DEVELOPMENT. - The development of the male urethra is a subject of considerable interest both in a physiological and patho logical point of view, as a comprehension of the phenomena attending it enables us to offer a ready explanation of those curious mal formations to which this canal is not un frequently liable.
For the description of the development of the intra-pelvic portion of the urethra from the uro-genital sinus, the reader is referred to the article PROSTATE, in which the separa tion between the bladder and rectum in the male, and the bladder, rectum, and vagina of the female, is considered ; and we have, there fore, now only to trace the growth and exten sion of that portion of the urethra which traverses the body of the penis.
Up to the end of the fifth or beginning of the sixth week, the external organs of ge neration in the male resemble those of the female, and a common opening or cloaca exists, into which the rectum, bladder, and genital organs terminate. At the anterior part of this common outlet a small projection is formed, presenting a concavity below, along which there runs a superficial groove towards the anus. This corresponds to the clitoris in the female, and the penis in the male. A slight enlargement now takes place at the extremity, which becomes the glans. In the female the two sides of the groove begin to swell out, and become the labia majora. A separation now takes place between the open ings of the anus and vagina, and the perineum begins to be formed. The opening of the
uro-genital canal is a small aperture in front of the anus, at the extremity of a slit, which Proceeds as far as the root of the penis or clitoris, and becomes surrounded by two folds of skin which form its sides.
In the male, the two folds of skin which correspond to the labia majora become blended together, and form a projecting ridge, called the raphe ; they also form the scrotum. The penis continues to increase in size, but the groove which runs along its under-surface as far as the glans, remains patent until the four teenth or fifteenth week, when its sides swell out and adhere together, and hence the urethral canal, which is completed about the fifteenth week. The prepuce is formed at the fourth month, and at this period the orifice of the urethra appears in the form of a small slit at the extremity of the glans, but it is com pletely closed at first.
At the period of birth the pelvic portion of the urethra is more vertical than in the adult, in consequence of the position of the bladder, a great part of which is now situated in the abdomen ; the bulbous portion is situated at a greater distance from the anus than after wards.
The rudiments of Cowper's glands are formed at a very early period, on each side of the genitourinary passage.