Does nmap mtu scan really send crafted mtu size?

edit

I've been reading about nmap techniques here as part of my network security syllabus ...

I've performed 2 scans ... one to port 1337 which is closed while the other port 4444 is open.

When I try nmap mtu scan and capture the packet with Wireshark, I don't see the mtu size (32) that I set in nmap.

user@linux:~$ sudo nmap --mtu 32 192.168.10.12 -p 1337

Nmap scan report for 192.168.10.12
Host is up (0.0023s latency).
PORT     STATE  SERVICE
1337/tcp closed waste
MAC Address: AA:AA:AA:AA:AA:12 (Unknown)

Nmap done: 1 IP address (1 host up) scanned in 13.13 seconds
user@linux:~$

The only value that I see is Total Length: 44

1. Any idea why I did not see mtu size 32 in Wireshark?

2. Is this the right place to check mtu size in Wireshark (IPv4 > Total Length)?