Figure 5.

Formation of resorption pits on cortical bone slices by cultured marrow cells from PGHS-2^+/+ mice (white bars) and PGHS-2^–/– mice (black bars). Cultures were treated with either vehicle (Control) or 1,25-D (10 nM) with and without PGE₂ (1 μM). An osteoclast resorption pit was defined as having multiple overlapping resorption lacunae. (a) Photomicrograph of resorption pits on cortical bone. (b) Number of resorption pits counted on 6 bone slices (mean ± SE). ^ASignificant difference from control group; P < 0.01. ^BSignificant difference from 1,25-D–treated PGHS-2^+/+ cells; P < 0.05. ^CSignificant effect of addition of PGE₂; P < 0.01.