During the past year, Bast1 presented a complete account of the development of the fissula ante fenestram, a structure of interest in that in this area the bony changes known as otosclerosis most frequently occur. He traces its growth from its first appearance in the embryo to its full development. Fifty-five human fetuses were studied. The youngest specimen to show a fissula was a fetus of 43 mm. crown-rump length, or one approximately 8 weeks old. In this embryo the otic capusle was still mainly precartilage, and the scala tympani and scala vestibuli were just appearing on the inner side of the stapes. The fissula was represented by a small evagination of loose tissue anterior to the foot plate of the stapes. A little later it was well marked at the vestibular end, while closer to the middle ear it was represented by a mere strand of spindle cells.
DICKIE JKM. CHRONIC PROGRESSIVE DEAFNESS, INCLUDING OTOSCLEROSIS AND DISEASES OF THE INNER EAR. Arch Otolaryngol. 1934;19(6):712–736. doi:10.1001/archotol.1934.03790060061009
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