Urethra development

Extremely rare in childhood, the urethral polyp is usually solitary and consists of a pedunculated structure, originating from the posterior urethra, developing in the bladder neck, which can prolapse in the urethra during micturition (Foster and Garrett 1986). Hematuria, nonneurogenic bladder-sphincter dysfunction and infection may reveal the abnormality. On ultrasound, it appears echo-genic. The main differential diagnosis of urethral polyp is an ectopic ureterocele that has ruptured either spontaneously (Fig. 6.8) or after endoscopic... 

The critical period for the induction of hypospadias by finasteride in rats is Days 16 to 17 of gestation (Clark et al., 1990a). It is unlikely that other agents would have a much earlier critical period since testosterone synthesis, which is required for the development of the penile urethra, begins in the rat on Day 15 of gestation (Habert and Picon, 1984). Thus, if treatment in the embryo-fetal development study... 

Reactive arthritis (ReA) develops 1-3 weeks after a bacterial infection in the intestinal tract (diarrhea) and/or urethra (urethritis) or elsewhere due to immune responses. HLA-B27 positive individuals may develop ReA. ReA is an autoimmune disease and consists of sterile axial and/or peripheral articular inflammation, enthesitis and extra-articular manifestations. 

The glands that produce sperm are the testes. Prior to copulation, the sperm are stored and undergo further development in the epididymis, located on the testicles. For delivery, sperm are incorporated into seminal fluid produced by seminal vesicles, the prostate gland, and the bulbourethral gland, and ejaculated through the urethra of the penis. The process of forming sperm and other male sexual functions and characteristics are promoted by testosterone, the male sex hormone. 

Timms BG, Howdeshell KL, Barton L, et al. Estrogenic chemicals in plastic and oral contraceptives disrupt development of the fetal mouse prostate and urethra. PNAS 2005 102(19) 7014-19. 

Simply stated, UI may occur only as a result of abnormalities of the urethra (including the bladder outlet and urinary sphincter) or the bladder, or from a combination of abnormalities of both structures. Abnormalities may result in either overfunction or underfunction of the bladder and/or urethra with the resulting development of UI. While this simple classification scheme excludes extremely rare causes of UI such as congenital ectopic ureters and urinary fistulas, it is useful in gaining a working understanding of the condition. 

Nielsen 2002). In rats, supplemental silicon (250 mg kg by DM) had no effect on skeletal development. Egg production in chicken receiving a basal diet containing from 0.6 to 143 mg Si kg DM was reduced insignificantly. Supplementation of the hens feed reduced egg production insignificantly (Vogt 1992). Normally, urinary silicon is readily excreted but, under some conditions in grazing steers and sheep, part of the urinary silicon is deposited in the kidneys, bladder, or urethra to form calculi (McDowell 1992). 

Fig. 1.9a-c. Anterior compartment, a Macroscopic preparation of a 23-week-old female fetus with the pubovesical ligament (arrow) and the tendinous arch (arrowhead). x9. b In an axial section (5 mm) of an adult female with the paravisceral fat pad (asterisks), x. c Axial section (400 pm) of a 24-week-old female fetus with the developing paravisceral fat pad (asterisks). X8. b, bladder u, urethra pbo, pubic bone oi, obturator internus muscle... 

Fig. 1.11 a) and the external urethral sphincter. As has been reported previously [37], this muscle is horse-shoe- or omega-shaped during fetal development and incompletely covers the urethra (Fig. 1.11). The dorsal ends of this muscle are connected by a plate of dense connective tissue that is small in the female where it is firmly attached to the ventral wall of the vagina (Figs. l.lOd, 1.11a). Whereas most of the fibers of the external urethral sphincter run semicircular, the most caudal fibers nearly run in a transverse plane. This portion predominates in the male and therefore has been considered as the male s deep transverse perineal muscle. However, it does not exist in the female [42].

An excessive uptake in soluble silica by cattle, unaccompanied by enough water to remove if from e system, can lead to stones or calculi in the urinary tract (210, 211), esp ially if concentration in the urine exceeds 70-80 ppm (212). Similarly, dogs fed on a diet high in silicate bulking constituents developed siliceous stones in the kidneys, bladders, and urethras (213). 

Variations of the arterial vascular supply to the corpus spongiosum, to the urethra and glans are common. Asymmetry of the dorsal arteries is often recognized (Fig. 5.6), in which one artery is well developed, T diile the other is small, or even atrophic (Chiou et al. 1999). 

Fistulae developing in the posterior urethra are better detected using voiding cystourethrography. CT is used for monitoring and identifying the extent of the periurethral and periprostatic fluid collections. 

---