A comparative ultrastructural study of the mitotic chondrogenic cells in the mandibular condyle and tibial growth plate of the rat.

Mitotic cells in the rat mandibular condyle (proliferative mandibular cells) were compared with mitotic cells in the rat tibial growth plate (proliferative tibial cells). In the tibial proliferative cells, the rough endoplasmic reticulum mostly became vacuolated during the latter stage of mitosis, whereas the rough endoplasmic reticulum of the proliferative mandibular cells rarely underwent disorganization. Further, a wide area remained outside of the mitotic spindle in the proliferative tibial cells at the metaphase, while only a narrow area remained in the proliferative mandibular cells. This finding might account for the difference of disorganization of the rough endoplasmic reticulum.