ommatidia

- heterozygotes for a loss of function mutation in Pax-6

paired box

buldges from the diencephalon of the prosencephalon that extend to the head ectoderm which becomes the lens placode

neural tube and epidermal thickening that forms the transparent lens to allow light on retina; does not form neurons

originated from the outer layer of the optic cup, produces melanin

the ability of a cell to respond to extrinsic factors.  In this example the ability of the epidermal cells to respond to the cells of the eye field.

the process by which eye field initiates the formation of the lens in the epidermis, and then the lens initiates the form formation of the retina from the eye field.

the process by which eye field initiates the formation of the lens in the epidermis, and then the lens initiates the form formation of the retina from the eye field.

the two layered invagination of the combined optic vesicle and lens placode 

- anterior most portion of neural tube which develops into the forebrain

2nd portion of anterior NT which forms into the midbrain responsible for motivation, movement and depression

3rd portion of anterior NT which forms into the hindbrain; the cerebrum and the medulla oblongata (involuntary activities: breathing)

- anterior portion of prosencephalon which becomes cerebral hemispheres

- posterior portion of prosencephalon which becomes optic vesicles

secondary vesicle stemming from the rhombencephalon which develops into the medulla oblongata

secondary vesicle derived from the anterior rhombencephalon which develops into the cerebellum and pons

mid portion of brain responsible for fine tuning movement and language.

- superior most portion of brain responsible for all voluntary actions, learning, memory, smell, and language

precursor of neuron, come from neural stem cells, detach from NT after cell division

paracrine factor responsible for formation of ventral morphology of the developing NT, derived from floor plate and notochord, help create D/V axis of NT

transcription factors found in the epidermis which initiate roof plate formation and D/V axis of NT.

- derived from the medial hinge point cells on the ventral surface of the NT; secrete shh

initiated by the presence of BMP4 and 7 from the epidermis cells dorsal to the NT, the dorsal NT cells become the roof plate and express TGF-B.

a layer of rapidly dividing neural stem cells one layer thick with nuclei at varying distances from the NT lumen based upon their stage of mitotic division.

-  the point at which a neuroblast divides from the neura-epithelial stem cell, it contains higher amounts Notch receptors than the remaining stem cell and will not divide again.  Stem cell retains a greater portion of Par-3.

cortical mantle or intermediate zone, a layer of cells which form around the ventricular zone containing cells which differentiate into neurons and glial cells (grey matter)

portion of the NT which is in contact with the lumen and cerebrospinal fluid where asymmetrical division occurs

zone filled with axons of mantle cells (white matter) covered in glial cells

- in cerebellum, germinal cell layer outside the marginal zone at boundary of NT where neuroblasts reside 

zone within the mantle formed by neuroblasts which have migrated back towards the ventricular zone after being exposed to BMPs in the external granule layer and becoming granule cells.

produced by ventricular zone, they are the major cell type of the cerebellum.  secrete shh sustaining granule cell division; huge # of dendrites and connection to ventricular zone.  only output neurons of cerebellar cortex

elaborate points of connection found on purkinje neurons just above bulblike cell body: like a tree

neuroblasts from mantle migrate on glial processes through white matter to form grey matter layer on surface of the brain

dorsal region of spinal cord which receives sensory input

neurons which transmit info TO the CNS   Alar region

- neurons which transmit info FROM the CNS

Notch/Delta: determine a neuronal fate

achaete/scute: bHLH transcription factors, targets of notch

transmembrane protein which receives signal from notch, which in turn downregulates its own delta production and stops cell from being proneural

transmembrane signalling protein that acts as ligand to Notch

a group of cells which are equally competent to be induced into differentiating into specific cells 

equivalent neighboring cells which signal one another causing downregulation of signaling from some cells thus creating cell differentiation.

- mutation causing lack of extracellular matrix protein Reelin which is required to allow neuroblasts to bind with glial cells resulting in 

- extracellular matrix protein required for binding of neuroblasts to glial cells, highly expressed during cell migration to cortex, loss of fxn results in disorganized cortex

- the fine branching extensions of the neuron that pick up impulses from other cells

- glial cell which wraps around developing axons and insulates the cells and increases cell longevity

specialized cell membrane of the oligodendrocyte (in CNS) and Schwann Cell (in PNS) which insulates the axons at intervals

- stem cells at the base of the epidermis which produce daughter cells which migrate exteriorly.  After differentiating they become keratinocytes which are bound tightly together, have ceased metabolic and transcription.

- rope like protein in alpha helices; major component of skin, hair and nails.

- the major pigment producing cells of skin and hair; originates in neural crest, migrates to epidermis, hair follicles, eye and ear.

pigment compound made by melanocytes, can be black, brown, blonde or red.

