THE URINOGENITAL SYSTEM 191 
Fic. 103.—A SERIES OF WHOLLY DIAGRAMMATIC FIGURES TO ILLUSTRATE THE 
Co 
MPARATIVE MORPHOLOGY OF THE URINOGENITAL ORGANS OF THE VERTEBRATA. 
A, The pronephros stage of the Anamnia; B, a later stage of the same ; C, the urinogenital 
apparatus of the male Amphibian; D, the same of the female; E, pronephros 
stage of the Amniota, the mesonephros as yet rudimentary ; F, urinogenital apparatus 
of the Amniota, at a stage at which the sexes are not differentiated ; G, urinogenital 
apparatus of the male Amniota; H, the same of the female; y.n., pronephros ; 
d.pn., duct of the pronephros ; ms., the developing mesonephros ; ms.s., part of 
the mesonephros, becoming converted into the epididymis and parovarium ; 718.¥., 
vestiges of the mesonephros, the paradidymis and the paroophoron ; T, rete and 
vasa efferentia testis ; Tf, a network homologous with these structures at the hilus 
ovarii ; hy.s., stalked hydatid ; ms.7., portion of the mesonephros which in Amphi- 
bians and Selachians becomes the so-called pelvic kidney; d.ms., duct of the 
mesonephros, which in male Amphibians and Selachians becomes (Fig. C) the urino- 
genital, and in females (Fig. D) the urinary duct. In the male Amniota it gives 
rise to the seminal duct (Fig. G), and in the female to the Gartner’s duct (Fig. H). 
v.S., the seminal vesicle, an outgrowth of the duct of the mesonephros; d.m., 
Miillerian duct, which in Mammals becomes differentiated (Fig. H) into the Fallopian 
tube (7i.), the uterus (wt.), and the vagina (vg.); os., its ostium abdominale tube ; 
hy. and u.m. (Fig. G), unstalked hydatids and uterus masculinus (vestiges, in the 
male, of the Miillerian duct, d.m.) ; mt., the definitive kidney or metanephros of the 
Amniota, asserted to arise from the ureter (wr.), itself an outgrowth of the mesonephric 
duct ; al’., allantois (urinary bladder) ; sn., sinus urogenitalis ; p.g., genital pro- 
minence ; g.g., genital glands, undifferentiated stage ; ov., ovary; ¢s., testis; cl., 
cloaca ; a/., hind-gut ; p.a., porus abdominalis ; g.c., Cowper’s glands. 
Tabulated Résumé of the Facts pictorially illustrated on the 
opposite Page. 
Anamnia. Amniota. 
= 
.(|'3 
S| 8 all eget 
= 1c | Develops in all Anamnia, but in’ Still develops in the Amniota, but 
Bas oy all probability never persists as| as an excretory organ undergoes 
a | § a permanent excretory organ. entire degeneration in theembryo. 
iol 
ae 
= 
6 | ¢ | In Elasmobranchii, appears to give | 
4 |'s origin by subdivision to both | Probably persists as the Mesonephric 
5 5 Mesonephric (Wolffian) and Miil- (Wolffian) duct, and contributes 
6 |- lerian ducts. In Amphibia, be-| in some to the formation of the 
a) S comes converted into the Meso-| Miillerianduct. Great differences 
ait phric duct. Its fate in other, of interpretation still exist con- 
oe ie Anamnia is not yet fully investi-| cerning it. 
Z = gated. 
6 | Functions in all Anamnia as a Loses its renal function in all 
a} s urinary gland. In Elasmobranchs,| Amniota (asa rule in the embryo), 
x 5 Amphibians, and one or two and becomes vestigial, except so 
= Fa higher Fishes, its anterior por- far as it becomes an accessory 
2 e tion becomes related to the! portion of the reproductive appar- 
ZN male genital apparatus, the pos-| atus in the male, [and enters into 
oS) ie terior portion persisting as a per-| the formation of the suprarenal 
S manent kidney. body. ] 
