Unsolved Problems in Cell Biology Biology 446 Sept 25, 2015 Albert Harris
Questions About Cartilage
The photograph below, & also the drawing below that, are borrowed from the Wikipedia article titled "Endochondral ossification". This consists of the replacement of cartilage by bone, combined with enlargement of the cartilage next to areas of bone formation. This process is very important, medically. Without it, bones can't elongate.
This color photograph shows a thin section through a piece of cartilage near one end of a rabbit's leg bone. The area stained green on the left side is bone that already existed. The greenish-purple areas on the right are rods of newly bone. The broad, pale area in the middle is hyaline cartilage. The approximately horizontal rows of dark blue dots are nuclei of cartilage cells. You can magnify this picture in the wikipedia article by typing command+ several times.
The sketch below is from that same Wikipedia article: Notice that it is slightly inaccurate; chondrocytes become gradually bigger, as the area of bone formation moves toward them.
(The sketch underestimates the volume increase, indicates that it is sudden, and begins very close to where bone begins to form). The photo shows what actually happens.
"electroosmosis is the motion of liquid induced by an applied potential across a porous material" and this same word also refers to the resistance of fluids to movement, when held back by electrical voltage.
http://www.albertkharris.com/cartilage.htm
Or Google " Electroosmosis cartilage " and read as much as you want.