File:Streeter028.jpg

Fig. 28

Lateral view of wax-plate reconstruction of the left membranous labyrinth and the periotic spaces in a human fetus 85 mm. crown-rump length (Carnegie Collection, No. 1400-30), enlarged 11.4 diameters. The cistern and the connecting scala vestibuli are shown in green. Although the greater part of the cistern abuts against the stapes, it will be noted that it is also begiiming to spread over the liorsal surface of the utricle and along the inner border of the lateral semicircular duct. The scala vestibule communicates freely with the cistern and extends downward alotig the apical surface of the cochlear duct, throughout nearly two turns, showing the characteristic sacculated appearance near its tip, where the coalescence of the spaces is less complete.