Developmental Anatomy and Measurements of the Male Urethra and Related Organs in Human Fetuses

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Two hundred and ninety-eight externally normal human male fetuses in Crown-Rump Length (CRL)from 50 to 345mm (10th-36th week of gestation) were examined by dissection for measurements of the urethra, bladder, prostate gland, and cavernous tissues.The urethral passage was examined by infusion of methylene blue dye, and the state of obstruction was observed by dissection.
It was found that the percent increases in the proximal part to the verumontanum were smaller in relation to CRL than in the distal part. Also in the penile urethra the percent of elongation was smaller than in the fixed portion of the utethra.The bladder was contracted in many specimens, but dilated bladders were not always accompanied by urethral obstruction.In contracted bladders, the muscular layer of the anterior wall
was thinner than the posterior wall in all specimens. The prostate gland had rapidly grown in cross diameter in the fetuses of CRL 190㎜ (6th month) and over.
Three fetuses had an urethral obstruction. The urethral passage was obstructed in 22 cases due to meatal atresia of the glans.
These data provide a standard of measurements for pathologists and clinicians and should assist in making an accurate diagnosis in pediatric urology.