- At 3rd week of gestation
- Formation of a three-layered structure
- Exoderm
- Mesoderm
- Endoderm
- Disruption
- Causes split cord anomalies, neurenteric, dermoid and epidermoid cysts, and anterior meningoceles
Stages of gastrulation
Stage | Days | Week |
Morula | 2-3 | 1st |
Bilaminar disc | 4-5 | 1st |
Implantation | 6 | 1st |
Amniotic and yolk sacs formed | 8-12 | 2nd |
Trilaminar disc with primitive streak | 14-17 | 3rd |
Neural plate and groove | 18 | 3rd |
Appearance of three primary brain vesicles | 20 | 3rd |
Anterior neuropore closure | 24-26 | 4th |
Posterior neuropore closure (formation of neural tube) | 26-28 | 4th |
Anterior and posterior roots | 31 | 4th-5th |
Five cerebral vesicles and developing flexures | 35 | 5th |
Primordium of cerebellum | 42 | 6th |
Corpus callosum | - | 10th |
Cerebellar cortex and Purkinje cells | - | 12th |
Dentate nucleus | - | 15th |
Primary cerebral fissure | - | 20th |
Image
Blastopore = primitive pit = neuroenteric canal
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