Lecture 2 (FIRST MIDTERM) Flashcards
3 germ layers from out to in:
Ectoderm
Mesoderm
Endoderm
6 main chordate features:
Notochord Pharyngeal slits Endostyle or thyroid gland Dorsal Hollow Nerve Tube Postanal tail Segmented body musculature
The concept of “a tube in a tube” (like us) is called:
gastrulation
Where the ectoderm thickens, there is a specific germ layer called…
neural plate ectoderm
What is neurulation?
Ectoderm “rolls up” and leaves a hollow core (dorsal hollow nerve tube)
What are pharyngeal slits?
Piercings or almost piercings (which are pharyngeal pouches)
Probably functioned in feeding or respiration in early chordates
Endostyle:
Thyroid gland:
Endostyle: a ciliated groove in the floor of the mouth - present in early chordates
Thyroid gland: present in more advanced chordates
The central nervous system in chordates develops embryologically from…
ectoderm
What is the name of the canal going down your spinal cord?
neurocoel
Post-anal tail:
A tail extending beyond the anus
Primarily for swimming in lower chordates
Segmented body musculature:
Blocks of muscle that are arranged along the length of the body
The notochord is embryologically derived from…
mesoderm
The notochord is dorsal to what?
The coelom (body cavity)
The notochord is ventral to what?
The central nervous system
Neural crest ectoderm turns into..
Peripheral nervous system, ganglia of nervous system (cranial, spinal, autonomic), dentine of teeth, head skeleton, pigment cells, covering of the brain (meninges)
Most superficial layer in an embryo (specific germ layer):
epidermal ectoderm
Specific germ layer of the dorsal hollow nerve tube:
neural ectoderm
Three divisions of the mesoderm:
Epimere
Mesomere
Hypomere
Epimere forms what structures?
Somites
3 types of Epimere and description:
Dermatome: dermis
Myotome: axial, limb, and body wall musculature
Sclerotome: vertebral column and ribs
Specific germ layer of the notochord:
chordamesoderm
Specific germ layer of somites:
paraxial mesoderm
Intermediate mesoderm falls under this category:
mesomere
The intermediate mesoderm forms…
urogenital system
Dorsal hollow nerve tube forms…
central nervous system
Specific germ layer of splanchnic lateral plate mesoderm…
lateral plate mesoderm
Specific germ layer of somatic lateral plate mesoderm…
lateral plate mesoderm
The Splanchnic lateral plate mesoderm forms…
heart, blood vessels, smooth muscle of digestive system
The Somatic lateral plate mesoderm forms…
limb skeletons
Hypomere consists of…
Somatic lateral plate mesoderm and Splanchnic lateral plate mesoderm
What lines the digestive tube?
endoderm
Endoderm lining of the digestive tube:
- Abdominal foregut: stomach, liver, pancreas, beginning of small intestine
- Abdominal midgut: most of small intestine, beginning of large intestine
- Abdominal hindgut: terminal intestines, urinary bladder
Segmentation is most obvious in what derivatives?
Mesoderm derivatives
Somites (dermatome, myotome, schlerotome)
Transsegmental structures:
Dorsal hollow nerve tube Notochord Dorsal aorta Gut Coelom Lateral mesoderm Surface ectoderm
What does transsegmental mean?
Continuous (longitudinal)
Segmented structures:
Somites
Intermediate mesoderm
Segmental arteries
Segmental nerves
Inner lining of the digestive tube is _________ and the outer lining is __________
Inner lining of the digestive tube is endoderm and the outer lining is mesoderm
Parietal serosa lines…
And is associated with…
the inside of somatic lateral plate mesoderm
and is associated with the body wall
Visceral serosa lines…
the gut wall “outside”
Parietal serosa and visceral serosa are types of…
peritoneum (inside abdominal cavity)
The “space” in between the body wall “tube” and the gut wall “tube” is called…
coelom
The connection between body wall and plate mesoderm is called…
Somatopleure
The connection between mesoderm and endoderm is called…
Splanchnopleure
The “openings” that act as bridges for blood vessels to the gut tube are called…
Dorsal mesentery and ventral mesentery
Which mesentery is closer to the aorta/notochord/DHNT?
Dorsal mesentery
Explain neurulation.
Single layer of epidermal ectoderm with thickening in the middle (neural plate - neural ectoderm)
Plate starts to fold and neural folds move toward each other and create a neural groove
(just beneath the neural folds is neural crest tissue)
Neural folds come together and create a tube, which separates from epidermal ectoderm
Becomes Dorsal Hollow Nerve Tube (still neural ectoderm)
