. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. ANATOMICAL FEATURES SUPRARENAL. Fig. 3. Diagrammatic representations of the urogenital structures in the developing male pig, with special emphasis upon testicular descent. (A) Early relationship of the genital fold (genital ridge), mesonephric kidney and its duct, together with the meta- nephric kidney and the ureter in 20-mm. pig embryo. The relationship of the mesonephric and metanephric ducts to the urogenital sinus is shown. The MiJllerian du
. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. ANATOMICAL FEATURES SUPRARENAL. Fig. 3. Diagrammatic representations of the urogenital structures in the developing male pig, with special emphasis upon testicular descent. (A) Early relationship of the genital fold (genital ridge), mesonephric kidney and its duct, together with the meta- nephric kidney and the ureter in 20-mm. pig embryo. The relationship of the mesonephric and metanephric ducts to the urogenital sinus is shown. The MiJllerian duct is omitted. (B) Male pig embryo about 45-mm., crown-rump length, showing relationship of gonad and metanephric kidney. The metanephric kidney is shown below (dorsal to) the meso- nephric kidney. The gonad (testis) is now a well-defined unit. The portion of the genital fold tissue anterior to the testis becomes the anterior suspensory ligament of the testis, while the genital fold tissue caudal to the testis continues back to join the inguinal liga- ment of the mesonephros (the future gubernaculum). (C) About 80-mm., crown-rump, pig embryo. Observe that the metanephros is now the dominant urinary organ and has grown cephalad, displacing the mesonephric kidney which is regressing and moving caudally with the testis. The remains of the mesonephric kidney at this time are gradually being transformed into epididymal structures. (D) About crown-rump, pig embryo. Observe that the test-is is approaching the internal opening of the inguinal canal. The anterior suspensory ligament is now an elongated structure extending over the latero- ventral aspect of the metanephric kidney; the gubernacular tissue is shown extending downward into the inguinal canal. (E) Later stage in testicular descent. The anterior suspensory ligament of the testis is a prominent structure, while the gubernaculum is compact and shortened. (F) The condition found in the full-term, fetal pig. The testis i
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