Abstract
The temporal bones of 45 japanese corpses ( 29 males and 16 females) from 19 days to 68 old ware collected, and, after planting the celloidin, the horizontal serial specimens of tissue were made.
So I studied the development of the cells of the petrous apex and the relation of the cells of surrounding portion to it with the following results.
1) No development of air cells was observed up to the baby of full 1 year old. The cells of petrous apex were seen first at about 20 years, and developed most markedly at about 50 years.
2) The pericarotid cells showed a high degree of development already at about 20 years, but in the vertical portion it was slight. There was seen no cell at the age of about 20, and showed the maximum development at about 30 years.
3) The perilabyrinthine and periantral cells had well growed at the age of about 20, and showed the maximum at about 50.
4) The rate of the cell appearance at each portions was that: at the petrous apex was 20% (1/5 of the whole), and it corresponded to 39.3% (about 2/5) of the well grown cases of the periantral cells. It clinically requires to take care that the infection would be concealed by the existence of the cells of the petrous apex
5) The cells of the petrous apex were usually seen in the cases with well grown periantral cells, but sometimes the perilabyrinthine cells existed even in the cases with the under-grown. Futhermore the cells of the petrous apex were showed in the cases with sclerotic mastoid.
6) The rate of cell appearance of both sexes at each portions was that: at the petrous apex it was 27.7% in male, and 5. 2% in female. Especially the development of cells up to the utmost apex was not observed in female.
7) The bilateral similarity in the same case was 50%, and so its symmetry and asymmetry was half.
8) The rate of bilateral development of cell was that: the left was slight dominant at the petrous apex but no difference was seen at other portions.
9) The cases in which the cells of the petrous apex reached to the utmost apex were 3 among 11. and they were all male. Its maximum distance from the front of horizontal canal was 2.5cm. The number of the cells of the petrous apex was from 1 to 6 at maximum.
