. Journal of anatomy. are uniformly distributed, so that even in theregion of the neck a marginal zone is no longer recognisable. On the otherhand, in the region of the tuber cinereum, immediately anterior to theneck of the infundibular process, typical mantle and marginal layers aredifferentiated. It thus appears that the infundibular process arises as a diverticulumof the diencephalic floor, whose walls undergo differentiation into ependymal,mantle (nuclear), and marginal zones similar to those of the brain wall. 228 Dv Katharine M. Parker Subsequently^ however, the walls of the pars neurali
. Journal of anatomy. are uniformly distributed, so that even in theregion of the neck a marginal zone is no longer recognisable. On the otherhand, in the region of the tuber cinereum, immediately anterior to theneck of the infundibular process, typical mantle and marginal layers aredifferentiated. It thus appears that the infundibular process arises as a diverticulumof the diencephalic floor, whose walls undergo differentiation into ependymal,mantle (nuclear), and marginal zones similar to those of the brain wall. 228 Dv Katharine M. Parker Subsequently^ however, the walls of the pars neuralis undergo modification,becoming more fibrous than those of the brain. As already seen inTrichosurus (Stage XI.), it later undergoes further changes due to theingrowth of connective tissue and cells of the pars infundibularis. Fevdineles iiasuta.—Apart from details of no apparent importance,such as the ditterences in the shape of the hypophysis in some stages, the. Fig. 41.—Stage J. Dasyurus viverrinus. Median longitudinal section through h3]iophysis. SI. 1-2-7. , chroniophilic cells; , dura mater; Ep., ependyraa ; L., lumen; , marginal zone: ,nuclear zone ; , pars distalis ; , pars infundibularis ; , pia mater ; , pars tuberalis. development of the pituitary body in Perameles closely resembles thatof Trichosurus. The differentiation of proximal and distal lobes and theprocess of formation of glandular tissue follows the same course as inTrichosurus. It is interesting to note that, in spite of the marked development ofSeessels pocket in Perameles nasuta (13, VII. 05), Stage IV., described inSection I. of this paper, there is no trace of this structure in any subsequentstage. The Development of the Hypophysis Cerebri, etc., in Marsupialia 229 The relations of the meninges to the various parts of the hypophysis ina Perameles pouch young of 35 mm. , 185 nnn. , are precisely thesame as in Trichosurus, Stage
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
