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August 08, 2006


I'm writing a script for my presentation. Please ignore me.


Archive no: 5
File Name: 39-1.2B.r2s4.10x.Slit2-3A10
Embryonic day: 4


This is a microscope imaging of part of the chick inner ear of an E4 embryo. At this age the ear is still a globular structure called the otocyst. With cell lineage analysis we can precisely determine the development pathway for different areas of presensory cells, but for my exercise i'm learning how to identify the anatomy of the chick inner ear.

*eye contact, eye contact*

Now we are looking at the ventral view of the left otocyst (point on the projector screen) located at the medial-posterior side of the image. This section is double-stained with Slit2 and 3A10, the former expressed in blue color and the latter, brown.

We are actually now looking at the more dorsal section of the otocyst, so what we have here, I deduce from previous papers, are the presensory areas of the anterior cristae (point at ac) and posterior cristae (ditto at pc). To further prove this, the adjacent section to this one (switch to next image) which is stained with Bmp4 shows both areas that are presumed to be ac and pc are expressing Bmp4. In Laura Cole et all paper, "Sensory Organ Generation in the Chick Inner Ear: Contributions of Bmp4, Ser1 and L-fng", there are 2 Bmp4 images of Stage 23/24 embryo... oh my embryo is staged at 21.. which shows morphologically similar areas in the otocyst which are stained. Therefore i dare to suggest that the ac and pc are correctly labeled.

The endolymphatic duct (point at ed) is a non sensory part of the the otocyst which will function as a connector to transfer fluid from endolymphatic sac to the hollow regions in a fully developed ear. But is it possible that the ed is expressing Slit2? I'm not very sure about that. Or maybe that is not the endolymphatic duct. I only deduce it from the Cole paper. The only analysis that i can explain is that... alamak what can i say now... hmm.. okay talk about the neuronal midline.. The neuronal midline has a beautiful expression of Slit2.. This is most famously known from the study of Slits and RObos in Drosophila Melanogaster. In Drosophila, the midline expresses strong signal of Slit2 to repel Commissureless axons after crossing the midline to prevent the axons form recrossing. The image is insufficient to show the same conclusion in the case of chick inner ear, but from the expression of 3A10, which shows neurofilaments stained in brown color, there are abundant of axons crossing the midline, regulated by Slits and Robos.

Hmm.. enough for today la. Tiredness...

Posted by peixin at August 8, 2006 09:16 AM


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