[Arterial and neural pedicles of the anorectal region in the human embryo and fetus. Inductor role in normal and pathological development].

To gain a better understanding of the development of ano-rectal malformations, a study of the arterial supply of the ano-rectal region was made in 26 human embryos and fetuses. The development of the ano-rectum was studied in 20 embryos, varying in length from 3 mm to 40 mm (Crown-Rump: 22-60 days), and 6 using Born's method reconstruction; 10 fetuses aged from 3 to 7-8 months were used for a topographic study of the ano-rectal region. 40 fetuses, the majority frozen after expulsion were injected immediately. The fetuses obtained were of ages corresponding to 12-39 weeks of amenorrhea. A staged histologic study after selective micropaque injections of the inferior mesenteric artery was carried out to demonstrate the arterial parietal distribution in the ano-rectum. Smith silver impregnation method, emphasizes the connections between the rectal arteries and extrinsic and intrinsic nerves. The subdivision of the cloaca is constituted by the folding of the ano-rectal and uro-genital parts and by the thickening of the dorsal cloacal epithelium, explained perhaps by the precocious development of arterial supply. The superior rectal artery is predominant and supplies the whole of the anorectum, eventually penetrating the wall of the anal canal. The well-developed median sacral artery is surrounded by a nervous tissue which reaches the M. Levator Ani. The sympathetic nerve fibers follow the arteries until the submucous layer. The development of the intramural plexus of the rectum is independent of the arterial supply.(ABSTRACT TRUNCATED AT 250 WORDS)