KALAMAZOO, MI - William U. Parfet unceremoniously resigned Wednesday from the Stryker Corp. Board of Directors and the company is not saying why.

Parfet, 69, was among the longest-tenured members of the board, which works on behalf of company stockholders to establish corporate policies, to provide oversight and guidance to the company's top management, and to make decisions on major corporate issues. Parfet joined the board in 1993.

"On Aug. 31, 2016, William Parfet resigned as a director of Stryker Corp. effective immediately," the Kalamazoo-based company stated in an email response to questions about the resignation.

Asked why he was resigning, Jenny Braga, senior manager of communications for Stryker, stated in an email that the company had no further comments on the matter.

The board continues with eight members.

In a regulatory filing, Monsanto Co. stated that Parfet also resigned Wednesday from that company's board. Monsanto is a Missouri-based provider of agricultural products intended to improve farm productivity.

The St. Louis Post Dispatch reported online that Monsanto disclosed Parfet's resignation in a regulatory filing but did not give a reason for his departure. Parfet had been a member of that board for 16 years.

Parfet, who was until recently the chairman and chief executive officer of Mattawan-based drug and chemical testing laboratory MPI Research, has been embroiled in a sexual harassment lawsuit filed on Aug. 1 in federal court in California.

The lawsuit alleges Parfet demanded to have sex with Shuang Zhang while she worked for him as a hired consultant in China and as a full-time employee of MPI Research on occasions while they were on business trips overseas and in the United States. She is a resident of Sunnyvale, Calif.

In the lawsuit, Zhang, who is described as being 27 years younger than Parfet, claims her two young children (ages 4 and 7) are the result of an affair that began with him in 2008 and continued until June of 2014.

The civil lawsuit alleges sexual harassment, sex discrimination and wrongful termination. An attorney for Parfet stated that he will present a vigorous defense to the lawsuit but has otherwise offered no public reaction to the legal action.

Parfet is married and has six children, four with his first wife and two with his current wife. He is the great-grandson of W.E. Upjohn, founder of The Upjohn Co., the Kalamazoo-based pharmaceutical company that is now a part of Pfizer Inc.

He sold his interests in MPI Research late last year and is executive chairman of inviCRO, a Boston-based provider of imaging solutions for drug development companies.

During his 23 years on the Stryker board, Parfet served as non-executive chairman of the board in 2012 as that company sought to find a replacement for then-CEO and Chairman Stephen P. MacMillan. The company stated that MacMillan, who was in the throes of a divorce, stepped down "for family reasons."

Not counting Stryker Chairman Emeritus John W. Brown, the only individuals with longer tenure on the board are: Howard E. Cox. Jr., a special limited partner with California-based venture capital firm Greylock Partners; and Ronda E. Stryker, granddaughter of Stryker Corp. founder Dr. Homer Stryker and vice chairwoman of Greenleaf Trust bank. Cox has been a director since 1974, Ronda Stryker since 1984.

Stryker Corp. is a maker of medical technologies, including orthopedic implants such as replacement hips and knees for people, powered surgical instruments used in operating rooms, and many of the hospital beds and gurneys found in U.S. health centers and emergency response vehicles.

It reported more than $9.9 billion in sales last year and is led by Chairman and CEO Kevin A. Lobo. It has approximately 3,000 employees in Kalamazoo County. They are part of a worldwide corporate workforce of about 27,000 employees.