Button's heartbeat sounded really strong at 155 beats and s/he waved at us through the monitor. We inquired about finding out the sex of the baby. Linda, the sonographer, said it was rare to see anything at 13 weeks and even if she did, she wouldn't call it because she wouldn't want to risk being wrong. For now, I'll go on record to say that I think Button is a girl.
This first image is a profile (3/4 view) of Button. I've labeled it, so hopefully it's clear about what's what.