Bird neural canals are weird, part 3: the glycogen body
January 17, 2019
I planned to post this last spring but I never got around to it. I think I have a mental block about discussing the glycogen body. Partly because I’ve been burned by it before, partly because no-one knows what it does and that’s unsatsifying, partly because I didn’t want to plow through all the new literature on it (despite which, the function remains unknown).
Then I decided, screw it, I’ll let the slides speak for themselves, and the actual text of the post can just be navel-gazing and whingeing. Which you are “enjoying” right now.
So, there’s the glycogen body. It balloons out between the dorsal halves of the spinal cord, it’s made of glial cells (neuron support cells) that are packed with glycogen, and nobody knows why it’s there. On the graph of easy-to-find and frustrating-to-study it is really pushing the envelope.
Update: the role of the glycogen body in the ‘second brain’ myth is covered in the next post.
Previous entries in the “Bird neural canals are weird” series:
- Bird neural canals are weird, part 1: intro and supramedullary diverticula
- Bird neural canals are weird, part 2: the lumbosacral expansion
Here are some stubbornly-not-updated references for the images I used in the slides:
- Huber, J.F. 1936. Nerve roots and nuclear groups in the spinal cord of the pigeon. Journal of Comparative Neurology 65(1): 43-91.
- Streeter, G.L. 1904. The structure of the spinal cord of the ostrich. American Journal of Anatomy 3(1):1-27.
- Watterson, R.L. 1949. Development of the glycogen body of the chick spinal cord. I. Normal morphogenesis, vasculogenesis and anatomical relationships. Journal of Morphology 85(2): 337-389.
Sauropod Vertebra Picture of the Week 
January 18, 2019 at 12:36 pm
Could this be related to the infamous “second brain” of stegosaurus?
January 18, 2019 at 5:12 pm
[…] Marco brought up in the comments on the previous post, glycogen bodies are probably to blame for the idea that some dinosaurs had a second brain to run […]
January 18, 2019 at 5:12 pm
Yep – you anticipated my next post beautifully. Here it is.
January 18, 2019 at 9:44 pm
Sorry for the spoiler, thank you for reply and for the post :)
January 18, 2019 at 11:43 pm
Ha! No worries, your comment was a useful prod for me to get that post done and published.
January 23, 2019 at 4:28 pm
[…] Birds have little blobs of tissue sticking out on either side of the spinal cord in the lumbosacral region (solid black arrow in the image above). These are the accessory lobes of Lachi, and they are made up of mechanosensory neurons and glycogen-rich glial cells (but they are not part of the glycogen body, that’s a different thing that lies elsewhere — see this post). […]
January 11, 2021 at 8:24 am
[…] Atterholt on weird neural canal stuff in dinosaurs, I realized that I needed to know more about glycogen bodies in birds, and about bird spinal cords generally. I expected that to be quick and easy: read a […]
May 16, 2021 at 7:27 am
[…] in contrast to the recess for the glycogen body, which is colored in blue in the chicken photo. Glycogen bodies, like the egg-shaped one in the […]