Shiva Purana
पंचरात्रेण कलिलं बुद्बुदाकारतां व्रजेत् ॥ बुद्बुदस्सप्तरात्रेण मांसपेशी भवेत्पुनः॥ १७॥
In five nights the foetus assumes the shape cf bubbles and the bubbly mass becomes muscular mass in seven nights.
english translation
paMcarAtreNa kalilaM budbudAkAratAM vrajet ॥ budbudassaptarAtreNa mAMsapezI bhavetpunaH॥ 17॥
hk transliteration by Sanscript