It is a very interesting study with potential findings that could lead to significant judgments as the sex/age variables are related to muscle pain in TMD cases.
I have only a few comments:

1) In objectives, you wrote: "To investigate nerve fibers densities and the expression of NR2B-receptors, SP and NGF 32 in the fibers and to compare it between different tissue in the muscle, between sex and between age'. What do you mean by different tissue???

2)Please consider rephrasing the last sentence of your conclusion under "abstract".. THis is just exploratory and should be only in the discussion chapter as a suggestion for potential future studies..

3) Why apply DC/TMD criteria if they were asymptomatic? facial pain was an excluding criteria...

4) I noticed very few participants over 40, even 60 years when looked at Figure 3, how could these "outliners" influence your findings?

5)Just a curiosity: how the microtrauma caused by the punction technique could lead to an immediate tissue reaction and jeopardize the analysis???

6)In the first paragraph of the discussion, the term myalgia ( which is the DC diagnostic category) should be replaced by muscle pain, a more generic term...the same on line 223...