Aired Sunday December 10, 5:35pm - 6:00pmon E4

The Big Bang Theory

Series 12 Episode 12: The Propagation Proposition

Penny's ex-boyfriend Zack learns that he is infertile, so he asks Leonard for help. Then, Koothrappali attempts to mend things with his ex-fiancee Anu.

Original air date
Cast and crew
  • Mark CendrowskiDirector
  • Johnny GaleckiLeonard Hofstadter
  • Jim ParsonsSheldon Cooper
  • Kaley Cuoco-SweetingPenny
  • Simon HelbergHoward Wolowitz
  • Kunal NayyarRaj Koothrappali
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