonic period (weeks 3-8)
- malformation
developmental structural abnormality secondary to extrinsic disruption after embryonic period (weeks 3-8)
- deformation
multiple abnormalities all developing in a sequence
- sequence
multiple abnormalities developing in no known sequence
- syndrome
normal development in pre-fertilization
- meiosis produces egg and sperm
abnormal development in pre-fertilization
- genetic abnormalities
example of an abnormal development in pre-fertilization
- downs syndrome
normal development in weeks 1,2
- mitosis
- move to uterus
- begin implantation in uterine wall
abnormal development in weeks 1,2
- not susceptible to teratogens
- secondary to inherited genetic abnormalities
- 40-50% spontaneously abort
normal development in weeks 3-8
- form organs
abnormal development in weeks 3-8
- susceptible to all types of birth defect etiologies
- most vulnerable time for embryo
major abnormal development during weeks 3-8 occurs because
- structure is only made of a few cells
- abnormal cells build abnormal organ
normal development in fetal period
- growth and maturation
abnormal development in fetal period
- susceptible to all types of birth defect etiologies
why do minor anomalies develop in the fetal period
- development of a structure is disrupted when it is nearly fully formed
another name for cranial
- rostral
the head view is called
- cranial
- rostral
the tail view is called
- caudal
directions of development
- proximal -> distal
- cranial -> caudal
what forms the placenta
- the embryo
what does maternal blood release into the placenta to go into fetal blood
- nutrients
- O2
what does the fetus release into the placenta to go into maternal blood
- wastes
is there mixing of fetal and maternal blood
- no
what does the fetus breathe
- amniotic fluid
does the fetus urinate into the amniotic fluid?
- yes
does the fetus defecate in-utero?
- no
what does the placenta function as
- fetal lungs
- kidneys
- GI tract
process of week 1 development
- fertilization
- cell division
- zygote -> morula -> blastocyst
- implantation in uterus
what does the inner cell mass eventually become?
- fetus
what does the trophoblast eventually become?
- placenta
- fetal membranes
inner cell mass in week two development
- two layers
the two layers of the inner cell mass in week two development
- epiblast
- hypoblast
what happens to the epiblast
- becomes the embryo
what happens to the hypoblast
- disappears
what appears in week 2 of development
- amniotic cavity
- primitive streak
where does the primitive streak form
- epiblast
- dorsal, caudal midline
what occurs in week 3 of development
- gastrulation
- trilaminar embryo
- somite formation
- neurulation
what occurs in gastrulation
- formation of the 3 germ layers from the primitive streak
what 3 germ layers are formed from the primitive streak?
- ectoderm
- mesoderm
- endoderm
what is the trilaminar embryo formed from?
- the 3 germ layers
somite formation
- formation of the horizontal body segments
neurulation
- formation of the nervous system
what happens to the epiblast at week 3
- mitosis of epiblast at primitive streak
- forms new cells
- migrate under epiblast layer
- form mesoderm and endoderm
- epiblast renamed ectoderm
ectoderm gives rise to
- outer layer of skin (epidermis) and teeth (enamel)
- nervous system
mesoderm gives rise to
- muscle
- bone
- connective tissues
- blood and blood vessels
- deeper layer of skin (dermis)
endoderm gives rise to
- epithelial lining of GI and respiratory tracts
mesenchyme are aggregation of
- undifferentiated cells
mesenchyme mostly comes from
- mesoderm
somite definition
- horizontal body segments composed of skin, muscle, bone, connective tissue
somites form from
how many pairs?
- paraxial mesoderm
- paired thickenings
- 35-37 pairs
each somite divides into
- dermatome
- myotome
- sclerotome
dermatome becomes
- skin dermis
myotome becomes
- muscle
sclerotome becomes
- bone
week 4 development
- organogenesis
- folding
- germ layer differentiation
- pharyngeal arches
- heart forms and begins beating
- 4 limbs begin developing
what type of folding occurs in week 4
- longitudinal
- transverse
how does the embryo begin week 4?
- flat
what does folding create
- 3D trunk
what does longitudinal folding do?
- moves the heart from the cranial into the newly formed thorax
how do cranial and caudal ends fold in longitudinal folding?
- fold ventrally
process of longitudinal folding?
- flat -> C shaped
how does transverse folding occur?
- lateral sides fold ventrally until they meet and fuse in ventral/anterior midline
what does transverse folding create?
- the GI tract
- body cavities (coelom)
- germ layer differentiation
organ structures at the beginning of week 5
- mostly present but rudimentary
organ structures by the end of week 8
- fairly mature
