. The elements of Embryology,. IX.] THE ETHMO-PRESPHENOID PLATE. 231 posterior clinoid walls. But it is in front of the foremost of these that the most noticeable changes take place. From the mid-line of the coalesced trabeculse there rises up a high ridge, the ethmo-presphenoid plate. This plate is at first liighest behind. In front and below it sends out a process, the prenasal cartilage, which forms the cartilaginous basis on which the premaxillary region is moulded. 12. Development continues to be very rapid in these parts; and on the seventh day the anterior end of the ethmo-presphenoid p
. The elements of Embryology,. IX.] THE ETHMO-PRESPHENOID PLATE. 231 posterior clinoid walls. But it is in front of the foremost of these that the most noticeable changes take place. From the mid-line of the coalesced trabeculse there rises up a high ridge, the ethmo-presphenoid plate. This plate is at first liighest behind. In front and below it sends out a process, the prenasal cartilage, which forms the cartilaginous basis on which the premaxillary region is moulded. 12. Development continues to be very rapid in these parts; and on the seventh day the anterior end of the ethmo-presphenoid plate (Fig. 70, eth and ps) becomes its highest point and forms the retral spike of the ethmoid (Fig. 70, eth). ttiti. 'ink. bar Side View of the Caktilaginous Ceanium of a Fowl on the Seventh Day of Incubation. (From Parker.) â pn prenasal cartilage, aln alinasal cartilage, ale aliethmoid; immediately below this is the aliseptal cartilage, etk ethmoid, f'p pars plana, ps pre- sphenoid. fa palatine. j)g pterygoid, z optic nerve, as alisphenoid. g quadrate. s< stapes, /r fenestra rotundum. Aio horizontal semicircular canal, fsc posterior vertical semicircular canal: both the anterior and the posterior semicircular canals are seen shining through the cartilage. so supraoccipital. eo exoccipital. oc occipital condyle, tic notochord. mk Meckel's cartilage, ch cerato-byal. hh basi-byal. chr and ebr cerato- branchial. hhr basibranchial. The prenasal cartilage (Fig. 70, p-n) still points down- wards, and by this time are formed the alinasal cartilages (Fig. 70, alri) developed from the trabecular horns, and the aliseptal cartilages which enclose the inferior turbinals (Fig. 70). The basisphenoid grows outwards on each side to form. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Foster, Michael. London : Macmill
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherlondo, bookyear1874
