The development of the human body; a manual of human embryology . os (A) of 6 cm. and (/?>)of CM. sixth months the lobes elongate into solid cylindrical col-umns of cells (Fig. 86) resembling not a little the cylinderswhich become converted into sudoriparous glands, andeach column becomes slightly enlarged at its lower end,from which outgrowths begin to develop to form the acini. 17- THE DEVELOPMENT OF THE HUMAN BODY. A lumen first appears in the lower ends of the columns andis formed by the separation and breaking down of thecentral cells, the peripheral cells persisting as the lining
The development of the human body; a manual of human embryology . os (A) of 6 cm. and (/?>)of CM. sixth months the lobes elongate into solid cylindrical col-umns of cells (Fig. 86) resembling not a little the cylinderswhich become converted into sudoriparous glands, andeach column becomes slightly enlarged at its lower end,from which outgrowths begin to develop to form the acini. 17- THE DEVELOPMENT OF THE HUMAN BODY. A lumen first appears in the lower ends of the columns andis formed by the separation and breaking down of thecentral cells, the peripheral cells persisting as the liningof the acini and ducts. The elevation of the gland area above the surface toform the nipple appears to occur at different periods indifferent embryos and frequently does not take place untilafter birth. In the region around the nipple sudoriparousand sebaceous glands develop, the latter also occurringwithin the nipple area and frequently opening into theextremities of the lacteal ducts. In the areola, as thearea surrounding the nipple is termed, other glands,. Fig. -Section through the Mammary Gland of an Embryo of 25 , Stroma of the gland.—{From Nagel, after Basch.) known as Montgomerys glands, also appear, their develop-ment resembling that of the mammary gland so closely asto render it probable that they are really rudimentarymammary glands. The further development of the glands, consisting of anincrease in the length of the ducts and the developmentfrom them of additional acini, continues slowly up to thetime of puberty in both sexes, but at that period furthergrowth ceases in the male, while in females it continuesfor a time and the subjacent dermal tissues, especially theadipose tissue, undergo a rapid development. LITERATURE. 173 r The occurrence of a milk ridge has not yet been observedin a sufficient number of embryos to determine whether it isa normal development or is associated with the formationof supernumerary glands {polymastia). This is by no meansan
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
