. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Root Sheaths â External-- "-- Internal-"''! â I Papilla'". 7-Hair Bulb Dermal Papilla--^g Fig. 202. Six stages in the development of a hair. A and B, from embryo of a sheep. (After Schimkewitsch.) c and d, from a mole. (After Maurer.) e and f, from human embryo. (After Hertwig.) The first evidence of hairs in the mammalian skin is found in the form of concentrations of epidermal cells which, because of displacement resulting from their rapid
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Root Sheaths â External-- "-- Internal-"''! â I Papilla'". 7-Hair Bulb Dermal Papilla--^g Fig. 202. Six stages in the development of a hair. A and B, from embryo of a sheep. (After Schimkewitsch.) c and d, from a mole. (After Maurer.) e and f, from human embryo. (After Hertwig.) The first evidence of hairs in the mammalian skin is found in the form of concentrations of epidermal cells which, because of displacement resulting from their rapid multiplication, grow down like plugs into the corium (Fig. 202), and become hair follicles. The bulb of each follicle, with its surrounding inner and outer root sheaths, soon differentiates, and the newly formed lengthening shaft pushes out towards the surface, loosening the temporary epitrichium which at this stage covers the body like a gauzy envelope. The hairs in man first emerge at about the fifth fetal month, in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Walter, Herbert Eugene, b. 1867; Sayles, Leonard Perkins, 1902-. New York : Macmillan Co.
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
