Amphibians employ a genetic mechanism of sex determination, according to all available information on sex chromosomes or breeding tests. Sex reversal allows breeding tests to establish which sex is heterogametic and provides an indication of the mechanism of sex determination. Cases of spontaneous and experimental sex reversal (by temperature, hormones or surgery) are reviewed and illustrated by previously unpublished studies on crested newts. These newts respond conventionally to temperature and hormone treatment but provide anomalous results from breeding tests. It is suggested that both the evolution from temperature dependency to a genetic switch and from ZZ/ZW to XX/XY are superimposed on a generally uniform mechanism of sex determination in all vertebrates.

Triturus cristatus carnifex provides a particularly clear example of sexual dimorphism for chiasma frequency and localisation. Oocytes from normal XX females routinely carry one proximal chiasma on each arm of their lampbrush bivalents. Spermatocytes from normal XY males have more numerous and relatively distal chiasmata. Lampbrush chromosomes from the oocytes of sex-reversed XY neofemales are found to resemble those from normal oocytes in having one proximal chiasma on each bivalent arm. A comparison of particular markers on the heteromorphic long arm of chromosome 1 provides evidence to equate the lampbrush 1A to somatic 1A, and confirms previous reports that lampbrush chromosome 1A is slightly longer than 1B. The XY sex bivalent of neofemales does not show any obvious heteromorphy of recognised marker loops.

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Intrauterine exposure to antiepileptic drugs (AEDs) is associated with neurodevelopmental alterations causing postnatal behavioral and cognitive alterations. These disorders are associated with the interference of these AEDs with the developing cerebral cortex and hippocampal neurons. Therefore, it is crucial to identify the drugs that should be avoided during pregnancy in order to prevent AED mediated developmental alterations. The present study was conducted to investigate the effects of prenatal exposure to the antiepileptic drug gabapentin (GBP) on the rat fetal brain during the organogenesis phase and to examine the potential ameliorative effect of ginger ( Zingiber officinale ). Consequently, the current study addressed the developmental neural changes on the histological, immuno-histochemical and ultrastructural levels. The brain of fetuses from the GBP group showed a highly significant decrease in their weight. Histologically, the cerebral cortex and hippocampus regions of fetuses maternally injected with GBP showed layer disorganization, vacuolated neuropil and massive cell degeneration. The expression of Caspase 3 was significantly increased in the brain of GBP fetuses, unlike the expression of Bcl-2 which was significantly decreased. On the ultrastructure level, the neurons showed pyknotic and chromatolytic nuclei. The cytoplasm was rarefied with swollen organelles. Co-administration of ginger evidently ameliorated most of these effects. In conclusion, GBP administration during pregnancy could possibly affect the developing fetal brain and ginger may have ameliorating effect against the induced GBP neurotoxicity and should be taken in parallel.