A professional corporation may render professional services only through its officers, employees, and agents, who are duly licensed to render such professional services. However, this provision shall not be interpreted to prohibit the employment by a professional corporation of clerks, secretaries, bookkeepers, technicians, and other assistants who are not usually and ordinarily considered by custom and practice to be rendering professional services to the public for which the license is required. (1963, No. 218, § 8, eff. July 3, 1963.)