In situ localization of lectin‐binding glycoconjugates in the matrix of growth‐plate cartilage

Abstract

In the distal hypertrophic zone of growth-plate cartilage, the pericellular matrix surrounding individual chondrocytes and the territorial matrix uniting chondrocytes into columnar groups are invaded by metaphyseal endothelial cells prior to osteogenesis. In the present study, lectin-binding glycoconjugates were analyzed in these two matrix compartments of growth-plate cartilage from Yucatan swine. Nine lectin-fluorescein conjugates were tested by a postembedment method on 1-micron-thick, nondecalcified, Epon-embedded sections. Chondrocytes in all cellular zones were surrounded by a pericellular matrix which showed positive binding for peanut agglutinin (PNA), ricin agglutinin (RCA-I), and soybean agglutinin (SBA). Binding by these lectins was sensitive to digestion with hyaluronidase, chondroitinase, and trypsin. Pericellular glyconconjugtes that bind RCA-I and concanvalin A (CONA) after periodic acid oxidation, and which were sensitive to trypsin but not to chondroitinase or hyaluronidase, were present in the hypertrophic cell zone. Within the territorial matrix, binding of lectins specific for galactose, N-acetylgalactosamine, and fucose showed gradients of intensity which became maximal at the last transverse septum. Lectin-binding histochemistry more precisely differentiated the microheterogeneity of glycoconjugate distribution within these two matrix compartments than has been possible with other histochemical techniques. Lectin-binding affinity is a potentially useful technique by which to isolate cartilage matrix macromolecules unique to specific cellular zones of the growth plate.

Morphologic stages of the terminal hypertrophic chondrocyte of growth plate cartilage

“…Terminology for different matrix zones of growth plate cartilage will be consistent with that of Eggli et al (1985) and Farnum and Wilsman (1986). The longitudinal septa are the matrix areas between columns of chondrocytes, and it is the longitudinal septa that calcify in the distal hypertrophic cell zone.…”

“…The reserve cell zone, the proliferative cell zone, and the hypertrophic cell zone of the proximal radius of a 4week-old Yucatan pig are shown in Figure l a . Hypertrophic chondrocytes are those cells in which the proximodistal diameter is greater than one-half of the transverse diameter (Buckwalter et al, 1985;Farnum and Wilsman, 1986). The terminal hypertrophic chondrocyte is defined as a cell that in any given section is separated either from a n endothelial cell or from blood plasma by the distance of the last transverse septum.…”

A cell shrinkage artefact in growth plate chondrocytes with common fixative solutions: importance of fixative osmolarity for maintaining morphology

“…In the hypertrophic zone (between the proliferative zone and the zone of calcification) the cells were larger and frequently more rounded although there were cells with a height greater than the cell's width (Buckwalter et al, 1985;Farnum and Wilsman, 1986). In accordance with the visual appearance of chondrocytes along the growth plate, the quantified volume of in situ cells increased although it was clearly not a linear process as there was a relatively poor fit to a linear regression (correlation coefficient r 2 = 0.793).…”

Quantitative analysis of chondroitin sulphate retention by tannic acid during preparation of specimens for electron microscopy

“…Commercial collagen preparations have been reported to contain much afibrillar material (Farnum & Wilsman, 1986), which might interfere with the binding of GAGs to collagen (Koda & Bernfield, 1984). Crude collagen was purified by digestion with trypsin (Steven & Thomas, 1973;Minns & Steven, 1977), papain (Hardingham & Muir, 1974;McDevitt & Muir, 1976), and hyaluronidase (Enna & Zimny, 1974).…”