The development of the human body; a manual of human embryology . e on its ventral wall begins tothicken, producing a slight projection to the exterior. Thiseminence, which is known as the genital tubercle (Fig. 206,gt), rapidly increases in size, its extremity becomes some-what bulbously enlarged (Fig. 208, gl) and a groove, ex-tending to the base of the terminal enlargement, appearsupon its vestibular surface, the lips of the groove formingtwo well-marked genital folds (Fig. 208, gf). At about the THE EXTERNAL GENITALIA. 385 tenth week there appears on either side of the tubercle anenlargeme
The development of the human body; a manual of human embryology . e on its ventral wall begins tothicken, producing a slight projection to the exterior. Thiseminence, which is known as the genital tubercle (Fig. 206,gt), rapidly increases in size, its extremity becomes some-what bulbously enlarged (Fig. 208, gl) and a groove, ex-tending to the base of the terminal enlargement, appearsupon its vestibular surface, the lips of the groove formingtwo well-marked genital folds (Fig. 208, gf). At about the THE EXTERNAL GENITALIA. 385 tenth week there appears on either side of the tubercle anenlargement termed the genital swelling (Fig. 208, gs),which is due to a thickening of the mesenchyme of thelower part of the ventral abdominal wall in the regionwhere the inguinal ligament is attached, and with the ap-pearance of these structures the indifferent stage of theexternal genitals is completed. In the female the growth of the genital tubercle pro-ceeds rather slowly and it becomes transformed into theclitoris, the genital folds becoming prolonged to form the. Fig. 208.—The External Genitalia op an Embryo of 25 , Anus; g/, genital fold; gZ, glans; gs, genital swelling; p, perineal body. —(Keibel.) labia minora. The genital swellings increase in size, theirmesenchyme becomes transformed into a mass of adiposeand fibrous tissue and they become converted into the labiamajora, the interval between them constituting the the male the early stages of development are closelysimilar to those of the female; indeed, it has been wellsaid that the external genitals of the adult female resemblethose of the fetal male. In early stages the genital tuber-cle elongates to form the penis and the integument whichcovers the proximal part of it grows forward as a fold 386 THE DEVELOPMENT OF THE HUMAN BODY. which encloses the bulbous enlargement or glans andforms the prepuce, whose epithelium fuses with that cover-ing the glans and only separates from it later by a cornifi-cation o
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
