x16 transcripts are first detected during oogenesis, primarily in the nurse cells. As oogenesis proceeds, transcripts are detected in the oocyte, indicating that they are transported from the nurse cells to the oocyte. x16 transcripts are detected ubiquitously in early embryos, but localized expression is detected following the onset of zygotic expression. By embryonic stage 11 transcripts are detected in the neurectoderm and become increasingly localized to the central nervous system until the completion of embryogenesis. During larval stages, transcripts are expressed at low levels in a ubiquitous pattern, but in the imaginal discs, localized expression is noted.

x16 protein is ubiquitously expressed at embryonic stage 5. At later embryonic stages, it is highly expressed in the CNS.