Comparative biology of sperm storage in female salamanders

Abstract

Females in seven of the ten families of salamanders possess cloacal glands called spermathecae that store sperm. The annual cycle of sperm storage has been studied by light and electron microscopy in eight species representing five families. In these taxa, we recognized 14 characters associated with the spermathecae and traced their evolution on a phylogeny of salamanders based upon other characters. The plasticity and phyletic significance of the spermathecal characters varied greatly. Plethodontids have complex spermathecae while other families possess simple spermathecae; thus, this character has phyletic value as well as being highly conserved within the Salamandroidea. Other characters, such as carbohydrate histochemistry, are highly plastic and show no obvious phyletic trends. The significance of some of these variable characters, such as duration of sperm storage, is apparent only after including in the analysis other aspects of the reproductive cycle, such as length of the mating season. Additional comparative studies, employing the protocol used in this paper, will help further clarify the relationships between phyletic and functional variability in sperm storage mechanisms in salamanders.

Sperm storage in females of the smooth newt (Triturus v. vulgaris L.): II. Ultrastructure of the spermathecae after the breeding season

“…Perhaps ultimately these sperm will reach the epithelium and become phagocytized, or perhaps they will degrade in the lumen (Sever and Brizzi 1998), or simply leak out of the spermathecae, as noted for unused sperm in the vas deferens of the salamander Ambystoma macrodactylum columbianum (Zalisko and Larsen 1989). Perhaps ultimately these sperm will reach the epithelium and become phagocytized, or perhaps they will degrade in the lumen (Sever and Brizzi 1998), or simply leak out of the spermathecae, as noted for unused sperm in the vas deferens of the salamander Ambystoma macrodactylum columbianum (Zalisko and Larsen 1989).…”

“…Perhaps ultimately these sperm will reach the epithelium and become phagocytized, or perhaps they will degrade in the lumen (Sever and Brizzi 1998), or simply leak out of the spermathecae, as noted for unused sperm in the vas deferens of the salamander Ambystoma macrodactylum columbianum (Zalisko and Larsen 1989). Sever and Brizzi (1998) urge caution in accepting reports of long-term effective sperm storage (>6 months) in the spermathecae of salamanders. 1999).…”

“…1995) and Notophthalmus viridescens (Sever et al . Joly (1960) proposed that sperm embedded in the spermathecal epithelium of Salamandra salamandra could be receiving nourishment, but others consider this unlikely (Sever and Kloepfer 1993;Sever and Brizzi 1998;Sever and Hamlett 1998). In other species in which spermathecal ultrastructure has been studied, no evidence of spermiophagy by the epithelium has been found, i.e.…”

“…1996b). Eventual sperm degeneration in the lumen, however, has been reported in all species in which ultrastructure has been used to study the annual cycle of sperm storage in salamanders (Sever and Brizzi 1998). A. tigrinum (Sever 1995); Amphiuma tridactylum (Sever et al .…”

“…Females in the seven families of salamanders that constitute the suborder Salamandroidea possess sperm storage glands, spermathecae, in the walls of their cloacae (summarized by Sever 1991;Sever and Brizzi 1998). In the cosmopolitan family Salamandridae, spermathecae have been described at the light microscopy level for 22 of the 53 species (Sever 1992a) including Triturus vulgaris , the most widespread and abundant species of urodele in Europe (Griffiths 1996).…”