Sexual activity and plasma levels of sex steroids in the aspic viper Vipera aspis L. (Reptilia, Viperidae).

Reproductive behavior and associated sexual activity was studied in individual male and female Vipera aspis over a 3-year period in western France in an attempt to correlate mating behavior with blood levels of gonadal sex steroids. Males had higher average levels of both testosterone (T) and 5 alpha-dihydrotestosterone (DHT) than females. Levels of progesterone (P) did not differ significantly between the two sexes but estradiol-17 beta (E2) concentrations were significantly higher in females during the season of mating. Spring mating behavior and copulation in males was associated with significantly increased levels of T and DHT, compared with postmating males; and a similar, but not significant trend, was evident with autumnal mating. The only statistically significant hormonal difference detected in males showing no sexual activity in autumn, was an elevated level of E2 at 0.52 +/- 0.20 ng/ml compared with 0.09 +/- 0.03 ng/ml in spring-breeding males (P = 0.05). Estrus in females is associated with increased levels of all four steroids but significant only for E2 and DHT. Levels of P were significantly reduced in females displaying seasonal anestrous in the spring immediately following reproduction. Females not displaying estrus in either spring or autumn had significantly lower plasma DHT and E2. Although mating behavior in males is associated statistically with elevated levels of T and DHT, a tight correlation is not obvious at the individual level, suggesting that increased concentrations of androgens are a necessary, but not sufficient, condition for mating. The data from V. aspis suggest that, as in a number of other reptilian species, high circulating levels of androgens function to "condition" or "organize" sexual behavior in males which may be displayed at some later time, well after actual levels have fallen, thus engendering the impression that reproductive behavior may be temporally dissociated from essential hormonal stimuli.

Histology of the reproductive tract of hybrids between gonochoristic males and parthenogenetic females of Lepidodactylus lugubris in French Polynesia (Reptilia, Gekkonidae).

Parthenogenetic populations of the gecko Lepidodactylus lugubris are widespread throughout Polynesia. They often occur parapatrically, and occasionally syntopically, with the increasingly rare bisexual populations. In these instances, a small number of hybrid individuals occur and include both "female" and "male" external phenotypes, both with greatly reduced gonads. Histological examination demonstrates that these hybrids possess small ovotestes. The differentiation of the cortical tissue is identical in both "male" and "female" hybrids, but the medullary tissue is more developed in "males." The remainder of the genital tract in "females" resembles that of fertile females in the parthenogenetic and bisexual populations. By contrast, the "male" hybrids are markedly intersexual. In one of the two specimens autopsied, the hemipenes are more or less the same size as those of bisexual males, and the sexual segment of the kidney is hypertrophied and serous. In the other hybrid "male," the hemipenes have a structure similar to that seen in females, and the sexual segment of the kidney is poorly differentiated. In both hybrid "males," the ductus deferens is extremely narrow and further reduced in its middle portion; oviducts are present and resemble those of normal or hybrid females. Thus, embryonic-like gonads are associated with complete and normal female reproductive ducts in hybrid "females." Hybrid "males" also have embryonic-like gonads and feminized genital ducts but associated with secondary sexual characters that match those of sexually active or quiescent normal males.

Patterns of breeding in two species of agamid lizards in the arid subtropical Pilbara region of Western Australia.

