Study of the Morphology of the Osteoclasts from Rat Femura

Osteoclasts were isolated from femura of 2-4 days old rat, settled on cover glasses, maintained in the culture medium, and morphologically studied using a phase contrast microscope and a scanning electron microscope. Results obtained are as follows. 1. Osteoclasts in culture were classified into five types (Type I-Type V). Type I : The hemispherical cell or the disk-like one rised at the centre. Sometimes the cells have a lot of pseudopodia at the small part of the edge. Type II : The semicircular cell with many lamellipodia at the portion of arc and with a lot of pseudopodia at the portion of cord. Type III : Highly irregular flat cell, which are surrounded by lamellipodia. Sometimes a lamellipodia grew up to a trunk which is about 40μm in length. Pseudopodia are often seen between the lamellipodia. Type IV : The turned dish-like cell without any lamellipodia and pseudopodia. Type V : The round flat cell, which have numerous particles and nuclear in the cytoplasm. 2. The number of osteoclast in each type increased at first and then decreased in the course of culture time. The peaks of the cell number appeared the following order ; Type I, (Type II), Type III and IV, and Type V. In short, cultured osteoclasts which are obtained from rat femura were classified into five morphological distinct types, and changed rapidly and morphologically during 2 days of the culture period. The cells of Type III are resemble to the resorbing osteoclast, which were seen on the endosteum surface in vivo, and on the tooth in vitro.