. The development of the albino rat, Mus norvegicus albinus. Embryology -- Mammals; Rats. Fig 1 Oviduct and ovum of albino rat, in 2-ccll stage, with first two blasto- meres separated. Rat No. 60, 1 day, 18 hours, after the beginning of insemina- tion. X 200. A, epithelial wall of oviduct with adjacent mucosa, and the fourth of a series of six sections of the 2-ccll stage with separated blastomeres, showing them in their relation to the epithelium. B, the series of six sections which pass through the separated blastomeres, the fourth of which is shown in A. The series reads fi'om right to left
. The development of the albino rat, Mus norvegicus albinus. Embryology -- Mammals; Rats. Fig 1 Oviduct and ovum of albino rat, in 2-ccll stage, with first two blasto- meres separated. Rat No. 60, 1 day, 18 hours, after the beginning of insemina- tion. X 200. A, epithelial wall of oviduct with adjacent mucosa, and the fourth of a series of six sections of the 2-ccll stage with separated blastomeres, showing them in their relation to the epithelium. B, the series of six sections which pass through the separated blastomeres, the fourth of which is shown in A. The series reads fi'om right to left. as shown in B and C of figure 1, Part I. There is here clearly a separation of the first two blastomeres and not a close approxi- mation of two unfertilized ova. In all of the unfertilized ova met with in the oviducts in the series at my disposal, these pre- sent the second maturation spindle and oolemma and are not to be confused with the blastomeres of the 2-cell stage, either as to size or structure. Both of the blastomeres in the prepara- tion under consideration present normal protoplasmic structure, having a finely granular i)rotoplasm. Their nuclei, as may be seen from the figures, are of normal size and structure. They pre- sent regular form, are distinctly membranated, have large chro- matoid nucleoli, and chromatin scattered in fine granules and threads. However, attention needs to be drawn to the presence of two micro-nuclei, one in each of the two blastomeres, showing in the third and fourth section of the series respectively (B, fig. 1). These micro-nuclei are nearly free from chromatin, each presenting a small chromatoid nucleolus. They are not to be regarded as cell inclusions, as perhaps representing phagocytic leucocytes. It may be conjectured that they were formed by amitotic division, by budding and constriction from the parent. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - color
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Keywords: ., boo, bookleafnumber124, bookpublisherphiladelphiapa, bookyear1915
