Early Development

Question 1

DEVELOPMENT: Brain & Spine

day - what become what
day - form 2=1
day - form (where + signify)
day - form (1=1) = form (2) = future what

day (?-?) - form what (shape + wider) + deepened + bounded

end 3rd week - what fuse = (1) = form (1) which has cephalic vs. rest

day (?-?) - neuropore (purpose) + what closes (2) = form what which migrates how then forms what

Answer 1

• day 3-4: morula to blastocyst
• day 8: ectoderm & endoderm (bilaminar germ layer)
• day 15: form primitive streak at caudal part of BGL = start of gastrulation
• day 16: form mesoderm (trigeminal) = forms axis for embryo & induction from ectoderm (future nucleus pulposus)

day 18-20
- forms neural plate (oval; wider cranially) which is deepened by neural groove & is bounded by neural folds
- end 3rd week: neural folds fuse = neural tube (forms CNS; cephalic = brain, the rest = spine)

day 24-26:
- neuropore directs neural plate to proliferate
- ant/cranial (brain) & pos/caudal (spine) neuropore closes = neural crest
- neural crest migrates ventlat = PNS (ganglia)

Question 2

DEVELOPMENT: Brain & Spine

differentiation - endoderm (3) ecto (2) meso (3)

primary neurulation - form (2), how
secondary - form (2), what day roots

matrix cells divide to form what which is future what

clinical - anencephaly vs. bifida, hydrocephalus structure

Answer 2

DIFFERENTIATION
- endoderm: GIT, liver, lungs
- mesdoerm: CT, muscle, vascular
- ectoderm: neuro, skin

primary neurulation
- form brain & upper spine
- via neural plate

secondary neurulation
- form sacral & coccyx
- day 20-42: form spinal roots

• matrix cells divide to form neuroblast (future neuron)

CLINICAL
- anencephaly: ant neuropore not close
- bifida: pos neuropore
- hydrocephalus: blockage in sylvian aqueduct

Question 3

DEVELOPMENT: Spine & Ventricular

spine
- neural tube has (1) -> (1) of spine
- 4th to 20th week: neuroblast becomes what & forms 2 (which is ant/pos), sulcus limitans, what form ant motor root, DRG (polar)

ventricular
- CSF made where which is where
- from to, lined by what cell
- lamina terminalis (between)
- lamina > V > F > V > F > V > F > ? > ?

Answer 3

SPINE
- neural tube has neural canal which becomes central canal of spine
4th-20th week
- neuroblast becomes neuron, forms alar (pos) & basal plate (ant)
- sulcus limitans: depression between alar & basal
- ant horn = ant motor root
- DRG: unipolar (only 1 fiber exits)

VENTRICULAR
- CSF made by choroid plexus in lat ventricle
- from top to bottom of neural tube; lined with ependymal cell
- lamina terminalis: between ventricle 1 & 2
- lamina > lat ventricle > monroe > 3rd ventricle > sylvian aqueduct > 4th ventricle > foramen of lushka & magendie > central canal > subarachnoid space

Question 4

DEVELOPMENT: Brain & Spine

4th week - form (3), cervical & cephalic flexure (between)

5th week - form, telencephalic & pontine flexures (between)

10th week - CNS present

12th week - brain present

Answer 4

4th week
- form primary: rhocencephalon, procencephalon, mesencephalon
- cervical flexure (between rhom & spine), cephalic (between pro & mesen)

5th week
- form secondary: telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
- telencephalic (between tele & die), pontine (mete & mye)

10th week
- major CNS recognizable

12th week
- immature brain