On the Deverlopment of the Elastic Fibre in the Middle Ear of the Japanese Embryos

Abstract

The author investigated the development of the elastic fibre in the auditory organ of 40 human embryos and ascertained the following facts:
1) The development of the elastic fibre is not recognized at least until the 10th fetal week. The Fibre appears at first in the capsular ligament of the articulatio incudomalleolaris and the articulation incudostapedis after the 3rd fetal month.
2) The Fibre develops on the tympanic membrane after the 5th fetal month just beneath the epidermis of the pars flaccida. In the membrana propria of the pars tensa, it grown during the first 5th fetal month, mostly connected round the umbo of the tympanic membrane and along the periphery.
3) The development of the fibre in the lig. incudis post. et sup. and lig. malleolaris sup. takes place in the course of the 3rd fetal month, and its growth in the region of the lig. malleolars ant. et ext and other ligaments of the bones of the middle ear begins after the 5th fetal month.
4) The growth of the fibre in the capsular ligament of the articulatio mcudo-mallcolaris as well as the articulatio iucudo-stapedis takes place during the last half of the 3rd felal month.
5) The fibre in the lig. annulare baseos stapedis grows during the last half of the 3rd fetal month at the anterior pol in the internal ear side, and then uniformally over, and then a little later its growth reaches towards the middle ear side. Aluthough the amount of the fibre in the internal ear side is naturally greater in number than those growing in the middle ear side, the later is outstripped after the 5tn fetal month.
6) The fibre appears at first during the last half of the 3rd fetal mouth all over the secodary tympanic membrane.
7) The growth of the fibre in the membrana propria of the enchstachian tube takes place between the 3rd and the 5th fetal month.