Fetal development of striated and smooth muscle sphincters of the male urethra from a common primordium and modifications due to the development of the prostate: an anatomic and histologic study.
BACKGROUND
The aim of the study was to investigate the development of the human urethral sphincter complex during fetal development.


METHODS
23 human male fetal specimens were investigated. The histological sections were processed according to the epoxy resin-based plastination technology.


RESULTS
At 9th week of gestation, a combined sphincteric primordium of the rhabdosphincter and the lissosphincter is situated at the anterior and lateral aspects of the membranous and prostatic urethra. Both muscular components assume an omega-shaped configuration due to the presence of a constant connective tissue raphe posterior to the urethra that anchors the rhabdosphincter in the perineal body. Development of the prostate laterally and posteriorly does not modify the growth of the urethral sphincter complex anteriorly but inhibits its development laterally and posteriorly.


CONCLUSIONS
The important morphological characteristics of the male adult rhabdosphincter and lissosphincter can be seen very early in fetal development.
Sebe
Philippe
P
Department of Urology, Tenon Hospital, Paris, France. philippe.sebe@tnn.ap-hop-paris.fr
Schwentner
Christian
C
Oswald
Josef
J
Radmayr
Christian
C
Bartsch
Georg
G
Fritsch
Helga
H
D047109:Fetal Development; D006801:Humans; D008297:Male; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000196:embryology*; D009130:Muscle, Smooth / Q000196:embryology*; D011467:Prostate / Q000196:embryology*; D014521:Urethra / Q000196:embryology*