Mammillaria in Fruit

One of the things I have been interested in lately is the timing of flowering and fruiting of M. dioica. I have blogged before about this cactus in my garden. I gave it some water in late September or early October, and it flowered by October 16. On Nov. 8 I first noticed that it had produced two fruit. Here's that photo:

Today it has 5 fruit and the last of the flowers is finishing up.

Based on this extremely small sample, it appears that M. dioica growing on the coast can bloom within 2-4 weeks after receiving water. It then goes to fruit 3-6 weeks after that.

I believe that this is quite different from tetrancistra which can delay fruiting for several months. Dioica in the desert may also behave differently. My next question is whether these fruit have viable seeds. If there are seeds, how easily do they germinate?