Morphology and Ultrastructure of the Pronephros of Testudo hermanni Gmelin, 1789 (Chelonian Reptiles)

Abstract

The aim of this study was to investigate the morphology and ultrastructure of the pronephros of Testudo hermanni as observed in the earlier part of its development. This paired structure appears during renal ontogenesis and originates from the first somites localised in the cephalic part of the embryo. The first pronephric evidence is noted at stage 12. The kidney is composed of large glomeruli that are devoid of a capsule and protrude into the coelomic cavity. A ciliated nephrostome provides access to short renal tubules, lined with a well-developed brush border. Two nephric ducts on the lateral sides of the embryo are connected to the tubules. The cytological characteristics of the pronephric structure suggest that it might be functional, at least in the first part of development. The pronephros of Testudo hermanni regresses after a short time around stage 18, while the mesonephros is already well differentiated. Its plesiomorphic characteristics, similar to those observed in amphibians, might be related to the phyletic position of chelonians within the reptiles.

Differentiation of Steroidogenic Cells in the Developing Adrenal Gland ofTestudo hermanniGmelin, 1789 (Chelonian Reptiles)

“…The relation between the interrenal tissue and the kidneys during development was absent in the early period in which a pronephric kidney was present only at the cephalic end of the embryo (Chimenti and Accordi, ); in the intermediate and advanced period, the gland was in contact with the mesonephros and metanephros, the first lying in a ventral position and remaining functional until hatching; conversely, the metanephros laid in a dorsal position and increased in size during organogenesis.…”

“…A total of 30 eggs were collected from pairs of common turtle, Testudo hermanni, reared for authorized scientific purposes. As reported in a previous work (Chimenti and Accordi, ), eggs were maintained at a steady temperature of 34°C in an incubator. All eggs were individually numbered and placed in plastic boxes (4.5 × 15 × 23 cm) containing a 1:1 mixture by weight of granular vermiculite and distilled water.…”

“…It is therefore peculiar among reptiles, resembling in shape to that of amphibians, being organized as a stripe on the ventral renal surface. This different position seems to be due to the persistence of the mesonephros during the early period after hatching (Chimenti and Accordi, ).…”

“…As regards, the development of the gland within the family Testudinidae, the chromaffin cells were described previously (Accordi et al., ), and the relation between the chromaffin cells and the kidney was also known (Chimenti and Accordi, ). The literature review indicated that informations about ultrastructure of the embryonic and adult interrenal cells in chelonian species are still lacking.…”

Pronephros and mesonephros characterization during the embryonic development of the giant South American river turtle, Podocnemis expansa (Podocnemididae: Testudines)

“…In males, the mesonephros ducts differentiate into the efferent ducts while degenerating completely in females (Georgas et al, 2011). The metanephros arises from the ureteric bud, growing in the posterior portion of the nephric ridge and gradually replacing the mesonephros, becoming the adult amniote kidney (Chimenti & Accordi, 2011; Ewert, 1985; Fox, 1977; Romer, 1978).…”