The spermatophore and its structural changes with time in the bursa copulatrix of the silkworm, Bombyx mori

Abstract

The bursa copulatrix of the silkmoth is filled with various secretions and seminal fluid transferred from the male reproductive system during mating. The contents of the bursa include a pearly body, spermatophragma, and spermatophore. The latter consists of a four-layered wall, an inner and outer matrix, and a soft plug. The components of the spermatophore are all heterogeneous, since they are formed by the partially mixed, viscous streams of the male secretions. Apyrene spermatozoa and eupyrene bundles are present only in the inner matrix, but both the matrices are important sites of sperm maturation. After spermatophore formation, the basophilic regions and periodic acid-Schiff (PAS)-granules in both matrices gradually decrease with time. The PAS-granules were identified as glycogen by α-amylase treatment. The inner matrix containing sperm and the outer matrix decrease in volume and become concentrated near the neck of the spermatophore. Apyrene and eupyrene spermatozoa can move toward the ductus seminalis after their maturation. A large, beltlike space which does not stain remains at the periphery of the spermatophore. These structural changes of spermatophore contents seem to reflect metabolic reactions in the spermatophore as the reactor for sperm maturation.

Dynamic digestive physiology of a female reproductive organ in a polyandrous butterfly

“…Although standard accounts of bursal function generally describe it as the site of spermatophore digestion (Engelmann, 1970), researchers have yet to directly quantify the proteolytic capacity of the bursa itself. Rather, studies of spermatophore processing in the silkworm Bombyx mori have suggested that male-donated enzymes are responsible for spermatophore breakdown (Osanai and Kasuga, 1990;Osanai et al, 1987). In contrast, we find that the bursa of P. rapae is extremely proteolytic, achieving levels of digestive activity equivalent to, if not higher than the midgut, which is the region of the larval gut responsible for protein digestion.…”

Two-step acquisition of motility by insect spermatozoa

“…Immotile apyrene spermatozoa have a thick, compact cell membrane, whereas motile spermatozoa have a thin cell membrane with numerous microslits. Motile eupyrene spermatozoa of some lepidopterans were found to have a similar thin cell membrane with microslits 2~ Moreover, the same ultrastructural changes in the cell membrane were observed on treatment of immotile spermatozoa with Arg-C endopeptidase to induce motility ~ 3,19 Polysaccharide is present on the surface of the cell membrane of Bombyx sperm, as in other insects 2, as an extracellular matrix, and forms glycoprotein by binding with the surface protein. Sperm motility probably results from selective degradation of this glycoprotein by an Arg-C endopeptidase, and then deposition of cAMP on the surface of the cell membrane or in the microslits ~ 9…”

Sperm and seminal fluid proteomes of the field cricket Teleogryllus oceanicus: identification of novel proteins transferred to females at mating

“…In insects, sperm are frequently immotile within the male reproductive tract and only activated on delivery to the female. Endopeptidases have been implicated in the triggering of sperm motility in silkworm, Bombyx mori (Osanai et al, 1987a(Osanai et al, , 1987b, the moth Manduca sexta (Friedländer et al, 2001), and in several species of Orthoptera (Osanai & Baccetti, 1993).…”