Series D. Sections chosen at intervals from a complete series traversing the peritoneal opening of the Müllerian duct, the remnant of the head-kidney, and the termination of the Müllerian duct. Zeiss C, ocul. 3 (reduced one-third).
Nos. 1 and 2. Sections through the persistent anterior opening of the head-kidney (abdominal opening of Müllerian duct). The approach of the Wolffian duct to the groove may be seen by a comparison of these two figures. In the sections in front of these (not figured) the two are much more widely separated than in No. 1.
No. 3. Section through the Müllerian duct, just posterior to the persistent opening.
Nos. 4 and 5. Remains of the ridges, which at an earlier stage connected the first and second grooves, are seen passing from the Müllerian duct to the peritoneal epithelium.
No. 6. Rudiment of the second groove (gr2.) of the head-kidney.
Between 6 and 7 is a considerable interval.
No. 7. All traces of this groove (gr2.) have vanished, and the Müllerian duct is quite disconnected from the epithelium.
No. 8. Rudiment of the third groove (gr3.).
No. 9. Müllerian duct quite free in the space between the peritoneal epithelium and the Wolffian duct, in which condition it extends until near its termination. Between Nos. 9 and 10 is an interval of eight sections.
No. 10. The penultimate section, in which the Müllerian duct is seen. A lumen cannot be clearly made out.