41. The Development of the Kidney in Ampullaria (Pila) gigas
- 1The right kidney and left kidney in the embryo arise as evaginations of the pericardium. Mesodermal cells from the neighbourhood adhere to these evaginations.
- 2While the left kidney disappears, the right kidney enlarges and comes into contact with the invagination of the ectoderm which later forms the mantle-cavity in the posterior region.
- 3The right kidney then opens into the mantle-cavity.
- 4That portion of the mantle-cavity with which the kidney comes into contact becomes a tubular organ distinct from the mantle-cavity, and is called the “ureter.”
- 5As a result of torsion, the right kidney of the embryo becomes the left, posterior kidney of the adult.
- 6The ureter becomes dorsal and lies anterior to the left, posterior kidney. It becomes the anterior kidney of the adult.
- 7In the adult the glandular posterior kidney, which opens internally into the pericardium, discharges its products into the anterior kidney, and thence to the exterior.
- 8The anterior kidney of the adult Ampullaría is a modified and enlarged ureter, homologous with the ureter of Vivipara.