Layers of Frog

Ectoderm (Outer Layer)

• Epidermis - placodes, glands, scales, hair, nail

• Neural Tube - CNS, eyes, motor nerve

• Neural Crest - PNS

• Extra-embryonic ectoderm - Amnion

Mesoderm (Middle Layer)

• Chordamesoderm - notochord

• Head mesenchyme - facial connective tissue

• Paraxial mesoderm

  • Somites - dermis, skeleton, limb muscles

• Intermediate mesoderm

  • Urogenital system - kidneys

• Lateral Plate Mesoderm

  • Somatic mesoderm - parietal pleura, pericardium, parietal peritoneum

  • Splanchnic mesoderm - heart, blood, blood vessels, visceral pleura, visceral peritoneum, mesenteries, visceral connective tissue, gonad stroma, yolk sac mesoderm

• Somatic mesoderm - parietal pleura, pericardium, parietal peritoneum

• Splanchnic mesoderm - heart, blood, blood vessels, visceral pleura, visceral peritoneum, mesenteries, visceral connective tissue, gonad stroma, yolk sac mesoderm

Endoderm

• Primitive gut - digestive system, respiratory system

• Extra-embryonic endoderm - endoderm of yolk sac

• Allantois

Germ Cells - oocytes, sperm

• Heart, blood, blood vessels, visceral pleura, visceral peritoneum, mesenteries, visceral connective tissue, gonad stroma, yolk sac mesoderm - under splanchnic mesoderm

• Parietal pleura, pericardium, parietal peritoneum - under somatic mesoderm

Label From Head Ectodermal

• Prosencephalon - upper area of the embryo

• Telencephalon and Diencephalon - divided prosencephalon

• Nasal Placodes (inner ectodermal) - ventral to prosencephalon

• Olfactory receptors and axons of olfactory - located with nasal placodes

• Pineal gland - located dorsal to prosencephalon

• Optic cup - located posterior to prosencephalon

• Sensory retina - thick part of optic cup

• Pigmented Retina - thin part of optic cup

• Lens placode - adjacent to optic cup

• Mesencephalon - second layer posterior to prosencephalon

• infundibulum - ventral to mesencephalon; source of posterior pituitary gland

• posterior pituitary gland - located at the infundibulum

• Auditory vesicle (inner ear) - posterior to the pituitary gland

• Spinal cord - posterior to inner ear

• Neural crest - dorsal to spinal cord

• Rhombencephalon - dorsal to the mesencephalon

• Metencephalon and Myelencephalon - divided parts of rhombencephalon

Endodermal

• Foregut (endoderm) - cranial to prosencephalon

• Mouth opening (stomodeal ectoderm) - below foregut

• Pharynx - 3rd layer (endodermal) posterior to prosencephalon

• Liver rudiment - 3rd layer (endodermal) ventral to prosencephalon

• Duodenum - ventral to the liver rudiment

• Midgut - below duodenum

• Hindgut - ventral to midgut

• Cloacal membrane to anus - more posterior to hindgut

Mesodermal

• Notochord - posterior to infundibulum

• Subnotochordal rod (hypochord) - located in caudal regions of notochord

• Pronephric duct - round vesicles on each side farthest from the spinal cord

• Pronephric tubules - it is above pronephric ducts

• Pronephric kidneys - composes of pronephric duct and tubules

• Lateral plate mesoderm - ventral to pronephric kidney

• Somatic and Splanchnic mesoderm- two divided parts of lateral plate mesoderm

• Somatic mesoderm - outer layer of lateral plate mesoderm

• Splanchnic mesoderm - inner layer of lateral plate mesoderm

• Coelom - small spaces between the somatic and splanchnic mesoderm

• Bulbus cordis - located posterior to the foregut; it is beneath the pharynx

• Heart - near bulbus cordis

• Endocardium and Myocardium - two layers of the heart

• Endocardium (splanchnic mesoderm) - inner layer

• Myocardium (splanchnic mesoderm) - outer and thick layer

• Parietal pericardium (somatic mesoderm) - thin layer of cells enclosing the heart

• Pericardial cavity - space between the eat and the parietal pericardium

• Dorsal mesocardium - dorsal bridge of splanchnic mesoderm

• First aortic arches - lie ventrolateral to the pharynx

• Dorsal aorta - extend caudad and fade out at about the level of the midgut