. Text-book of embryology. Embryology. II BEAIN, 87 groove bounded behind and in front by a slightly projecting ridge— the rudiments of the optic chiasma and of the anterior commissure respectively (Fig. 53, eh, ). About stage 31 a little pocket-like diverticulum of the roof of the primitive fore-brain makes its appearance (Fig. 53, D, pin). This is the pineal body and its appearance is of topographical importance as serving to demarcate the primitive fore-brain roof into thalamencephalic and mesencephalic Fig. 52. —Brain of young Lepidosiren as seen from the left side. A, stage
. Text-book of embryology. Embryology. II BEAIN, 87 groove bounded behind and in front by a slightly projecting ridge— the rudiments of the optic chiasma and of the anterior commissure respectively (Fig. 53, eh, ). About stage 31 a little pocket-like diverticulum of the roof of the primitive fore-brain makes its appearance (Fig. 53, D, pin). This is the pineal body and its appearance is of topographical importance as serving to demarcate the primitive fore-brain roof into thalamencephalic and mesencephalic Fig. 52. —Brain of young Lepidosiren as seen from the left side. A, stage 26; B, stage 31; C, stage 35- ; D, stage 39. , cerebral hemisphere; /, primitive fold of brain-floor; inf, infnndibulum; , olfactory bulb; , olfactory tubercle; pin, pineal body; thai, thalamencephalon ; , tectum opticum. The lateral bulgings of the fore-brain have become more pro- minent and now project forwards beyond the limit of the rest of the fore-brain. In the mesial plane between the two hemispheres there projects upwards and forwards a little pocket of the anterior wall of the fore-brain. This is the rudiment of an organ of unknown significance—the paraphysis (Fig. 53, D, par). Soon after the appearance of the pineal body the roof of the' primitive fore-brain becomes divided into a posterior portion belong- ing to the mesencephalon and an anterior portion belonging to the thalamencephalon (Fig. 51, B, , and thai). As development goes. 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 MacBride, E. W. (Ernest William), 1866-1940; Kerr, John Graham, 1869-; Heape, Walter, 1855-1929. London : Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, bookpubli, booksubjectembryology
