I remember my doctor giving my mom a booklet on physical development with advice about how to talk to your kids about various subjects related to puberty.
It led to many an awkward discussion about how my body was changing, wet dreams, erections, and masturbation. My mom was always big on being open about puberty and sex. From about age 10-16, about once a week when she came in to say goodnight she'd ask how thing were going and if I had any questions. If I didn't she'd often bring something up.
On many of these occasions, she'd ask to see how I was developing. At first I was reluctant, and she didn't push me. When I started getting pubic hair, I oddly wanted her to see and be proud of me. That time when she asked to see me, I nervously got out of bed and pulled down my underpants.
After that, I grew more comfortable talking to her. I eventually slept naked, which made it easier when she wanted to see me.
To my dismay, she stopped around when I was 16. She saw me naked again at the doctor when I was 18 and a few time after that. She also helped me perform skin exams at home until I was in my 20s.