Season 7 Episode 4

Title: Can't Fight Biology
Air Date: October 14, 2010 at 12:00 AM PDT

Remember the good ole days when it was just Meredith, Izzie, and George in one house? Now it's Meredith, Alex, Lexie, April, and Jackson. It's like a hospital hostel, and they're all jostling each other in the bathroom. And speaking of cramped quarters, Mark practically walks in on Arizona and Callie while the two of them are trying to share some special time. Meredith and Derek are at the obstetrician's office, and the doc tells them that Mer has a "hostile uterus." Mer takes this quite personally and is quite indignant about it. Read the full episode recap here.