Embryology
Embryogenesis
- Zygote
- Morula
- Blastocyst
- Embryoblast [Inner cell mass]
- Trophoblast [Outer cell mass]
- Cytotrophoblast
- Syncitiotrophoblast
Embryonic Development
| Week | Milestones |
|---|---|
| 1 | Implantation |
| 2 | Bilaminar disc |
| 3 | Trilaminar disc Gastrulation Neurulation |
| 4 | Heart Pharyngeal arches Limb buds |
| 5 | Lens pit Nasal pit |
| 6 | Hand plate Foot plate |
| 7 | Finger rays |
| 8 | Fetal movement |
| 10 | Genitalia |
Extraembryonic Membranes {CAYA}
| Membrane | Derivatives | Remnant | Markers |
|---|---|---|---|
| Chorion | Placenta | - | hCG |
| Amnion | Umbilical chord | - | AFP |
| Yolk sac | Vitelline duct | Meckel's diverticulum | AFP |
| Allantois | Allantoic duct | Urachal diverticulum | AFP |
Ectoderm
Surface Ectoderm
- Anterior pituitary
[Adenohypophysis] - Epidermis
- Lens
- Mammary gland
- Salivary gland
- Sensory organs
- Sweat gland
- Urethra :: penile
- Urogenital fold
Neuroectoderm :: Neural Tube
- CNS neurons
- CNS glial cells
- Astrocytes
- Ependymal cells
- Oligodendrocytes
- Olfactory nerve
- Optic nerve
- Pineal gland
- Posterior pituitary
[Neurohypophysis] - Retina
Neuroectoderm :: Neural Crest
- Adrenal medulla
- Endocardial cushions
- Leptomeninges
- Melanocytes
- Odontoblasts
- PNS ganglia
- Schwann cells
- Spiral membrane
Mesoderm
- Adrenal cortex
- Blood
- Connective tissue
- Cardiovascular
- Dermis
- Genital ducts
- Mullerian duct
[Paramesonephric duct] - Wolffian duct
[Mesonephric duct]
- Mullerian duct
- Gonads
- Kidney
- Lymphatics
- Muscle
- Notochord
- Serosa
- Pleura
- Pericardium
- Peritoneum
- Spleen
Endoderm
- Eustachian tube
- Gastrointestinal tract
- Liver
- Lung
- Pancreas
- Parathyroid
- Thymus
- Thyroid
- Follicular cell
- Parafollicular [C] cell
- Urethra :: prostatic & membranous
- Urinary bladder
- Urogenital sinus
Pharyngeal Apparatus {CAP}
| Component | Origin |
|---|---|
| Cleft | Ectoderm |
| Arch | Mesoderm |
| Pouch | Endoderm |
Pharyngeal Cleft
| Derivatives | |
|---|---|
| 1 | External auditory meatus |
| 2 3 4 | Cervical sinus Pharyngeal cleft cyst |
Pharyngeal Arch
| Bones & Cartilages | Muscles | Nerves | |
|---|---|---|---|
| 1 | Zygomatic bone Maxillary bone Mandible Meckel cartilage Malleus Incus | Masticatory muscles Mylohyoid Digastric muscle :: anterior belly Tensor tympani Tensor veli palatini | CN V3 |
| 2 | Stapes Styloid process Hyoid :: lesser horn | Stapedius Facial muscles Digastric muscle :: posterior belly Stylohyoid | CN VII |
| 3 | Hyoid :: greater horn | Stylopharyngeus | CN IX |
| 4 | Laryngeal cartilages | Palatal muscles - Tensor veli palatini Pharyngeal muscles - Stylopharyngeus Levator veli palatini Cricothyroid | CN X :: pharyngeal branch CN X :: superior laryngeal nerve |
| 6 | Laryngeal cartilages | Laryngeal muscles - Cricothyroid | CN X :: recurrent laryngeal nerve |
Pharyngeal Pouch
| Derivatives | |
|---|---|
| 1 | Middle ear Eustachian tube |
| 2 | Tonsil |
| 3 | Thymus Inferior parathyroids |
| 4 | Superior parathyroids Parafollicular [C] cells |