l2 Flashcards
where is Shh expressed ?
in VENTRAL midline cells of axial mesoderm (notochord) and floorplate
- seen by insitu hybridisation
- Shh expression in notochord induces Shh expression in floorplate, Shh expressing FP can induce more Shh expressing FP cells.
what underlies the developing ventral brain?
prechordal mesoderm (fan like structure) (induces hypothalamus)
why is difficult to pinpoint what PM underlies?
because the PM is a moving cell population
how can you see the early descendents of the PM?
fate map
- inject Dil into cells immediatly above the PM
- cling film and incubate tissue
- develop embryo into an egg untill distinct forebrain regions identified
-cells that were above the PM give rise to the HYPTHALAMUS
what do cells directly above the PM give rise to?
hypothalamus
what would be the negative control in the experiment which shows PM gives rise to hypothlamus?
fatemap other areas to show that this area doesn’t form hypothalamus
- specific to are above the PM to form hypothalamus
- confirms finding
what is the function of the hypthalamus?
maintains core homeostasis and integrates autonomic response and endocrine function with behaviour
what do all hypothalamic progenitors express when first produced?
Fgf
what happens when the PM is ablated?
- fail to induce markers of the hypthalamus
- no BMP7 (marker) expression in forming diencephalon
- Shh is required for BMP7 expression
what happens when neural tissue is cultured alone with PM?
- PM is sufficient to induce hypothalamic progenitor cells
- PM is shown to induce hypothalamus
how is the PM fist identified?
identified on the basis of known markers
- Gsc, Shh, Nodal and BMP7
what is the difference in BMP expression between the sc and forebrain
in SC BMPs are expressed dorsally but in forebrain BMPs are expressed ventrally
what happens when Shh is deleted?
there is no hypothalamic development
-Shh is required to maintain the PM
what does the Shh from the PM first induce?
-first induces Shh+ pre-hypothalamic cells and early ventralisation
What does Shh need in order to induce Shh in other cells?
needs nodal
not needed in SC
