. The physical basis of heredity . Fig. 46.—Cells emerging from their last spermatagonial division, a. h\ passing into thesynapsis stage, c, d; (After Wenrich.) CROSSING OVER AND CHROMOSOMES 107 for the ordinary spermatogonia! (or somatic) cell-divi-sions. Each chromosome vesicle begins to show a coiledthread (Fig. 46, c). Each thread next becomes longerand longer (Fig. 46, d) until the whole nucleus is filledwith them. One or both ends can often be seen at thedistal pole of the cell, where deep-staining nucleoliare present. The cells are now in the so-called thinthread, or leptotene stages. T
. The physical basis of heredity . Fig. 46.—Cells emerging from their last spermatagonial division, a. h\ passing into thesynapsis stage, c, d; (After Wenrich.) CROSSING OVER AND CHROMOSOMES 107 for the ordinary spermatogonia! (or somatic) cell-divi-sions. Each chromosome vesicle begins to show a coiledthread (Fig. 46, c). Each thread next becomes longerand longer (Fig. 46, d) until the whole nucleus is filledwith them. One or both ends can often be seen at thedistal pole of the cell, where deep-staining nucleoliare present. The cells are now in the so-called thinthread, or leptotene stages. The threads next come together in pairs beginningat the distal end of the chromosomes (the zygotene stage,
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectheredit, bookyear1919
