D1 is an embryonic line made by Andreas Dübendorfer in the mid-1970s, when he was a post-doc in James Sang's laboratory. It is not in any way related to the imaginal disc line ML-DmD1.
Sex
D1 cells are male, by criteria of roX gene expression and Sxl splicing (Stoiber et al., 2016, G3, in press).