The reproductive cycles of two annual species of desert agamids have been studied over a 7-year period in the arid Pilbara region of Western Australia in an effort to identify proximate factors influencing their disparate modes of reproduction. Amphibolurus (= Ctenophorus) nuchalis breeds regularly in spring (September-October in the southern hemisphere) in the southern parts of its range, following reliable winter rainfall which stimulates insect abundance sufficient to sustain their reproductive effort. In the Pilbara region, however, winter rainfall is small and erratic and total rainfall is influenced primarily by summer cyclones. A. nuchalis breeds in spring in the Pilbara in those years when winter rain is substantial, but defers breeding until after the cyclonic rains in late summer in very dry years. The physiological condition of A. nuchalis in spring in such years is depressed, suggesting that resources sufficient to sustain the reproductive effort are lacking, but they show no obvious signs of stress. In years where adequate winter rainfall has been followed by early cyclonic rains, the A. nuchalis population breeds continuously for a 6-month period between October and March of the following year. Although circulating levels of androgens rise significantly in spring in the second species, A. caudicinctus, the gonads remain regressed and this species displays an inflexible pattern of reproduction, breeding only following cyclonic rain in March-April each year, no matter what rains fall in the preceding winter. A. nuchalis thus appears to be an opportunistic vernal breeder, limited only by the availability of resources, whereas A. caudicinctus, which apparently displays the greater reproductive effort of the two species, has a typical aestival pattern of breeding which is uniquely attuned to the enormous burst of productivity occurring in this arid region following the substantial and predictable summer cyclonic rains. Although environmental temperature has often been seen as the primary factor determining reproductive cycles in reptiles, this study suggests that temperature is a necessary but not a sufficient condition for successful reproduction and that the availability of adequate resources may assume an overriding importance, especially in arid habitats where annual rainfall may be highly unpredictable.

Seasonal changes in plasma sex steroid levels in the male tuatara, Sphenodon punctatus, from Stephens Island, New Zealand.

A unique opportunity, occasioned by the sacrifice of five male tuataras (Sphenodon punctatus), was taken to measure the circulating levels of a number of sex steroids, and other parameters, at different seasons throughout the year on Stephens Island, New Zealand. Male tuataras exhibit continuous spermatocytogenesis throughout the year (H. Saint Girons and D. G. Newman, 1987, N.Z.J.Zool. 14,231-237) but levels of sex steroids showed significant seasonal variation nonetheless, with testosterone concentrations being positively correlated with the height of the epithelium lining the epididymal ducts. Plasma testosterone and 5 alpha-dihydrotestosterone levels were highest in February, coincident with the mating season when spermiogenesis is maximal and epididymal ducts are hypertrophied, but DHT concentrations were generally lower and more constant throughout the year. Circulating levels of progesterone, 17 beta-oestradiol, and corticosterone showed no significant changes over the period of sampling which extended from February until August. The tuatara is the only surviving member of the ancient Sub-Order Rhynchocephalia, and it seems likely that testosterone functions as a male sex hormone in this species, as it does in other members of the Class Reptilia.

[Effect of temperature on oxygen consumption of Vipera seoanei Lataste, 1879 (Reptilia, Viperidae) acclimatized to natural conditions]. / Influence de la température sur la consommation d'oxygène de Vipera seoanei Lataste, 1879 (Reptilia, Viperidae) acclimatée à des conditions naturelles.

Relations between respiration rates and temperature for 5 young Vipers previously maintained under natural climatic conditions were analysed from 15 to 30 degrees C. Oxygen consumption increases with temperature and concurrently with a constant Q10, at least for medium consumption, and drops as spontaneous activity is higher.

[Study of Vipera seoanei venom, Lataste, 1879 (Reptilia, Viperidae)]. / Etude du venin de Vipera seoanei Lataste, 1879 (Reptilia, Viperidae).

The venom of Vipera seoanei, species from the north-western Iberic Peninsula and adjacent territories in France, is completely neutralised by different anti-venomous immune sera against European vipers. Its toxicity, sensibly lower than V. berus berus and V. aspis zinnikeri venoms, is close to V. aspis aspis venom.

[Histophysiology of the pars distalis of Tiliqua rugosa (reptilia: scincidae) and the role of the gamma cells (author's transl)]. / Données histophysiologiques sur l'hypophyse de Tiliqua rugosa (Reptilia: scincidae) et notamment la signification fonctionnelle des cellules gamma.

