Board Thread:Warhammer 40k General Discussion/@comment-7699236-20150618150629/@comment-32638586-20170721000551

In technicalities female astartes exist to some extent with Honsou and his Daemonculba which is described on Lexicanium as such "The system began with the fattening of human female slaves, who were shackled in cages and force-fed nutrients, widening their bodies to grotesque proportions; these women became part of the Daemonculaba's birthing wombs. Their insides were altered and chemistry wired by the   Savage Morticians  (possibly members of the   Dark Mechanicus), utilising the captured gene-seed. The exact science is vague, but by taking an adolescent child and sealing him within the stomach of one of the enslaved women, the process would either transform the child into an   Astartes, or mutate horribly and create an abomination. Either way, the candidate is reborn later without flesh. If the freshly born creature passes inspection, the new recruit is clothed in flesh carved from human male slaves, whose skin had been stretched considerably to vast expanses. If it fails, the reject is cast out through the fortress' sewer system. Some of these rejects survive, however, and become scavenger-hunter creatures known as the   Unfleshed.

The system can also utilise the genetic material of harvested Iron Warrior corpses, which are broken down to be fed to the implanted child within the Daemonculabula."