Seasonal changes in testicular and epididymal histology of the tropical lizard, Tropidurus itambere (Rodrigues, 1987), during its reproductive cycle

Abstract

The reproductive cycles of lizards, including Tropidurus species, have been widely studied. However, few studies describe in detail the ultrastructure and the epithelial changes in the epididymis. Using histology and trasmission electron microscopy, we show the seasonal changes in the testis and epididymis of the lizard Tropidurus itambere, during its annual reproductive cycle. The reproductive cycle of T. itambere was analysed from June 1988 to June 1989 and from June 2001 to June 2002. While the frequency of reproductive males in the population varied throughout the year, there were reproductive males in most months except for February through April. During this nonreproductive period, there is a reduction in the mean seminiferous tubule volume and few sperm were found in both the testis and the epididymis.Keywords: spermatogenesis, reproduction, lizard, ultrastructure, Reptilia. Mudanças sazonais na histologia do testículo e epidídimo do lagarto tropical Tropidurus itambere, durante seu ciclo reprodutivoResumo O ciclo reprodutivo de alguns lagartos já foi extensamente estudado, incluindo algumas espécies do gênero Tropidurus. Entretanto, poucos estudos mostram os aspectos morfológicos do testículo e epidídimo, durante o ciclo reprodutivo anual, e não existe nenhuma descrição ultraestrutural das variações epiteliais no epidídimo. O presente estudo foi feito para mostrar, através da histologia e microscopia eletrônica de transmissão, detalhes das mudanças sazonais no testículo e epidídimo durante o ciclo reprodutivo anual. Acompanhamos o ciclo de Tropidurus itambere, na floresta atlântica brasileira, durante o período de junho de 2001 a junho de 2002. Os machos variam em sua atividade reprodutiva, mas foram considerados potencialmente reprodutivos na maioria dos meses, à exceção dos meses de fevereiro a abril. Durante este período, ocorreu uma redução no volume médio dos túbulos seminíferos e uma menor quantidade de espermatozóides no testículo e no epidídimo.

Proximal Testicular Ducts of the Mediterranean Gecko (Hemidactylus turcicus)

“…Multiple reports on the epididymis typically recognize four different regions of the epididymis, the initial segment, caput, corpus, and cauda (Jones, 1998). However, no regional differences were observed along the length of the epididymis except for a gradual increase in size posteriorly which is similar to that described in Hemidactylus flaviviridis (Haider and Rai, 1981) and Tropidurus itambre (Ferreira et al, 2009; Table 2). The regions of the epididymis described in mammals and in the lizard Sitana ponticeriana are based on the presence or absence of six main cell types.…”

Reproductive Strategies of Brazilian Lizards of the Genus Tropidurus Rodrigues, 1987 (Squamata, Tropiduridae) in the Temporal and Spatial

“…However, important information about the reproductive activity of Neotropical lizards has arisen from studies of members from the family Tropiduridae (sensu Frost et al, 2001). In general, tropidurid lizards present their reproductive cycle in seasonal habitats; and studies on the ecology and reproductive cycles of some species of the genus Tropidurus has currently been studied, including T. etheridgei (Cruz, 1997), T. spinulosus (Cruz et al, 1997), T. semitaeniatus (Vitt & Goldberg;Ribeiro et al, 2010); T. montanus (Van Sluys et al); T. hispidus (Vitt & Goldberg;Vitt et al, 1996), T. oreadicus (Rocha & Bergallo, 1990), T. itambere (Van Sluys;Ferreira et al, 2009) and T. torquatus (Bergallo & Rocha, 1993Giaretta, 1996;Vieira et al;Wiederhecker et al) (see Table III). …”

“…In seasonal environments where climatic conditions are predictable, reproduction tends to occur during some periods (Vitt & Colli, 1994). The reproductive strategies are reflected in the morphology of gonads, allowing the categorization of three types of reproductive cycles: continuous (Wilhoft, 1963;Inger & Greenber, 1966), continuous with variation in reproductive behavior Ruibal et al, 1972), and discontinuous (Marion & Sexton, 1971;Ferreira et al, 2009). Histologically, the continuous cycles are characterized by the presence of all classes of germ cells within seminiferous tubules at different stages of spermatogenesis throughout the year.…”

“…In relation to the tropics, where temperature and photoperiod undergo lower variation, and where drought is comparable to the prolonged cold of temperate zones (Pianka, 1970), the precipitation is apparently the main factor and which most influences the reproductive cycles of lizards Ruibal et al, 1972;Ferreira et al, 2009). The importance of rainfall as a factor regulating the reproductive cycle is expressed both by the higher humidity, essential to prevent desiccation of the eggs, and by the greater availability of food resources (Vallejo & Vallejo, 1981).…”

“…Saita et al 1988;, details of gametogenesis until fertilization of lizards under different climatic and seasonal conditions are scarcely known. The knowledge of reproductive patterns in different environmental conditions lead us to the evaluation of a measurable physiological response as indicator of environmental quality, and provided information to suggest more appropriate methods of management and conservation of biodiversity (Ferreira et al, , 2009.…”