Early Development & Organogenic Period Flashcards
The formation of a trilaminar embryo occurs in what stage of embryonic development?
Gastrulation
During fertilization, the spermatozoa enters the ovum by puncturing what noncellular structure?
Zone pellucida
What is a morula?
16-cell mass
What fluid filled cavity is formed from the permeation of fluid into a morula?
Blastocoele
Which structure gives rise to the placenta?
Trophoblast
What is the Heusers membrane?
Hypoblast cells lining the blastocyst cavity
What will give rise to the future site of the umbilical cord in the embryoblast?
Connecting stalk
What does the epiblast subdivide into?
Ectoderm, endoderm and mesoderm, set of 3 different germ cells that differentiate into specific and distinct tissues
The bilaminar embryo becomes polarized by which structure that will also give rise to the mouth?
Prechordal plate
What is the group of specialized cells that migrate through the primitive node towards the prechordal plate?
Notochordal process
The mesoderm migrates cranial and lateral to the prechordal plate to become?
The cardiogenic mesoderm
What is the most common neonatal tumor that arises from the primitive streak?
Teratoma
The right-left patterning of the body is influenced by what signaling molecule?
Nodal
What can primary cilliary dyskinesia result in?
Situs inversus
What is caudal dysgenesis also known as?
Sacral agenesis syndrome
There are simultaneous processes occurring regarding the ectoderm, mesoderm and endoderm, what are they?
- Ectoderm is folding to create the neural tube, central nervous system and epidermis of the skin
- Mesoderm (paraxial) into somites which are part of the musculoskeletal system. Intermediate mesoderm into urogenital system
Lateral plate mesoderm into supporting tissues of gastrointestinal tract, body wall and limbs - Endoderm into continuous tube called gut tube which will become lining of gastrointestinal, urogenital and respiratory systems
The CNS is derived from which embryonic layer?
Ectoderm
The urogenital system is derived from which embryonic layer?
Intermediate mesoderm
The neural ganglia arises from which embryonic structure?
Neural crest
The failure of neuropore closure results in what congenital defect that is not compatible with life?
Anencephaly
The failure of the neural folds to close on time prevents the vertebrae from forming properly. What is the congenital defect that may result from this delay, which is usually mild and typically has no associated CNS deficits?
Spina bifida occulta
What are the 4 types of spina bifida?
- Spina bifida occulta
- Spina bifida meningocele
- Spina bifida meningomyelocele
- Myeloschisis/ rachescis (closed neural tube defects)
What are the divisions of somites?
4 occipital 8 cervical 12 thoracic 5 lumbar 5 sacral and coccygeal
Somites come from the paraxial mesoderm, what three regions do they split into that come up with 3 distinctive sets of structures?
- Dermatome: dermis
- Myotome: muscles of back, trunk and limbs
- Sclerotome: vertebrae, intervertebral discs, meninges and ribs
