2nd, 3rd and 4th weeks of development:
- Week 2 : Bilaminar germ disc
- Week 3 : Trilaminar germ disc
- Week 4 : Appearance of 4 limbs
Major Neural Crest Derivatives:
“GAMES”
- Glial cells of peripheral ganglia
- Arachnoid and Pia Sheath
- Melanocytes
- Enteric ganglia
- Schwann cells
Neuroectoderm derivatives
- Neurons
- Neuroglia
- Neurohypophysis
- piNeurol (pineal) gland
Foregut derivatives
“Little Embryo People Do Like Swallowing, Producing Gas”
- Lungs
- Esophagus
- Pancreas
- Duodenum (proximal)
- Liver
- Stomach
- Pancreas
- Gall bladder
Occurrence of Teratogenesis
TEratogenesis
Between Third and Eighth weeks of gestation.
Derivatives of Mesoderm:
“MESODERM”
- Mesothelium (peritoneal, pleural, pericardial)/ Muscle (striated, smooth, cardiac)
- Embryologic Spleen/ Soft tissue/ Serous linings/ Sarcoma/ Somite
- Osseous tissue/ Outer layer of suprarenal gland (cortex)/ Ovaries
- Dura/ Ducts of genitalia
- Endothelium
- Renal Microglia
- Mesenchyme/ Male gonad
Branchial apparatus:
“CAP covers from outside to inside.”
- C for Clefts : derived from ectoderm
- A for Arches : derived from mesoderm and neural crest
- P for Pouches : derived from endoderm
Chromosomal disorders:
- Edward syndrome : election age-ch-18
- Down syndrome : drinking age-ch-21
- Patau syndrome : puberty age-ch-13
Fetal Hemopoesis (for Physiology):
“Young Liver Synthesizes Blood”
- Y : Yolk Sac (from 3 weeks)
- L : Liver (from 3 months)
- S : Spleen (from 3 months)
- B : Bone marrow (5 month onwards)
After birth hemopoesis occurs only in bone marrow except in case of emergency when bone marrow falls.
Fetal alcohol syndrome (FAS):
“FAS”
- F : Facial hypoplasia and Forebrain malformation
- A : Attention defecit disorder and Altered joints
- S : Short stature, Septal defects and Small I.Q
Neural Crest Derivatives
“4 Gang MEN wore CAP”
A. 4 Gang (4 ganglias)
- Dorsal root ganglia of spinal nerves
- Ganglia of V, VII, IX and X cranial nerves
- Sympathetic & parasympathetic ganglia (autonomic ganglia)
- Ganglion cell layer of retina
B. MEN
- Melanoblast of the skin
- Enamel of teeth
- Neurilemma (Schwann cells)
C. CAP
- Chromaffin cells and Cranio-facial skeleton
- Arachnoid and Pia Maters
First Branchial Arch:
“IMPACTS”
Most of the aspects associated with the first arch begin with the letter ‘M’ and the rest with I, P, A, C, T or S.
- Name : Mandibular arch.
- Muscles :
- Muscles of Mastication (Masseter, Temporalis, Medial & Lateral Pterygoids)
- Mylohyoid
- Anterior belly of Digastric
- Tensor tympani and Tensor palatini
- Cartilage : Meckel’s cartilage
- Malleus & Incus, Sphenomandibular ligament & Anterior ligament of Malleus
- Innervation : Mandibular nerve, Chorda tympani
Cartilage derivatives of 2nd branchial arch:
5 “S”
- Stapes
- Styloid process
- Stylohyoid ligament
- Smaller (lesser) cornu of hyoid
- Superior part of body of hyoid
Derivatives of Pharyngeal Pouches:
“1A, 2P, 3 TIP, 4 SPUB”
- 1A (1st Pharyngeal Pouch – Auditory)
- Epithelial lining of Auditory tube , middle ear cavity and mastoid antrum
- 2P (2nd Pharyngeal Pouch – Palatine)
- Epithelial lining of crypts of Palatine tonsil
- 3 TIP (3rd Pharyngeal Pouch – Thymus and Inferior Parathyroid gland)
- Thymus and Inferior Parathyroid gland
- 4 SPUB (4th Pharyngeal Pouch – Superior Parathyroid gland and Ultimobranchial Body)
- Superior Parathyroid gland and Ultimobranchial Body
Nerves:
“March 5, 7910”
- 1 : V3 (March for 3 and 5 for V)
- 2 : VII (7)
- 3 : IX (9)
- 4 & 6 : X (10)
