Sensory nerve endings in the puborectalis and anal region of the fetus and newborn.
The study was carried out in seven fetuses (ovulation ages were 16, 18, 20, 22, 26, 28, and 31 weeks, respectively) and in five full-term newborn babies. The modified Bielschowsky method and Barker's block silver impregnation were used. It was found that the muscle spindle was arranged in the puborectalis and the external sphincter muscles from the 20th week onward; the tendon organ was located in association with the musculo-tendinous junction of the puborectalis from the 20th week onward; the Pacinian corpuscle lay in the plane of cleavage between the internal anal sphincter and the external anal sphincter from the 22nd week onward, and in the presacral space from the 28th week onward, and the later lagged behind the former in development; the globular endings lay in the presacral space from the 28th week onward; and the free nerve ending was distributed in the epithelium of the anal mucosa and the epidermis around the anus from the 31st week onward. These sensory nerve endings tend to mature gradually with increasing age. It was concluded that these endings may be responsible for the reflex of the external anal sphincter and the anal sensation.
Li
L
L
Department of Pediatric Surgery, Third Affiliated Hospital of China Medical University, Shenyang.
Li
Z
Z
Huo
H S
HS
Wang
H Z
HZ
Wang
L Y
LY
D001003:Anal Canal / Q000196:embryology / Q000294:innervation*; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D009132:Muscles / Q000196:embryology / Q000294:innervation*; D010141:Pacinian Corpuscles / Q000196:embryology; D011631:Pubic Symphysis / Q000196:embryology / Q000294:innervation*; D012007:Rectum / Q000196:embryology / Q000294:innervation*; D011984:Sensory Receptor Cells / Q000033:anatomy & histology*