The 10 mm frog embryoBio 132 – Animal Developmental BiologyCreated 1st sem, AY 2012-2013For the 1st practical exam

Early Stages of Development

Cleavage

Smaller cells called the blastomeres

Morula = ball of cells at 128 cell stage

Animal vs. vegetal pole

Mass still enclosed within the zona pellucida, to prevent early implantation

Blastula Stage

No growth taking place

Controlled by maternal molecules until midblastula

BlastocoelBlastodermMacromeresMicromeres

Early gastrulaDent◦Invagination to form archenteron

Animal hemisphere◦Above blastocoel◦Micromeres ◦Small, many, nuclei may not be visible

◦Numerous and rapid cell division

Early gastrulaVegetal

hemisphere◦Below blastocoel◦Yolk-laden◦Large but few◦Yolk impedes cell

division◦Granular due to

yolk plateletsBlastocoel

◦Purpose: prevents differentiation of top region of animal hemisphere from becoming mesoderm

Middle g

No archenteron

Epiboly Dorsal and

ventral lip of blastopore

Late gastrula Yolk plugDorsal and ventral

lip of blastoporeEctoderm

(derivatives?)Endoderm

(derivatives?)Mesoderm

(derivatives?)BlastocoelArchenteronchordamesoderm Why did the

blastopore close? The infidibulum

Closed blastopore stage

Yolk plugDorsal and

ventral lip of blastopore

BlastocoelArchenteron Why did the

blastopore close? The infidibulum

n. plate

Neural fold

n. tube NotochordNeural crestSomitesEpimere/

mesomere/hypomere

Somatic/splanchnic mesoderm

Somatopleure/splanchnopleure

Ectodermal derivatives

Ectodermal derivativesTelencephalon

◦Origin: prosencephalon

◦Fate: cerebrum◦Function: storage

of memory, control of consciousness, voluntary action

◦Cavity: Lateral ventricle

◦Lamina terminalis◦Olfactory nerve

Ectodermal derivativesDiencephalon

◦Optic recess◦Epiphysis◦Optic chiasma◦Optic nerve◦hypophysis◦ Infundibulum◦Cavity: third

ventricle Fate: epithalamus,

hypothalamus, thalamus

EctodermalMesencephalon

◦Cavity: Aqueduct of Sylvius◦Optic lobes◦Oculomotor nerves

Metencephalon◦Trochlear nerve

Myelencephalon◦4th ventricle (cavities of meten and

myelen)

EctodermalCranial Nerve Ganglia

◦Semilunar◦Acoustico-fascialis◦Glossopharyngeal ◦Vagus

Spinal cord◦Central canal◦Ependyma◦Mantle and marginal layers

Sympathetic ganglia

EctodermalEye

◦Optic cup◦Optic lens◦Retina◦Pigmented

epithelium◦Sensory retina

(rods and cones)◦Bipolar neurons◦Ganglion cells◦Choroid coat

◦Sclerotic coatEar

◦Otocyst◦Utriculus

semicircular canals

◦Sacculus cochlea organ of Corti

◦Endolymphatic duct

Olfactory

EctodermalEye

◦Optic cup◦Optic lens◦Retina◦Pigmented

epithelium◦Sensory retina

(rods and cones)◦Bipolar neurons◦Ganglion cells◦Choroid coat◦Sclerotic coat

EctodermalChondrocranium

◦Labial cartilage◦Trabecular horns◦Ethmoid plate◦Palatoquadrate◦Basicranial

fontanelle◦Trabeculae◦Basilar plate◦Parachordals

Splanchnocranium◦Mental and

Meckelian cartilages

◦Ceratohyals◦Copula

(basibranchial)◦Hypobranchials◦Ceratobranchials

EctodermalSplanchnocraniu

m◦Mental and

Meckelian cartilages

◦Ceratohyals◦Copula

(basibranchial)◦Hypobranchials◦Ceratobranchials

EndodermalBranchial region

◦ Pharyngeal pouches◦ Pharyngeal

furrows/grooves◦ gills and operculum◦ Thyroid (smileyface)

Respiratory system◦ Pharynx◦ Trachea◦ Lung buds

Digestive system◦ Buccal cavity◦ Mouth (stomodeum)

◦ Pharynx◦ Esophagus◦ Stomach (with rugae)◦ Liver◦ Pancreas◦ Pancreatic duct◦ Gall bladder◦ Hepatic duct◦ Cystic duct◦ Common bile duct◦ Intestines◦ Cloaca◦ Anus

MesodermalEpimere

◦Dermatome◦Myotome◦Sclerotome

MesomereHypomere

◦Somatic mesoderm◦Splanchnic mesoderm

MesodermalUrogenital

◦Mesonephros◦Mesonephric

tubules and duct◦Glomi,

nephrostome beside it

◦Gonadal ridge (also include PCGs)

Circulatory◦Heart

Atrium Ventricle Sinus venosus Conus arteriosus Ventral aorta Common cardinal

veins

MesodermalUrogenital

◦Mesonephros◦Mesonephric

tubules◦Mesonephric duct◦Glomi,

nephrostome beside it

◦Gonadal ridge (also include PCGs)

MesodermalCirculatory

◦Veins Anterior cardinal

vein lateral to otocyst

Common cardinal Small inferior

jugular Posterior cardinals Subcardinals Postcava Hepatic

Hepatic portal

◦Arteries Efferent branchial Internal carotid 2nd-4th branchial Dorsal aorta

branches Intersegmental Mesenteric caudal

Afferent branchial Lingual/external

carotid

MesodermalMesenteric

artery

MesodermalSubcardinal

veins

MesodermalDorsal aortaPostcardinal

vein