Ectoderm
- Surface ectoderm
- sensory organs
- ear
- olfactory epithelium
- epithelial linings
- oral cavity
- lower anal canal
- external auditory meatus
- epidermis, hair, and nails
- mammary, sweat, and salivary glands
- sensory organs
- Neuroectoderm – CNS and brain
- brain – all neurons within brain and spinal cord/CNS
- neurohypophysis
- oligodendrocytes
- astrocytes
- ependymal cells
- pineal gland
- retina
- brain – all neurons within brain and spinal cord/CNS
- Neural Crest – PNS and nearby non-neural structures
- ANS
- ganglia (dorsal root, cranial, and autonomic)
- cranial nerves
- celiac ganglion
- chromaffin cells of adrenal medulla
- enterochromaffin cells
- Schwann cells
- pia and arachnoid
- bones of the skull
- odontoblasts
- aorticopulmonary septum
Endoderm
- Epithelium lining of
- respiratory: trachea, bronchi, and lungs
- urinary: urinary bladder, female urethra, and majority of male urethra
- GI tract
- biliary system
- lower 2/3 of vagina
- middle ear cavity and auditory tube
- Liver
- Parathyroid
- Thyroid follicular cells
- Thymus
- Pancreas
- Parafollicular (C) cells of thyroid
| Mesoderm |
- Muscle (smooth, cardiac, and skeletal)
- Dermis and subcutaneous layers of skin
- Bone, cartilage, and connective tissue
- Dura mater
- Serous linings of body cavities
- peritoneum
- Spleen
- Cardiovascular structures
- Lymphatics
- Laryngeal cartilage
- Blood: RBCs, WBCs, Kupffer cells, and microglia
- Urogenital structures
- male: testes, epididymis, ductus deferens, seminal vesicle, and ejaculatory duct
- female: ovaries, uterus, uterine tubes, and upper 1/3 of vagina
- Kidneys
- Adrenal cortex
Defects
- Types of errors
- malformation vs. deformation
- malformation is intrinsic embryological disruption during the embryonic period
- deformation is extrinsic disruption, occurs after embryonic period
- agenesis vs. hypoplasia vs. aplasia
- agenesis = organ is absent because of absent primordial tissue
- e.g., renal agenesis – failure of one or both kidneys to develop
- hypoplasia = organ develops incompletely with remnant primordial tissue
- e.g., microorchidism in Klinefelter syndrome
- aplasia = organ absent but primordial tissue present
- e.g., thymic aplasia in DiGeorge syndrome
- agenesis = organ is absent because of absent primordial tissue
- malformation vs. deformation
- Craniopharyngioma
- Mesodermal defects VACTERL
- Vertebral defects: usually small hypoplastic vertebrae or hemivertebrae, only half of the bone is formed
- Cardiac defects: ventricular septal defect, atrial septal defect, and Tetralogy of Fallot
- Tracheo-Esophageal fistula
- Renal defects: incomplete formation of one or both kidneys
Limb defects: absent or displaced thumbs, polydactyly, and syndactyly