File:Thomson1919 fig05.jpg
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Fig. 5. Human ovum in discus proligerus exhibiting process of extrusion of the second polar body
x 600.
In fig. 5, thickness of section 0.007 mm, stained with Kernschwarz, the nuclear mass abuts against theinner surface of the Zona pellucida, the vitelline membrane, if this be regarded as a separate structure, alone intervening. In this section the nucleus appears as if possessed of a distinct membrane, but this appearance is most probably an optical effect due to the difference in the refractive index of the material lying within the nucleus (the karyoplasm) and the cytoplasm. The karyoplasm, which is paler and less granular than the surrounding cytoplasm, is retracted, leaving a narrow space around it, this may be an artefact (the specimen was hardened in formol) or it may contain what has been described as the karyo-lymph or nuclear juice. Within the nuclear vesicle is a deeply stained granule measuring about 0.008 mm in diameter, this exhibits a definite structure, having within it a paler sphere, to the side of which nearest the Zona pellucida is a more highly refractive granule. The whole nuclear vesicle measures 0.024 x 0.020 mm. The cytoplasm of the egg exhibits a remarkable appearance. Around its periphery it appears darker and more compact. Centrally, however, it becomes looser in texture, and the mitochondrial grains stain deeper and stand out more clearly. Near its centre is a spherical granule possibly the centriole, and what seems like vacuoles occur Within the substance of this less compact cytoplasm. The significance of this arrangement will be better understood, if now we examine the sections before and after this example.
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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding. (More? Embryology History | Historic Embryology Papers) |
- Human Ovum Links: Fig 1. Prophase I | Fig 2. | | Fig 3. | Plate 10 | Plate 11 | Plate 12
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Nature Obituary 1935 - Prof. Arthur Thomson (1858 - 1935)
Nature 135, 295-295 (23 February 1935) | doi:10.1038/135295a0 |
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Reference
Cite this page: Hill, M.A. (2024, March 19) Embryology Thomson1919 fig05.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Thomson1919_fig05.jpg
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
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