Renal Sexual Segment of the Ground Skink,
Scincella laterale (Reptilia, Squamata, Scincidae).
David
M. Sever1* and William A. Hopkins2
Author Affiliations
1Department of Biological Sciences, Southeastern Louisiana
University, Hammond, Louisiana 70402
2University of Georgia, Savannah River Ecology Laboratory,
Aiken, South Carolina 29803
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, electrondense
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.
Keywords
Reptilia; Squamata; renal sexual segment; histology; ultra structure
**Correspondence to:
David M. Sever, Department of Biological Sciences, Southeastern Louisiana
University, Hammond, LA 70402.
E-mail: dsever@selu.edu.
SREL Reprint #2892
Sever, D.
M. and W. A. Hopkins 2005. Renal sexual segment of the ground skink, Scincella
laterale (reptilia, squamata, scincidae). Journal of Morphology 266:46-59.