A histological study of the pars distalis of the lizard Tiliqua rugosa following a variety of experimental treatments revealed the presence of only five cell types. Castration or ovariectomy was followed by hypertrophy and degranulation of the beta (B2) cells and, to a lesser degree, the delta cells (B1), and a slight degranulation of the gamma cells (B3), and a net activation of the thyroid gland with a slight hypertrophy of the adrenals. Systemic injections of the enzymatic inhibitor metopirone were followed by a slight involution of the beta cells and a strong hypertrophy and degranulation of the gamma cells as well as hypertrophy of the adrenal tissue. Injections of the synthetic steroid dexamethasone (which suppresses ACTH secretion by a negative feedback on the pituitary) were associated with a slight depression of the activity of the gamma cells and some regression of the adrenal glands. The alpha cells (A2) responded in an irregular manner to the same treatments but they were more often than not degranuled and/or vacuolated when compared with controls. No change in the activity of the X cells (A1) was noted with any of the treatments employed. These results suggest that the gamma cells (B3) which have for long been considered gonadotrophs secreting luteinizing hormone (LH) in reptiles, are in fact corticotrophs, and that there is only one category of gonadotrophs, the beta or B2 cells. Nonetheless, the evident temporal correlation which exists between the secretory activity of the corticotrophs and the gonadotrophs during the sexual cycle in reptiles, suggests that further study of gonad-adrenal inter-relationships should prove profitable in these animals.

[Different types of sexual cycles in male European vipers]. / Les différents types de cycles sexuels des mâles chez les vipères européennes

Sexual cycles in European male vipers can be divided into two types, Spermatocytogenesis occurs in summer, spermiogenesis and mating in spring in three species. Three other species show more or less continuous spermatogenetic activity, but spermiogenesis occurs mostly in late summer and mating in both autumn and spring.

[Influence of temperature on the rate of spermatogenesis, duration of spermatogenic activity and development of secondary sex characteristics in the wall-lizard, Lacerta muralis L. (Reptilia, Lacertidae)]. / Influence de la température sur la vitesse de la spermatogenèse, la durée de l'activité spermatogénétique et l'évolution des caractères sexuels secondaires du lézard des murailles, Lacerta muralis L. (Reptilia, Lacertidae)

A series of experiments was carried out primarily between the 22nd of March and the 27th of June, on 60 Lacerta muralis maintained either under semi-natural conditions in large enclosures or in constant-temperature cabinets maintained at 17.5 degrees C, 20 degrees C, 22.5 degrees C and 27.5 degrees C with a natural photoperiod. Following an injection of tritiated thymidine, the animals were sacrificed at regular intervals and the rate of spermatogenesis was deduced from the progression of the radioactive front in the seminiferous epithelium. The following results were obtained: 1. The rate of spermatogenesis is temperature dependent and increases by a factor of approximately 1.2 per degree centigrade between 17.5 and 27.5 degrees C. The rate is seven times greater at 27.5 degrees C than at 17.5 degrees C. 2. Under semi-natural conditions the interval leptotene-spermatozooid lasts 70 days, slightly less than that found at a constant temperature of 22.5 degrees C. 3. Under semi-natural conditions the rate of spermatogenesis was similar to that in August-September, April-May and May-June which indicates that the lizards were able to maintain their body temperature at an equivalent level by behavioural temperature regulation during the greater part of their activity period. 4. Under semi-natural conditions, or at temperatures in excess of 22 degrees C, spermiogenesis lasts 1.8 times as long as meiosis. 5. At constant temperatures lower than 21 degrees C the development of the cellular lineage is aressted at the young spermatid stage. 6. Constant temperatures between 17.5 and 22.5 degrees C had no effect on the time of involution of the testis at the start of summer. 7. At low constant temperatures, secondary sexual characteristics regress before the usual time: after 4 weeks at 20 degrees C and after 8 weeks at 17.5 degrees C. An expected regression after 8 weeks produced after exposure to a temperature of 22.5 degrees C is probably due to factors other than temperature. 8. In the case of different individuals kept either under natural, semi-natural or experimental conditions, there was no close relationship observed between the time of involution of the seminiferous tubules and regression of secondary sexual characters. ters. 9. These results confirm the concept of endogenous control of sexual regression at the commencement of summer and argue in favour of 2 separate gonadotrophic hormones in reptiles.