1. Defect And Excess Of Formation

Arrest of development occurs in various forms and degrees.

Complete defect is a very rare occurrence; we may meet with it accompanying a very imperfect development of the kidneys, with absence of the urethra, and commonly also as a complication of formative defects of other organs. If, under these circumstances, the ureters are well formed, they open at the navel, into the rectum, or the vulva.

Occasionally the bladder is very small, whilst the other portions of the urinary apparatus are of normal size; its parietes are then imperfect; it is, in fact, represented by a delicate mucous bag, a mere dilatation of the ureters.

The various fissures of the bladder are other forms of arrest of development. We allude, first to the very rare cases of fissure or division of the bladder by means of a perfect or an imperfect partition in the median line, the so-called double bladder. That variety of this species of defect is much more frequent, which has been termed, from its appearance, ectrophia or inversion of the bladder. It is the result of a fissure, or a defect of the anterior vesical parietes, and is not unfrequently associated with fissures of adjoining viscera in the mesian line. It is more particularly accompanied by a defect of the symphysis pubis - in the female sex by absence of the anterior commissure of the labia and the clitoris; in the male sex, by fissure of the urethra on the dorsal surface of the penis, or epispadiasis. In the case of inversion of the bladder, we find in the hypogastrium, immediately beneath the navel, which is always placed very low, a red, mucous, dilated spot, the edges of which coalesce with the common integument: in the male sex it passes downwards, so as to terminate in the fissure of the urethra; in the female it is surrounded by two diverging tumors which represent the labia, and it terminates in the lamina of the general integument which invests the rima vulvae. The ureters open upon this mucous surface, and their orifice is generally found at the inferior half.

The exposed vesical mucous membrane and, owing to the constant stilli-cidium of urine from the ureters, the neighboring cutaneous surface, become irritated, reddened, and excoriated. In a very old preparation taken from an adult, which has been transferred from the Anatomical Museum of the University to the Pathological Collection, I find the former in a state of fungoid degeneration.

When the fissure of the urinary bladder occurs in an opposite direction, and is accompanied by fissure of the genital cavities and the rectum, we obtain the formation of cloacae in their various degrees. The urachus may remain patent to a certain distance from the bladder, or throughout its entire extent.

"We have also to allude to defective development occurring in the shape of unusual contraction of the vesical orifice, or atresia vesicae.

In biventral monsters, the bladder is found more or less competely double.