The early years of basement membrane research

The early years of basement membrane research were characterized by studies that attempted to define these structures histologically and to describe their tissue localization. In this chapter, we describe the early ultrastructural studies that provided a more detailed definition of basement membranes and of the adjacent cells that produced them. Following the isolation of cell-free basement membranes from the renal glomerulus by Krakower and Greenspon (1951), studies took a new direction in an attempt to answer questions of tissue localization of specific antibodies raised against these structures and of morphologic changes seen in disease states. As histologic changes of basement membranes in several pathologic conditions became recognized and the deposition of immunoglobulins in the glomerular basement membrane and the mesangium became a hallmark of renal pathology in diseases, such as poststreptococcal glomerulonephritis, membranous nephropathy, acute serum sickness, Goodpasture syndrome, and others, investigators in the 1950s and early 1960s began to ask a different set of questions: What are the antigenic components of basement membranes against which the antibodies are reacting, and what is their chemical composition? Are there antigenic similarities between streptococcal antigens and basement membrane protein components? Studies aimed at answering these questions led to the understanding of the ultrastructure of basement membranes, the development of experimental models of immunologic renal disease, and the isolation and characterization of their macromolecular constituents. At this point it would be appropriate to mention that in the literature, two terms are used to define the same structure, namely, basement membrane and basal lamina. The term "basement membrane" seems to be favored by pathologists and nephrologists, whereas "basal lamina" appears to be preferred by cell biologists. In this book we use the term "basement membrane." However, if we quote a study in which the term "basal lamina" was used, then we will use that term. A new term made its appearance in the last 15 years-"basement membrane zone." This term refers to the area below the proximal end of the basement membrane adjacent to the subbasement membrane connective tissue. Here, proteins originating in the connective tissue may enter the basement membrane proper or may lie adjacent to it. Such molecules will be discussed in Chapter 7. © 2005 Elsevier Inc. All rights reserved.