. The American journal of anatomy . years. In these fetus of the eleventh week the basilar part of the ponshas reached a thickness of mm. (fig. 6). The abducens nerverootlets are almost entirely surrounded by nuclear material afterthey leave the tegmentum, only the caudal two or three fasciculibeing free. Great numbers of neuroblasts are encountered pass-ing between the seventh and eighth nerves, forming a mm. deep, while the germ centers at the ventricular marginare busily producing new cells. A fortunate sagittal sectionthrough No. 96 has been illustrated to show the participa
. The American journal of anatomy . years. In these fetus of the eleventh week the basilar part of the ponshas reached a thickness of mm. (fig. 6). The abducens nerverootlets are almost entirely surrounded by nuclear material afterthey leave the tegmentum, only the caudal two or three fasciculibeing free. Great numbers of neuroblasts are encountered pass-ing between the seventh and eighth nerves, forming a mm. deep, while the germ centers at the ventricular marginare busily producing new cells. A fortunate sagittal sectionthrough No. 96 has been illustrated to show the participationwhich the greatly thickened lateral recess wall takes in contribut-ing cells to the pons. For purposes of orientation a wax-platereconstruction was made with the section drawn on its cut sur-face (fig. 8). As the cerebellum in its growth crowds against themedulla, this caudal wall is flattened out and becomes part of themesial wall of the recess. A separation of the cells coming from 42 CHARLES R. ESSICK Caudal Wall of Lai T~ ^ . ■ Fig. S Sagittal section through the cerebellum and lateral recess of a 50 from a wax-plate reconstruction. X 15. (No. 96). DEVELOPMENT OF THE NUCLEI PONTUS IN MAN 43 the recess wall from those of the ventricular roof is purely arbi-trary, since the two origins are really continuous with each association in the adult was first pointed out by Orzechow-ski (08, p. 41). For embryological reasons the nuclear thicken-ings of the lateral recess wall with their accompanying fibersoccurring in the adult should be included in the structure which Ihave termed the corpus ponto-bulbare. At this stage the cavityof the fourth ventricle shows a peculiar tendency to form smalloutpouchings along the attachment of the roof at the place wherethe pontine nuclei are being formed. From two to four suchrecesses can be made out extending laterally for a considerabledistance from the main ventricular cavity and causing the exter-nal surface to b
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1912
