development of the peripheral nervous system

what causes differentiation of the ectoderm

BMP morphogen

what happens to ectoderm at no BMP

neural plate develops

what happens to ectoderm at high BMP

epidermis (skin) develops

what does chordin and noggin repress

BMP

how is the neural crest specified

intermediate levels of BMP

what happens to the neural crest if there is too much BMP

lack of both neural plate and neural crest

what happens to neural crest in complete absence of BMP

loss of both epidermis and neural crest

where are ectodermal cells loacted

junction of neural plate and epidermis

where is the neural crest

surrounding the neural plate

what tissues does the neural crest contribute too

PNS, melanocytes, facial structure, adrenal medulla, and some structures of the heart

when does specification and differentiation of neural crest tissues happen

prior to migration

what do ectodermal cells exposed to an intermediate level of BMP activate

sox10

what distinguishes neural crest from other ectodermal cells

expression of sox10, pax3, and pax7

steps of development of the neural crest

1. specification and differentiation into neural crest

2. further differentiation into destination fates

3. migration to destination

where do cranial neural crest cell migrate

into the head and the pharyngeal arches

what does the cranial neural crest give rise to

melanocytes of the head, all facial bones, bones of the ear, nerves of head and neck, cartilage within neck, and glands of the neck (thyroid, parathyroids, and thymus)

what do cardiac neural crest cells give rise to

melanocytes, nerves and ganglia of thorax, ventricular septum, outflow tract, and septum that separates aorta from pulmonary arteries

what do thorax neural crest cells give rise to

dorsal root ganglia, PNS of the digestive system, adrenal medulla, and melanocytes of the trunk and limbs

how do neural crest cells migrate

cells undergo EMT (changes to cadherin expression and cytoskeletal changes)

what causes change in cytoskeleton during neural crest migration

Rho

what causes repression of cadherin expression during neural crest migration

Snail

what type of signals determine the path of neural crest cell migration

local signals

what signaling is produced for melanoblasts

attractive molecules called ephrins produced by the dermis

Epidermis secretes SCF

NC cells destined to become melanocytes express the corresponding receptor (Kit)

Somites secrete Wnt and neurotrophin

NC cells destined to become dorsal root ganglia express corresponding receptors

Adrenal cortex secretes BMP

NC cells destined to become adrenal medulla express BMP receptors

Gut expresses GDNF

NC cells destined to become enteric PNS express corresponding receptor (Ret)

which tissues might be affected by a defect in differentiation of the cardiac neural crest

melanocytes, nerves and ganglia, cartilage, and the heart

Outflow tract of heart, thoracic PNS, thoracic pigmentation

which tissues might be affected by a defect in proliferation of cranial neural crest

cranial neurons, facial bone and cartilage, pharyngeal arches

Facial structure, hearing, cranial pigmentation, function of thyroid, parathyroid, and/or thymus

which tissues might be affected by migration of the trunk neural crest

Enteric PNS, adrenal medulla function, pigmentation

what are defects in neural crest development called

neurocristopathies

neurocristopathies involving pigmentation

partial loss-of-function mutations or heterozygosity in Kit (the receptor for SCF) can disrupt proliferation, survival, and migration of melanoblasts, leading to pigmentation aberrations (such as piebaldism). NC cells fated to become melanoblasts express MITF prior to migration

additional neurocristopathies

Treacher Collins syndrome and Hirschsprung’s disease

what is Hirschsprung’s disease caused by

genetic mutation that disrupts GSNF Ret signaling, thereby preventing NC cells from migrating into the intestines to build the gut PNS

what is Treacher Collins syndrome caused by

genetic mutation that disrupt survival and/or proliferation of cranial neural crest

why are defects in development of the neural crest are fairly common

neural crest development is very complex (many steps must survive migration and migrate to the proper location)

why id domestication linked to changes in face shape and pigmentation

all linked to neural crest