|SREL Reprint #1915|
Morphology and Evolutionary Implications of the Annual Cycle of Secretion and Sperm Storage in Spermathecae of the Salamander Ambystoma opacum (Amphibia: Ambystomatidae)
DAVID M. SEVER, JOHN D. KRENZ, KRISTIN M. JOHNSON, AND LISA C. RANIA
ABSTRACT: Females of the marbled salamander, Ambystoma opacum, store sperm in exocrine
glands called spermathecae in the roof of the cloaca. Eggs are fertilized by sperm released from the
spermathecae during oviposition. Some sperm remain in the spermathecae following oviposition, but
these sperm degenerate within a month and none persists more than 6 mo after oviposition. Thus,
sperm storage between successive breeding seasons does not occur. Apical secretary vacuoles are
abundant during the fall mating season and contain a substance that is alcian blue+ at pH 2.5.
Production of secretary vacuoles decreases markedly after oviposition, and the glands are inactive
by the summer months. Ambystoma opacum is a terrestrial breeder, and some mating occurs prior
to arrival at pond basins where oviposition occurs. Mating prior to arrival at the ovipository site may
prolong the breeding season, leading to fitness implications for both males and females. Females
have opportunities for more matings, and the possibilities for sperm competition in the spermathe-
SREL Reprint #1915
Sever, D.M., J.D. Krenz, K.M. Johnson, and L.C. Rania. 1995. Morphology and evolutionary implications of the annual cycle of secretion and sperm storage in spermathecae of the salamander Ambystoma opacum (Amphibia: Ambystomatidae). Journal of Morphology 223:35-46.