. A Reference handbook of the medical sciences : embracing the entire range of scientific and practical medicine and allied science. l Cord of an Embryo of 21 mm.;X 540 diameters ; stained with alum, cochineal, and eosine. about them, forming main cell I notice also afew cells, which I suppose to be leucocytes, but see no * Compare the article Yolk-sac; also Fig. 1276, vol. iii., p. 192, whichshows the yolk stalk within the umbilical cord. t The ectoderm is often wanting, owing to its frequent destructionpost mortem. % It is possible that the reticulum here described as cellular is, i
. A Reference handbook of the medical sciences : embracing the entire range of scientific and practical medicine and allied science. l Cord of an Embryo of 21 mm.;X 540 diameters ; stained with alum, cochineal, and eosine. about them, forming main cell I notice also afew cells, which I suppose to be leucocytes, but see no * Compare the article Yolk-sac; also Fig. 1276, vol. iii., p. 192, whichshows the yolk stalk within the umbilical cord. t The ectoderm is often wanting, owing to its frequent destructionpost mortem. % It is possible that the reticulum here described as cellular is, in part,at least, composed of remnants of an early matrix, which shrinks up andis replaced by the clear matrix here described: my observations do notsettle this question of the nature of the reticulum. 389 Umbilical REFERENCE HANDBOOK OF THE MEDICAL SCIENCES. other structures. By the end of the third month thecells have assumed nearly their definite form ; the proto-plasm has increased in amount and forms a large cell-body around each nucleus (Fig. 4247). The net-work hasbecome simplerand coarser, the ,J^ ^X^.^.f^. filaments fewerand thicker; in the matrix are numer-ous connective-tis-sue fibrils, not yetdisposed in bun-dles except hereand there ; as theycurl in all direc-tions, many ofthem are cut trans-versely and there-f o r e appear asdots. In oldercords there is anobvious increasein the number offibrils, and theyform wavy bun-dles. In the cordat term the matrixcontains mucin,and may be stainedby alum hema-toxylin ; at whatperiod this reac-tion is first de-veloped I havenot ascertained. Ihave observednothing to indi-cate the presenceof special lymph-channels in thecord at any period, but I have not investigated the point. Taitschannels are merely the intercellular spaces. The ectoderm is at first a single layer of cells, a con-dition which is permanent over the amnion ; in an em-bryo of three months I find the two-layered stage (). The outer layer is gr
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectmedicine, bookyear188
