The early development of the marsupialia, with special reference to the native cat (dasyurus viverrinus) / by J.P. Hill.

  • Hill, J. P.
Date:
[1910?]
Catalogue details

Licence: In copyright

Credit: The early development of the marsupialia, with special reference to the native cat (dasyurus viverrinus) / by J.P. Hill. Source: Wellcome Collection.

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    vations of Van der Stricht [’03, ’05] on the structure and polarity of tlie ovum of the bat (Vesperugo noctula), since these observations are in essential agreement with my own on the ovum of Dasyurus, and enable me to affirm that the polar differentiation herein recorded for the first time for the Marsupial ovum is attained as the result of vitellogenetic processes, which essentially correspond with those of the ovum of the bat. Van der Stricht, as is well known, has made a special study of the process of vitellogenesis in the Eutherian ovum, and is, indeed, at the present time the foremost authority on this particular subject, so that his views are worthy of all respect. Study of the oocyte of Vesperugo during the period of growth shows, according to Van der Stricht, that “ a un moment donne du developpement du jeune oeuf, les boyaux et amas vitellogenes [derived, according to him, from ‘ une couche vitellogene, mitochoudriale,’ present in the young oocyte in the first stage of growth] disparaissent au profit du vitellus, dont la structure pseudo - alveolaire s’accentue graduellement.” The full-grown oocyte at the stage just prior to the appearance of the first polar spindle is charac- terised by the presence of this “ pseudo-alveolar structui’e ” throughout the extent of its cytoplasmic body. The alveoli or vacuoles are of variable size, are filled by a clear liquid, and “ correspondent incontestablement au deutoplasma de I’oeuf. A ce stade du developpement de I’oocyte, ce vitellus nutritif, auquel s’ajoutent bientot des granulations graisseuses, est repandu uniformement dans toutes les profondeurs du cytoplasme. Nulle part on ne constate une zone deutoplas- mique distincte d’une zone de vitellus plastique.” In Dasyurus the stage in vitellogenesis which almost exactly coiTesponds with that of the full-grown oocyte of Vesperugo just described is seen in oocytes not quite full-gi*own. In fig. 4 is shown an oocyte of Dasyurus (•26 x ‘20 inm. in diameter), in which the same pseudo-alveolar sti’ucture as described by Van der Stricht for the Vesperugo oocyte is perfectly distinct. Here, however, fatty particles are not