Embryonic Phases
Phase from conception to 2 weeks including zygote division and implantation.
What is the pre-embryonic phase?
Layer that forms skin and nervous system.
What is the ectoderm?
Number of somite pairs formed during segmentation.
What is 44 pairs?
The neural tube becomes this system.
What is the central nervous system?
The maternal tissue into which the blastocyst implants.
What is the endometrium?
Phase during which major organs and structures begin forming.
What is the embryonic phase?
Layer that forms muscle, bone, and blood.
What is the mesoderm?
Somite division that forms the dermis of the skin.
What is the dermotome?
Forebrain derived from this embryonic brain vesicle.
What is the prosencephalon?
Protective coating around the egg that prevents wrong-site implantation.
What is the zona pellucida?
Phase from end of week 8 to birth, focused on tissue maturation.
What is the fetal phase?
Layer that forms the lining of gut and lungs.
What is the endoderm?
Somite division that forms skeletal muscles.
What is the myotome?
Cells from neural tube that form most of the peripheral nervous system.
What are neural crest cells?
Fingerlike projections from trophoblast that form placenta.
What are chorionic villi?
Errors in this phase cause major morphological abnormalities.
What is the embryonic phase?
Layer originating from epiblast cells that displace the hypoblast.
What is the endoderm?
$600: Somite division that forms vertebral column bones and ligaments.
What is the sclerotome?
This structure coordinates the formation of the primitive streak and helps establish the body’s early axes during gastrulation.
What is the primitive node?
Blastocyst inner cell mass develops into this two-layered structure.
What is the embryonic disc?
Phase where the embryo is not susceptible to teratogens due to lack of blood supply.
What is the pre-embryonic phase?
Germ layer that gives rise to somites contributing to vertebrae and muscles.
(hint: not one of the OG germ layers, rather a subcategory)
What is the paraxial mesoderm?
Mesoderm division forming the urinary system.
What is the intermediate plate?
This structure degenerates but persists as the nucleus pulposus in intervertebral discs.
What is the notochord?
This term describes the solid ball of 16-32 cells formed by rapid cell division after fertilization, just before it develops into a blastocyst.
What is the morula?