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Anatomy. — “About the development of the urogenital canal (urethra. 
in man.” By A. J. P. v. p. BroEK. (Communicated by 
Brof. 1. Borg). 
In the following communication I am going to give a deseription 
of the way in which ontogenetically the closure of the urogenital 
canal comes about in man; next I intend trying to throw some 
light upon the composition of this canal from a comparative point 
of view. 
The youngest stage that 1 examined was a male (?) embryo of a 
length of 30 m.m. from crown to coccyx; a stage which is a little 
younger than the oldest female embryo (l.c. Embryo Lo) described 
by Keren *). 
The urodaeum (entodermal cloaca) is divided into rectum and 
sinus urogenitalis; there is a primitive perinaeum. The anal mem- 
brane no longer lies near the surface of the body, but forms 
the bottom of a short proctodaeum. Sinus urogenitalis and proc- 
todaeum combine into a short (200 u) ectodaeum (ectodermal cloaca), 
in whose walls the two component parts are easy-to recognize. If 
we follow the part of the wall proceeding from the sinus urogeni- 
talis, it appears that this at the basis of the penis contributes 
to the limitation of the short genital groove (“Geschlechtsrinne”) ; 
before this it continues in the beginning of the penis as an epithelial 
double lamella, phallusframe (‘Urogenitalplatte”, ‘Urethralplatte”’, 
“lame cloacale” etc.). There is not yet a fossa navicularis. 
In an embryo of 4 cm. the apertures of proctodaeum (anus) and 
sinus urogenitalis are separated by a definitive perinaeum. 
The sinus urogenitalis mouths on the perineal penis-surface with 
an aperture about lozenge-shaped, situated immediately behind a 
circular furrow on the penis. This furrow denotes the limit between 
the glans and the corpus of the penis. 
Following the transverse sections, starting from the apex of the 
penis, it appears how in the part before the navicular aperture 
(fossa navicularis) the phallus-frame as double-lamella penetrates 
into the tissue of the penis (fig. 1 a). In the sphere of the 
fossa navicularis the lamellae of the phallus-frame partly deviate 
(fig. 1.b.), by which on the perineal surface a groove becomes 
visible. The angle between the two leaves becomes gradually larger, 
till at last, in the widest part of the aperture, one is the continua- 
1) Keiser (F.). Zur Entwickelungsgeschichte des menschlichen Urogenitalapparates. 
Archiv f. Anatomie und Physiologie. Anat. Abth. 1896. pag. 55 
