ECTODERM, MESODERM, ENDODERM (copy)

Ectoderm

• the outermost germ layer in animals.

• gives rise to the skin, nervous system, and sense organs. In the early embryo, it is the first layer to form from a fertilized egg.

Epiblast

What is 1?

Hypoblast

What is 2?

Intraembryonic mesoderm

What is 1?

Endoderm

What is 2?

Ectoderm

What is 1?

Mesoderm

What is 2?

Endoderm

What is 3?

Mesoderm

The notochord must arise from what germ layer?

Chordata

an embryonic midline structure common to all members of the phylum ________, providing both mechanical and signaling cues to the developing embryo

Notochord

an embryonic midline structure common to all members of the phylum Chordata, providing both mechanical and signaling cues to the developing embryo

Ectoderm

What is 1?

Mesoderm

What is 2?

Endoderm

What is 3?

Notochord

What is 4?

Neural tube

What is 5?

Amnios

What is 6?

oropharengeal membrane

what is 1?

notochordal process

what is 2?

cloacal membrane

what is 3?

• skin

• nervous system

What does the ectoderm form?

• muscles

• bones

• notochord

what does the mesoderm form?

• gut lining

• internal organs

what does the endoderm form?

• prechordal plate

• chordamesoderm

Some mesodermal cells migrate forward toward the embryo’s midline. These cells become:

Prechordal plate

This mesodermal cell becomes the anterior organizer

Chordamesoderm

This mesodermal cell becomes the precursor of the notochord

Chordamesoderm

This extends forward from the primitive node (Hensen’s node in birds/mammals)

Intraembryonic mesoderm

What is 1?

Extraembryonic mesoderm

What is 2?

Endoderm

What is 3?

Notochord

What is 4?

Sonic hedgehog (Shh)

Notochord secretes factors like ____ to induce the neural plate and pattern the somites (future vertebrae, ribs, muscles)

• Ectoderm

• Mesoderm

• Endoderm

Gastrulation forms these germ layers

Neural plate border

What is 1?

Neural plate

What is 2?

Epidermis

What is 3?

Convergence

What is 1?

Neural fold

What is 2?

Neural groove

What is 3?

Epidermis

What is 1?

Neural tube

What is 2?

Neural crest

What is 3?

Neural tube

the developing brain and spine

neural crest

is a transient, multipotent population of cells that arises during early vertebrate development

fourth germ layer

what is the neural crest often called?

Multipotent

Cell’s ability to develop into multiple—but limited—cell types within a specific lineage or tissue family. Neural crest cells are ________.

Totipotent

can form all cell types, including embryonic + extraembryonic

pluripotent

can form any body cell

multipotent

can form several related cell types

unipotent

can orm one type

• Brain (anterior neural tube)

• spinal cord (posterior neural tube)

CNS

• motor neuron axons

• interneurons

• neuroglia of CNS (except microglia)

  • astrocytes

  • oligodendrocytes

• ependymal cells (lining ventricles)

other structures derived from neural tube

• craniofacial cartilage and bone

• odontoblasts (tooth dentin)

• cranial nerves ganglia (V, VII, IX, X)

• connective tissues of the face

• middle ear bones

cranial neural crest

• melanocytes

• dorsal root ganglia (sensory neurons)

• sympathetic chain ganglia

• adrenal medulla (chromaffin cells)

• schwann cells and peripheral glia

trunk neural crest

• aorticopulmonary septum

• smooth muscle of great arteries

• ouflow tract of the heart

cardiac neural crest

vagal and sacral neural crest

• enteric nervous system (Auerbach’s - smooth muscle layers of the GI wall and Meissner’s plexuses - in the submucosa, just beneath the mucosal layer) - defects →Hirschsprung disease (congenital aganglionic megacolon) occurs when neural crest cells fail to migrate to the distal colon

• olfactory epithelium

  • receptor cells

  • supporting cells

olfactory placode

• lens

  • far vision, near vision

lens placode

• inner ear

  • cochlea

  • vestibule

  • semicircular canals

otic placode

• nodose ganglion - CN 10 - Vagus

• trimeginal ganglion - CN 5 - trigeminal

• geniculate ganglion - CN 7 - facial

cranial nerves

• epithelial cells - epidermis, nails, hair, sweat glands, nasal cavity, oral cavity, ear canal, inferior anus

surface ectoderm

Mesoderm

germ layer present in animal embryos that gives rise to specialized tissue types

1. paraxial mesoderm

2. intermediate mesoderm

3. lateral mesoderm

   1. somatic layer

   2. splanchnic layer

4 types of mesoderm

Paraxial mesoderm

immediately beside the notochord and neural tube

• somites

• somitomeres

Derivative structures of paraxial mesoderm

• sclerotome

• dermatome

• myotome

somites differentiate into:

sclerotome

somite that become vertebrae, ribs, skull base

dermatome

somite that turns into dermis of the back

myotome

somite that turns into skeletal muscles of the body wall and limbs

Somitomeres

Paraxial mesoderm derivative that forms the axial skeleton, true skeletal muscles, and dorsal dermis

somites

Are blocks of mesoderm that are located on either side of the neural tube in the developing vertebrate embryo.

Sclerotome

is derived from a ventromedial part of the somite and is formed by epithelial—mesenchymal transition

Dermomyotome

is derived from the epithelial dorsolateral part of the somite

• spinal meninges

• dermis, subcutaneous tissue

Dermatome

• epiaxial muscles

• hypaxial

myotome

• vertebrae

• intervertebral disc

• ribs

sclerotome

Intermediate mesoderm

Between paraxial mesoderm and lateral plate mesoderm

• kidneys

• ureters

Renal system

• testis/ovaries

• epididymis/vas deferens

• fallopian tube/uterus

gonads

Lateral mesoderm

Type of mesoderm that has 2 layers

• somatic layer

• splanchnic layer

two layers of the lateral mesoderm

Endoderm

• foregut

• midgut

• hindgut

• primitive pharynx

• pharyngeal pouches

• foregut pouches

• cloacal membrane

• pectinate line

pectinate line

endoderm-derived

• 2/3 anal canal

ectoderm-derived

• 1/3 anal canal

cloacal membrane

anterior

• urogenital canal sinus

  • bladder, prostate, urethra (males)

posterior

• anal canal

foregut pouches

first

• respiratory tract

second

• hepatic (liver, gall bladder)

third

• pancreatic (pancreas)

pharyngeal pouches

first

• middle ear

• auditory tube/eustachian tube

second

• tonsils (tubal, pharyngeal, lingual, palatine)

third/fourth

• superior parathyroid gland

• inferior parathyroid gland

• c-cells

• thyroid

• thymus

hindgut

• distal 1/3 of transverse colon

• descending colon

• sigmoid colon

• rectum and anal canal

midgut

• last 2 parts of duodenum

• jujenum

• ileum

• cecum

• ascending colon

• proximal 2/3 of transverse colon

foregut

• pharynx

• esophagus

• stomach

• first 2 parts of duodenum