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