DEVELOPMENT OF THE PELVIC PLEXUS IN HUMAN EMBRYOS AND FETUSES AND ITSRELATIONSHIP WITH THE PELVIC VISCERA

Development of the pelvic plexus is studied in 15 human embryos and 2 fetuses ranging in size from 4 to 132 mm. C.R. length. A tridimensiona l reconstruction of the entire pelvic block was made in two specimens (30 and 132 mm. C.R. length) 80 X. The first ganglionic elements appea r in Carnegie's stage 16, but the real definition of what in the final anatomy of the plexus is described as the hypogastric ganglion (Lee-F rankenhauser) is formed in stage 18. Complete development of the plexu s occurs in stage 23. Other relevant facts are: the appearance in stag e 18 of the pelvic splanchnic nerves, which are formed from S2, S3 and S4, the involvement of S1 and S5 were not observed in any case. In al l specimens studied, a close proximity was seen between the pelvic ple xus and genitourinary organs. Starting in stage 18, the terminal urete r consistently crosses the posterosuperior part of the pelvic plexus.