10mm Frog Tadpole

The 10 mm frog embryo Bio 132 – Animal Developmental Biology Created 1st sem, AY 2012-2013 For the 1st practical exam

Early Stages of Development

Cleavage  

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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  Blastocoel  Blastoderm  Macromeres  Micromeres 

Early gastrula  Dent ◦ Invagination to form archenteron 

Animal hemisphere ◦ Above blastocoel ◦ Micromeres ◦ Small, many, nuclei may not be visible ◦ Numerous and rapid cell division

Early gastrula

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Vegetal hemisphere ◦ ◦ ◦ ◦

Below blastocoel Yolk-laden Large but few Yolk impedes cell division ◦ Granular due to yolk platelets 

Blastocoel ◦ 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

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Yolk plug Dorsal and ventral lip of blastopore Ectoderm (derivatives?) Endoderm (derivatives?) Mesoderm (derivatives?) Blastocoel Archenteron chordamesoderm Why did the blastopore close? The infidibulum

Closed blastopore stage Yolk plug  Dorsal and ventral lip of blastopore  Blastocoel  Archenteron  Why did the blastopore close? The infidibulum 

n. plate

Neural fold

n. tube

Notochord  Neural crest  Somites  Epimere/mesome re/hypomere  Somatic/splanchn ic mesoderm  Somatopleure/spl anchnopleure 

Ectodermal derivatives

Ectodermal derivatives 

Telencephalon

◦ Origin: prosencephalon ◦ Fate: cerebrum ◦ Function: storage of memory, control of consciousness, voluntary action ◦ Cavity: Lateral ventricle ◦ Lamina terminalis ◦ Olfactory nerve

Ectodermal derivatives 

Diencephalon ◦ ◦ ◦ ◦ ◦ ◦ ◦

Optic recess Epiphysis Optic chiasma Optic nerve hypophysis Infundibulum Cavity: third ventricle  Fate: epithalamus, hypothalamus, thalamus

Ectodermal 

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

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Metencephalon ◦ Trochlear nerve

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Myelencephalon ◦ 4th ventricle (cavities of meten and myelen)

Ectodermal 

Cranial Nerve Ganglia ◦ ◦ ◦ ◦

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Semilunar Acoustico-fascialis Glossopharyngeal Vagus

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

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Sympathetic ganglia

Ectodermal 

Eye ◦ ◦ ◦ ◦ ◦

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Optic cup Optic lens Retina Pigmented epithelium Sensory retina (rods and cones) Bipolar neurons Ganglion cells Choroid coat Sclerotic coat

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Ear ◦ Otocyst ◦ Utriculus  semicircular canals ◦ Sacculus  cochlea  organ of Corti ◦ Endolymphatic duct

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Olfactory

Ectodermal 

Eye ◦ ◦ ◦ ◦ ◦

◦ ◦ ◦ ◦

Optic cup Optic lens Retina Pigmented epithelium Sensory retina (rods and cones) Bipolar neurons Ganglion cells Choroid coat Sclerotic coat

Ectodermal 

Chondrocranium ◦ ◦ ◦ ◦ ◦

Labial cartilage Trabecular horns Ethmoid plate Palatoquadrate Basicranial fontanelle ◦ Trabeculae ◦ Basilar plate ◦ Parachordals

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Splanchnocraniu m ◦ Mental and Meckelian cartilages ◦ Ceratohyals ◦ Copula (basibranchial) ◦ Hypobranchials ◦ Ceratobranchials

Ectodermal 

Splanchnocraniu m ◦ Mental and Meckelian cartilages ◦ Ceratohyals ◦ Copula (basibranchial) ◦ Hypobranchials ◦ Ceratobranchials

Endodermal 

Branchial region ◦ Pharyngeal pouches ◦ Pharyngeal furrows/grooves ◦ gills and operculum ◦ Thyroid (smileyface)

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Respiratory system ◦ Pharynx ◦ Trachea ◦ Lung buds

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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

Mesodermal 

Epimere ◦ Dermatome ◦ Myotome ◦ Sclerotome

Mesomere  Hypomere 

◦ Somatic mesoderm ◦ Splanchnic mesoderm

Mesodermal 

Urogenital ◦ Mesonephros ◦ Mesonephric tubules and duct ◦ Glomi, nephrostome beside it ◦ Gonadal ridge (also include PCGs)

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Circulatory ◦ Heart      

Atrium Ventricle Sinus venosus Conus arteriosus Ventral aorta Common cardinal veins

Mesodermal 

Urogenital ◦ Mesonephros ◦ Mesonephric tubules ◦ Mesonephric duct ◦ Glomi, nephrostome beside it ◦ Gonadal ridge (also include PCGs)

Mesodermal 

Circulatory ◦ 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

Mesodermal 

Mesenteric artery

Mesodermal 

Subcardinal veins

Mesodermal Dorsal aorta  Postcardinal vein 