A 46-year-old female patient

is found to be anemic during a preventive taking of blood. Despite a healthy

and varied diet, which the patient claims to follow, other findings in her

blood count, such as the presence of large erythrocytes (megalocytes) and low

levels of vitamin B12, make it look like anemia based on a deficiency of this

very important vitamin. Therefore, if the patient is taking enough of it in her

diet, the problem is likely to be in its absorption in the digestive system. In

order for this vitamin to be absorbed from the digestive tract into the blood,

it must be bound to an intrinsic factor in the stomach. Indeed, antibodies to

intrinsic factor have been demonstrated in this patient. Which cells of the

gastric glands produce this factor?