Biology & Sustainability
Spermiogenesis Within the Testicular Tissues of the Spiny Lizard, Sceloporus grammicus
Document Type
Poster Presentation
Location
Indianapolis, IN
Subject Area
Biology & Sustainability
Start Date
11-4-2014 8:30 AM
End Date
11-4-2014 9:30 AM
Sponsor
Kevin Gribbins (Wittenberg University)
Description
Recent studies on squamate sperm morphology have focused on the mature spermatozoon with little attention given to the developmental stages of spermatogenesis. In this study, adult male Sceloporus grammicus testes were analyzed using transmission electron microscopy to investigate the developmental stages of spermiogenesis in comparison with the previously published spermatid maturation in Sceloporus bicnathalis and variabilis to test the hypothesis that sperm development is species specific. Spermiogenesis in S. grammicus follows the same general steps as in all amniotes including acrosome development, nuclear condensation/elongation, and flagellar development. The acrosome forms from Golgi vesicles that merge at the apex of the nucleus similar to other squamate species. The acrosome undergoes differentiation and becomes highly compartmentalized, which is consistent among Squamata. During nuclear condensation and elongation the nucleus condenses in both a spiral and granular fashion, which has also been observed in other squamates. However, early in spermiogenesis, the nucleus has heavier chromatin, more variable nuclear shape, and heavy myelin figures in comparison to other sceloporines. Also unique to sceloporines is the presence of a microtubule band near the developing acrosome in S. grammicus that has been observed in one other lizard, Zootoca vivipara. Overall it appears that spermiogenesis in S. grammicus is similar to that of S. bicanthalis/variabilis with the exception of acrosome complex characteristics. These character differences allow one to speculate that species-specific data can be collected and possibly utilized in phylogenetic analysis. However, at this time too few species within and among taxa have been studied spermatogenically in lizards.
Spermiogenesis Within the Testicular Tissues of the Spiny Lizard, Sceloporus grammicus
Indianapolis, IN
Recent studies on squamate sperm morphology have focused on the mature spermatozoon with little attention given to the developmental stages of spermatogenesis. In this study, adult male Sceloporus grammicus testes were analyzed using transmission electron microscopy to investigate the developmental stages of spermiogenesis in comparison with the previously published spermatid maturation in Sceloporus bicnathalis and variabilis to test the hypothesis that sperm development is species specific. Spermiogenesis in S. grammicus follows the same general steps as in all amniotes including acrosome development, nuclear condensation/elongation, and flagellar development. The acrosome forms from Golgi vesicles that merge at the apex of the nucleus similar to other squamate species. The acrosome undergoes differentiation and becomes highly compartmentalized, which is consistent among Squamata. During nuclear condensation and elongation the nucleus condenses in both a spiral and granular fashion, which has also been observed in other squamates. However, early in spermiogenesis, the nucleus has heavier chromatin, more variable nuclear shape, and heavy myelin figures in comparison to other sceloporines. Also unique to sceloporines is the presence of a microtubule band near the developing acrosome in S. grammicus that has been observed in one other lizard, Zootoca vivipara. Overall it appears that spermiogenesis in S. grammicus is similar to that of S. bicanthalis/variabilis with the exception of acrosome complex characteristics. These character differences allow one to speculate that species-specific data can be collected and possibly utilized in phylogenetic analysis. However, at this time too few species within and among taxa have been studied spermatogenically in lizards.