Exam 1: Neurogenesis

conception to day 14

day 15-8th week

nervous system development is necessary

end of 8th week until birth

development of nervous system from ectoderm

in the pre-embryonic stage in the fallopian tube

starts and continue while zygote moves down the tube

stage of morula to blastula

< 8 cells for division

8 cells for division

solid sphere of cells is formed in the cavity and implants into the endometrium, thus, creating the blastocyst

during implantation, the inner cell mass develops into the embryonic disc, and three layers are formed (ectoderm, mesoderm, and endoderm)

outer layer of the sphere and becomes the fetal contribution of the placenta

organs

CNS, PNS, skin, nails, sensory epithelia of eyes, ears, and nose

muscles, skeleton, cardiovascular system, kidneys, spleen, gonads, and adrenal glands

gut, liver, pancreas, thyroid, and respiratory system

all organs and systems develops more fully

nervous system develops nad myelination begins

18th day: thickened part of ectoderm (neural plate)

20th day: edges fold to create the neural groove

22nd day: edges of neural tube come together and fuse at the center

on 22nd day, the tube is located in the cervical area of the embryo

rostral and caudal

persists until the 24th and 26th days

24th day

26th day

failure to close rostral neuropore, resulting in deficient development of the rostral brain structures (cerebrum)

failure to close caudal neuropore, resulting in spina bifida (incomplete development of caudal nervous system - lumbar and sacral spinal cord)

formation of brain and structures

forms spinal cord

ectoderm cells that remain outside the neural tube

dorsal clumps form sensory ganglia (DRG) while ventral clumps form sympathetic trunk ganglia

formed by the 28th day and expanded in 3 points with vesicles

prosencephalon (forebrain)

mesencephalon (middle brain)

rhombencephalon (hindbrain)

bending between the hindbrain and spinal cord in the area od the cervical cord

bending between the mesencephalon and hindbrain

subdivision of the prosencephalon at the 5th week and leads to the formation of cerebral hemisphere and basal ganglia

subdivision of the prosencephalon at the 5th week and develops into the thalamus, hypothalamus, optic nerves, and tracts