Harvard Medical School has eliminated its pathology department and moved two growing departments to other real estate on campus amid pressure to accommodate the space needs of expanding departments, according to a recent letter sent to faculty by Medical School Dean Jeffrey S. Flier.

The Medical School had expected to move several of its departments into the Allston campus, but given the indefinite freeze on construction, Flier has had to find other options.

Researchers in the pathology department have been reassigned to other divisions within the schools and will continue their research under the auspices of their new departments.

Under the new arrangement, the department of Microbiology and Molecular Genetics will be renamed the Department of Microbiology and Immunobiology and will include many of the pathology department researchers.

The new department will be housed in the $260 million New Research Building, which opened in 2003.

The change will expand what had been a fairly small department into a larger one, bringing researchers from different disciplines together under the same roof, which administrators hope will lead to innovative research and collaboration.

But the academic shuffle has raised fears that the bureaucratic reorganization could disrupt what had been a highly productive unit at the Medical School.

“What I will say is that Microbiology and Molecular Genetics is a tight-knit, close, and I think very productive department, and my hope is that the changes don’t disrupt that dynamic,” said Lee Gehrke, a professor in the department and Quincy House Master.

His colleague, Jonathan R. Beckwith ’57, said while his own research might benefit from the move, he thinks interdisciplinary innovation is not predicated on collapsing departments.

“I’m just not particularly certain that it’s going to be particularly productive between people in different disciplines any more than they interact now,” Beckwith said. “It’s going to make it a significantly bigger department, and we liked our relatively small intimate department—people are a bit disappointed with that.”

The departments of Neurobiology and Systems Biology, both of which need additional space to expand, will take over the space that the Microbiology and Molecular Genetics department will vacate.

That should relieve some of the pressure on the Neurobiology department, which had wanted to expand but was unable to in the face of fiscal and space constraints in recent years, according to department chair Michael E. Greenberg.

—Staff writer Elias J. Groll can be reached at egroll@fas.harvard.edu.

—Staff writer William N. White can be reached at wwhite@fas.harvard.edu.