Smooth ER (Smooth endoplasmic reticulum) is a structure (cell organelle) which is primarily associated with the synthesis of proteins, lipids, phospholipids and steroids.
Mammals give live birth to their offspring. Reptiles and amphibians lay eggs. Mammals are also usually warm blooded while reptiles and amphibians are cold blooded. Most amphibians and reptiles abandon their young at a certain age while most mammals will take care of their offspring forever.
