Renal sexual segment of the ground skink, Scincella laterale (Reptilia, Squamata, Scincidae)

Abstract

Mature squamates possess hypertrophied regions of the distal urinary ducts, the renal sexual segment (RSS). The RSS is believed to provide seminal fluid that mixes with sperm and is released into the female cloaca during coitus. This study is the first to describe ultrastructure of the RSS in a lizard collected throughout the active season. The species examined, Scincella laterale, represents the largest family (Scincidae: 1,200 species) of lizards. Although sperm are present in the posterior ductus deferens of male S. laterale throughout the year, an annual spermatogenic cycle occurs that results in spermiation in spring, coinciding with maximum development of the RSS. Female S. laterale may possess stored sperm in vaginal crypts from March-May and large oviductal eggs April-June. Thus, the correlation between mating and RSS activity observed in other squamates is also found in S. laterale. Cytologically, the active RSS consists of columnar cells with numerous apical, electron-dense secretory vacuoles which are released by an apocrine process. The granules stain positively for proteins with bromphenol blue and react with PAS for neutral carbohydrates. After the mating season the RSS undergoes recrudescence and the electron-dense granules are replaced by a mucoid secretion that characterizes more proximal portions of the nephric tubules throughout the year. Little variation in ultrastructure of the RSS occurs between S. laterale and Cnemidophorus lemniscatus (Teiidae), the only other lizard in which seasonal variation of the RSS has been studied using similar methods. Females exhibit differentiation similar to that of males in the distal urinary tubules, but to a lesser degree. This is only the second such report for female squamates, and the differentiation of the region in females is proposed to result from adrenal androgens.

Observations on the Sexual Segment of the Kidney of Snakes with Emphasis on Ultrastructure in the Yellow‐Bellied Sea Snake, Pelamis platurus

“…1D). In lizards in which the Ur is considered part of the SSK, for example, S. lateralis (Sever and Hopkins, 2005), the Ur epithelium is hypertrophied and stains positively for proteins and neutral carbohydrates. The status of this character needs re-evaluation in other scolecophidians.…”

“…Smooth endoplasmic reticulum has been reported in the epithelial cells of the SSK only in Cnemidophorus leminiscatus (Del Conte and Tamayo, 1973) and N. natrix (Kü hnel and Krisch, 1974). SSK tubules have been found in females only in C. leminiscatus and S. lateralis (Sever and Hopkins, 2005).…”

“…The mode of secretion varies, although the most common mode is apocrine. The appearance of the mature secretory vacuoles also is quite variable and may be electron lucent as in B. irregularis (Siegel et al, 2009b); uniformly electron dense as in S. pygaea (Sever et al, 2002), H. turcicus (Rheubert et al, 2011), and P. platurus; biphasic as in C. lemniscatus (Del Conte and Tamayo, 1973), N. natrix (Kü hnel and Krisch, 1974), N. sipedon (Krohmer, 2004), and S. lateralis (Sever and Hopkins, 2005); or consist of both electron lucent and electron dense vacuoles, as in P. taurica (Gabri, 1983) and A. piscivorus (Sever et al, 2008).…”

“…Ultrastructural studies are fewer and limited to Lacerta siccula (Furieri and Lanzavecchia, 1959), Cnemidophorus lemniscatus (Del Conte and Tamayo, 1973), N. natrix (Kü hnel and Krisch, 1974), Podarcis taurica (Gabri, 1983), Seminatrix pygaea (Sever et al, 2002), Nerodia sipedon (Krohmer, 2004), Scincella lateralis (Sever and Hopkins, 2005), Agkistrodon piscivorus (Sever et al, 2008;Siegel et al, 2009a), Boiga irregularis (Siegel et al, 2009b), and Hemidactylus turcicus (Rheubert et al, 2011).…”

Reproductive pattern and sex hormones of Calotes emma Gray 1845 andCalotes versicolor Daudin 1802 (Squamata; Agamidae)

“…However, SSK development in female lizards has been reported in the genus Cnemidophorus (Del Conte, 1972;Del Conte and Tamayo, 1973) and Scincella laterale (Sever and Hopkins, 2005). They suggested that the females had a low level of natural androgens, which caused the SSK development (Del Conte and Tamayo, 1973;Sever and Hopkins, 2005). In the present study, we did not monitor the annual seasonal alterations in female SSK.…”