Pastori declared her intention to study medicine, which was summarily forbidden by her mother.
Pastori was tutored in mathematics, physics, and chemistry, among other subjects by her sister Maria (who would later go on to become a mathematics professor), prior to attending the University of Milan and the University of Pavia.
After her doctorate she took a job at the University of Milan, where she started research into histology.
She was later granted a scholarship from the Italian Medical Women's Association, which afforded her access to the histology laboratory at the University of Rome.
In 1930 Pastori became a lecturer of histology and professor of biology at the Università Cattolica del Sacro Cuore.