Quarterly Journal of Microscopical Science, Vol s2-75, 425-465, Copyright © 1932 by Company of Biologists

Memoirs: The Development of the Amphibian Kidney. The Development of the Kidney of Triton Vulgaris and a Comparison of this Form with Rana Temporaria

¹ Lecturer in Vertebrate Embryology in the Department of Zoology of the University of Edinburgh

1. A description is given of a modified reconstructional technique used in the study of advanced units.

2. It is shown that, in Triton, the definitive kidney is not a derivative of the original mesonephric units, but is of distinct origin.

3. (a) The mesonephros arises from a set of nephroblast vesicles, themselves derived from a solid rod of blastema, extending from the anterior limit of the genital strand to the posterior limit of the coelom.

(b) These nephroblast vesicles develop as shown in Text fig. 2.

(c) The mesonephric units in the posterior region never reach a functional condition and subsequently degenerate.

(d) i. In the region of the developing gonad the mesonephric units develop rapidly to a functional condition.

ii. A basal lateral outgrowth appears near the junction of the developing unit with the archinephric duct.

iii. This outgrowth develops into a blindly ending tubule, which itself gives off other tubules.

4. (a) The primary definitive-kidney units arise from nephroblast vesicles similar to those of the mesonephric units, but present only in the posterior region.

(b) These develop similarly to the mesonephric vesicles (Text-fig. 2) but no basal lateral outgrowths appear.

(c) The detail of the production of the malpighian capsule and peritoneal funnel is given (Text-fig. 3) and the blood-supply discussed (Text-fig. 4).

5. The derived definitive units arise as buds from the anterior and posterior bends of Henle's loop of the primary definitive units (Text-fig. 5).

6. (a) The archinephric duct passes ventro-laterally away from the main mass of the kidney and now forms a ridge in the dorsal peritoneum.

(b) Connective tissue cells migrate into this ridge and form a thick covering to the archinephric duct.

7. (a) In the male the definitive units sever their connexion with the archinephric duct.

(b) Outgrowths appear from a small posterior area of the archinephric ducts; these outgrowths are the ureters.

(c) These ureters grow forward parallel to the archinephric ducts and form connexions with the definitive units.

8. (a) It is explained why the term definitive kidney has been employed in place of opisthonephros.

(b) It is suggested that the extraordinarily rapid growth, and curious production of blind tubules by the sexual units, may be correlated with the possibility of their collecting an endocrine secretion from the developing gonad, which is at this stage without blood vascular irrigation.

(c) It is shown that a precedent for the secondary attachment of the definitive units to outgrowths from the archinephric duct is to be found in Hypogeophis (Brauer, 1902).

9. It is shown that the course of development in both Rana and Triton is fundamentally similar in that both forms--

(a) Develop two sets of units--the early (true mesonephric) units and the later (definitive kidney) units.

(b) The early units play no part in the production of the functional units of the adult.

10. The definitive units of both are also similar if the ‘straight tubules’ of Rana (Gray, 1980) be homologized with the ‘primary definitive units’ of Triton. The differences in the development of the derived definitive units are due to differences in the character of the remaining intermediate mesoderm.

11. It is suggested that the mesonephric glomeruli and peritoneal funnels subserve the additional function of passing something from the coelomic fluid to the blood-stream.

12. If the attachment of the derived definitive units to outgrowths from the archinephric duct found in Gymnophiona is a primitive feature, then an evolutionary series for the amphibian kidney may be shown thus:

(a) All definitive units attached to outgrowths from the archinephric duct (Gymnophiona).

(b) Outgrowths from the archinephric duct in male only (Urodela).

(c) No outgrowths from the archinephric duct (Anura).