Ultrastructural observations on stumpy (stm), a new chondrodystrophic mutant in the mouse.

Stumpy (stm) is a new chondrodystrophic mutant in the mouse. Light microscopy of cartilage reveals a slightly increased mitotic rate, more chondrocytes than is usual per lacuna and a wide zone of hypertrophy. Electron microscopy shows that many chondrocytes are in close approximation with some tight junctions: in cartilage from 14-day-old mice there is much interdigitation and folding of the cell membranes of adjacent chondrocytes.