ABSTRACT
3βHydroxysteroid dehydrogenase activity in the larval gonads of Pleurodeles waltlii (amphibian, urodele); a new histochemical technique for serial sections.
In order to detect a 3β-hydroxysteroid dehydrogenase (3β-HSDH) activity in the larval gonads of the newt Pleurodeles waltlii an original histochemical method has been derived from the cytochemical technique used by Bara & Anderson (1973) in their ultrastructural studies on the same enzyme activity. The new technique which is described here, allows the incubation in toto of the larval gonads, their paraffin embedding and their sectioning into serial sections of 7 /tm thickness. Unisexual, male and female, offsprings were used.
The 3β-HSDH activity could be detected, in the larval gonads, at the level of the inner cells which constitute the medulla inside the cavity of the genital ridge, as early as the end of the first third of the larval life, at a stage when the gonads are not yet differentiated. When an ovary differentiates, the enzyme activity remains at the level of the ovarian sac which will constitute the theca of the follicles in the mature ovary. When a testis differentiates, the medullary positive cells which associate with the germinal cells constitute the testicular ampullae or cysts and (later) become negative; but, at the level of the posterior part of the testis, several clusters of interstitial cells showed a 3β-HSDH activity in metamorphosed and juvenile animals.
The results are discussed in relation with former reports about the steroid-synthesizing cellular sites in the mature ovaries and testes of urodelean amphibians.
