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What type of muscle is it?

Hey guys,
Please could you help me with identifying what kind of muscle this is. It's either skeletal or cardiac. At first, I thought it was skeletal but now I have a feeling it's cardiac.
Thank you!

image1.jpg104.0KB

Reply 1

macpatgh-Sheldon

Hi sorry no-one has replied yet!

Let me try to help, although this light microscope view of a longitudinal section is a little confusing.

1. I for one cannot make out clear-cut striations, which would mean exclusion of both striated muscle [so-named cos of the transverse stripes [vertical in this pic]]AND cardiac muscle [the latter also has stripes].
2. There are no clear intercalated disks, which would also support (1) above.
3. Cardiac muscle cells are connected to one another by oblique bands [form syncytia - Greek "syn" OR "sym" means together OR "the same" as in "synopsis" OR "symphony" OR "synonymous" OR "symbiosis"] - cannot make out these except perhaps a few near the very top.
4. The cells are not spindle-shaped, so less likely to be smooth muscle.
5. There are a lot of spaces/gaps between myocytes, which is more commonly seen in smooth muscle.

Sorry if I am making things worse for you by introducing more confusion, but I would, on balance, place my bet on smooth muscle.

M.