- bottom most layer of epidermis; mitotically active; contains keratinocyte stem cells and melanocytes

layer of mitotically active keratinocytes just above the basal layer

2nd most exterior layer of epidermis comprised of non dividing, not fully flattened keratinocytes

most external layer of epidermis comprised of flattened, keratin filled, non dividing keratinocytes

external body layer comprised of 4 layers originating from the ectoderm

- layer of mesenchyme tissue just deep to the epidermis

self signalling ligands which create powerful self induction cycles

- excessive exfoliation of epidermal cells

portion of hair visible above skin

proliferation of epidermal cells induced by signaling

mesenchyme cells induced into aggregation at the formation of the epidermal placode

medulla, cortex, cuticle (hair)

- oil producing glands derived from the epidermis which migrate into the outer root sheath

oil produced by the sebaceous glands which lubricates hair shaft and skin

thin, closely spaced hair of human embryo that is typically shed before birth

short silky hair produced before adolescence and sometimes after follicles revert; may remain on "hairless" parts of body (ie eyelids and forehead)

cycle of growth 

a signaling pathway which, along with Wnt, is crucial for placode formation but also enhances the placode inhibitor Dkk

excessive facial hair in women

excessive hair for age, sex, or ethnicity

monomer of melonin which produces black and brown color

monomer of melonin which produces red color

NC cells which differentiate into cranial nerves, cartilidge, connective tissue, teeth, ears, jaw, pharyngeal arches

dorsal root ganglia (sensory neuron ganglia), autonomous nervous system, adrenal medulla, melanocytes

proteins within the posterior portion of the sclerotome which inhibit the migration of ventrally moving NC cells causing them to move through the anterior portion of the sclerotome, and promotes the migration of dorsally migrating melanocytes.

bone formation directly from mesenchyme; no cartilidge intermediate state

committed bone precursor cell

- a collagen proteoglycan secreted by the osteoblasts capable of binding CA

osteoblasts embedded in the osteoid matrix

membrane of cells surrounding bone, inner surface become osteoblasts and lay down layers of bone

disorder which fails to produce pigments in some regions in the body

phenotype due to incomplete migration and differentiatioin of nc cells contributing to melanocytes.

process of somite formation: fissure formation (separation of somites), periodicity, epithelialization, specification, differentiation

central region of trunk mesoderm, form notochord and transient organs

somatic mesoderm flanking the notochord on both sides, form somites, to make muscle, vertebrae, ribs, and connective tissue,  anterior most region becomes head mesoderm

lateral to paraxial mesoderm, forms urogential system, including kidneys and gonads as well as adrenal gland

furthest from notochord, forms heart, blood vessels, blood cells and circulatory system, lining of body cavities, pelvic and limb skeleton (not muscles)

prechordal plate mesoderm - 

- whorls of cells, originally mesenchyme which have migrated through the primitive streak and become the precursors of somites

sectioned off piece of paraxial mesoderm

gene expressed which correlates with the formation of the boundary between somites.

- gene activated by notch activity which plays a role in fissure creation and somite separation

proteins induced by Mesp products which repel one another and establish separation of somite from presomatic mesoderm

ventral/lateral compartment of individual somite which forms vertebrae and rib cartilage

dorsomedial and ventrolateral compartments of individual somite which forms musculature of the back, rib cage and ventral body wall

muscle precursor cells which develop at the most lateral and proximal edges of the myotome, forming a second layer of cells which develop into the abaxial muscles and primaxial muscles respectively

central portion of the dermamyotome which becomes the dermis of the back

fibronectin

myogenesis

myotubes

mesenchyme cells turn to cartilage which turns into bone, sclerotome contributes

RTKs, domains of receptors which phosphorylate one another once dimerized

ligand binds - dimerize - mutual phosphorylation - grb2 - sos - ras - raf - mek - map - tf activated

ligand binds - dimerize - mutual phosphorylation - plc - ip3 - mobilize CA from ER

-  cell-cell communication allowing cells to sense their environment and adjust cell fates accordingly to make complete structure

circular induction which propagates further induction (eg. FGF8 stimulates FGF10 which stimulates FGF8)

patterns the A/P limb axis, small cluster at dorsal-posterior of limb bud where SHH is produced

interdigital necrotic zone

Hx mutation, over  expression of SHH resulting in excess blocking of Gli3 and thus extra digits, all posterialized. 

- initial layer of epidermis which covers wound

- wound epidermis transforms into aec 

- reverting differentiated cells to undifferentiated cells

fibroblast cells which become the progenitor cells for new limb formation