The development of the human body; a manual of human embryology . gn of de-velopment visible in the testis is a multiplication of the epithelial cells to form a thicklayer, into the under surfaceof which deep bays extendfrom the subjacent mesen-chyme, producing the appear-ance of cords of cells extend-ing into the mesenchyme fromthe epithelium. These cords(Fig. 202, ec) consist of twokinds of cells, (1) elongatedcells with a small amount ofprotoplasm, the epithelialcells, and (2) large sphericalcells with more abundant,clear protoplasm, and termedsexual cells. While the development isat this s
The development of the human body; a manual of human embryology . gn of de-velopment visible in the testis is a multiplication of the epithelial cells to form a thicklayer, into the under surfaceof which deep bays extendfrom the subjacent mesen-chyme, producing the appear-ance of cords of cells extend-ing into the mesenchyme fromthe epithelium. These cords(Fig. 202, ec) consist of twokinds of cells, (1) elongatedcells with a small amount ofprotoplasm, the epithelialcells, and (2) large sphericalcells with more abundant,clear protoplasm, and termedsexual cells. While the development isat this stage,—that is, atabout the fourth or fifthweek,—a structure makes itsappearance which serves to characterize the organ as atestis. This is a layer of connective tissue which grows inbetween the superficial and deep layers of the epitheliumand gradually extends around the entire organ to formthe tunica albuginea. Shortly after its appearance thecords of cells become broken up into more or less sphericalmasses by the growth into them of the surrounding mesen-. Fig. 201.—Reproductive Or-gans of a Female Embryoof Six Months. B, Bladder; F, Fallopian tube;/, intestine; 01, ovarian liga-ment; Ov, ovary; Rl, roundligament; UA, umbilical ar-tei y ; Ur, ureter; Ut, uterus;W, Wolffian body (epoopho-ron).—(Adapted from Mihal-kovicz.) THE TESTIS. 373 chyme, and into the substance of the testis there growfrom the capsules of Bowman in the neighboring portionsof the mesonephros cords of cells which form what areknown as the medullary cords (Fig. 202, mc). One of thesecords comes into relation with each of the spherical massesderived from the epithelium, and the cells of each mass,both the epithelial and the sexual, arrange themselves ina layer surrounding the enclosing wall of mesenchyme, al- f£?J\
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
