Spermathecal Epithelium Research Articles

Sperm storage organs change with female age and mating history in the Golden Silk spider Trichonephila clavipes (Araneae: Araneidae)

AbstractFemale sperm storage organs in arthropods are used as taxonomic characters since it is assumed that they do not change after maturation. However, in the Golden Silk spider, Trichonephila clavipes, the shape and sclerotization of the spermathecae change with a mating event. Moreover, mating in T. clavipes consists of several hundred copulations, but the male transfers all sperm during the first insertion of each pedipalp. Given this puzzling mating behaviour, we hypothesize that multiple copulations serve purposes other than sperm transfer and uptake, such as further altering the morphology of the storage site and/or transferring substances other than sperm. We compared virgin female T. clavipes with females after two copulations, one for each spermatheca, and after ad‐libitum mating. Each treatment consisted of two sub‐treatments in which the state of the sperm storage organs was inspected after a short (1–3 days) or a long (11 days) time interval after the female's final moult. The size of the spermathecae increased twofold in all mating treatments compared to virgin females. The thickness of the spermathecal wall increased significantly with time in all treatments similarly. The spermathecal epithelium, which releases secretion into the lumen of the spermathecae, seems most active in virgin females during the time when mating would normally occur and turns less active after mating and with age. The spermathecae contain secretion produced by the female before mating; and after mating, sperm and another secretion transferred by the male. The numerous sperm‐less matings in the ad‐libitum treatment resulted in male secretion in the copulatory ducts of the female genitalia, likely impeding sperm transfer by subsequent males. Out study shows that female genitalia can change considerably after having reached maturity and suggests that sperm‐less matings evolved in the context of sperm competition.

Mating mediates morphophysiological changes in the spermathecae of Coptotermes gestroi queens

AbstractInsect spermathecae play a crucial role in sperm storage and maintenance prior to egg fertilization. Within eusocial insects, this structure is well studied in the Hymenoptera, whose queens copulate during a short period early in life and store sperm for up to decades. Within Isoptera, sperm storage and maintenance inside the spermatheca are poorly understood, especially due to the presence of a sperm‐providing king. Here, we compared the morphometric and morphophysiological features of the spermathecae of virgin and mated queens of the invasive termite Coptotermes gestroi (Wasmann) (Isoptera: Rhinotermitidae). The spermatheca comprises a finger‐shaped reservoir divided into two regions and a duct limited by a narrow transition. The superficial spermatheca area, as well as the luminal area, increase significantly after insemination, even among queens whose reproductive activity was reduced, suggesting that sperm storage continues during such conditions. The secretion of proteins and polysaccharides into the spermathecal lumen was a remarkable feature for both virgin and 4‐year‐old queens, although the concentration of the secreted content increased in the latter group. It suggests that spermatheca activation occurs before pairing, but its secretory activity intensifies to nourish and provide energy for the stored spermatozoa. Ultrastructure of the spermathecal epithelium showed a bicellular unit, composed of a secretory cell and associated canal cells. Secretory vesicles of various electron densities were observed next to the receiving canal of the secretory cells in both virgin and 2‐year‐old queens. Nevertheless, strongly electron‐dense vesicles were only recorded for mated queens, which were associated with the increasing synthesis of proteins. The occurrence of rough endoplasmic reticulum and richness of mitochondria reinforces the protein synthesis and transport of contents towards the spermathecal lumen. In conclusion, the spermatheca of C. gestroi undergoes morphometric and physiological changes after mating, and further analysis may provide insights into the chemical nature of the spermathecal secretion prior to and after this event.

Über die Ablagerung von Amyloid im Samenblasenepithel der Bienenkönigin (Apis mellifica L.♀)

Summary The cytoplasm of the spermathecal epithelium of the queen honeybee shows already quite early particular hyaline corpuscles, that grow with progressing age very quickly in number and size. By means of histochemical reactions could be profed that these formations consist of amyloid. This amyloid degeneration of the spermathecal epithelium - disclosed for the first time at an insect - may possibly be of essential importance for the premature and due to age drone-laying of mated queens.

The ultrastructure of the spermathecae in the Collembola Symphypleona (Hexapoda)

The fine structure of the paired spermathecae of two Symphypleona Collembola, Sminthurus viridis and Allacma fusca, was studied. The spermathecal epithelium is rich in pigment granules, while secretory organelles are scarce, consisting of a few mitochondria and microtubules, scattered cisterns of endoplasmic reticulum and Golgi systems. Small isolated secretory granules are visible in the apical cell region, where irregular microvilli are present. Beneath the epithelium, large cells rich in endoplasmic reticulum and Golgi systems are present; they are separated from the epithelial cells by a thin basal lamina. The epithelium is lined by a thin cuticle, which forms thin extensions at the beginning of the spermathecal duct. At this level, muscle fibers are visible. The spermathecal lumen is filled with many spermatozoa. At molting, the spermathecal epithelial cells detach from the cuticle and a large electron-transparent space is evident between the cytoplasm and the cuticle. The cytoplasm has few pigment granules and the spermathecal lumen contains degenerating spermatozoa. After 3 days, the spermathecal epithelium regains its usual appearance and the spermathecal lumen is empty. The two species of Collembola Symphypleona do not have accessory glands. Compared with the Arthropleona Orchesella villosa, which has a single spermatheca and two accessory glands (Dallai et al. 2008 J Morphol 269:464-478), a great difference has occurred in the organization of the female genital system of these species. The results are discussed in light of the implications for reproductive behavior and egg protection in Symphypleona.

Sperm aggregations in the spermatheca of the red back salamander (Plethodon cinereus)

AbstractThe spermatheca of Plethodon cinereus is a compound tubular gland that stores sperm from mating in early spring (March–April) to oviposition in summer (June–July). The seasonal variation of sperm storage in this species has previously been studied by light and transmission electron microscopy. In this paper, sperm aggregations, interaction of sperm with the spermathecal epithelium, and spermathecal secretions are studied using scanning electron microscopy. Within spermathecal tubules, relatively small groups of sperm are aligned along their entire lengths in parallel arrays. This pattern is similar to other plethdontids with complex spermathecae. Lumina of spermathecal tubules are filled with secretory material in April prior to the arrival of sperm, and after sperm appear, a coating of secretory material persists on the apices of the spermathecal epithelium. Sperm peripheral to the central luminal mass can become embedded in the secretory matrix or pushed deeper into the spermathecal epithelium. The spermathecal secretions may serve to attract and prolong the viability of sperm, but sperm that become enmeshed in the secretions or epithelium are phagocytized. Sperm and spermathecal secretions are largely absent after ovulation and in summer months, and new secretory vacuoles are formed in fall, although mating does not occur until spring.

Differentiation of the reproductive tract between dominant and subordinate workers in the Japanese queenless ant Diacamma sp.

AbstractIn queenless ants, gamergates (mated egg‐laying workers) fulfil the reproductive task normally reserved for the queen. Every worker is a potential gamergate, thus we expect pronounced conflicts over sexual reproduction within their colonies. In the queenless ant genus Diacamma, gamergates inhibit nest mates from mating by aggressively removing (‘mutilating’) a pair of small appendages on the thorax, termed gemmae, shortly after eclosion. Dissection and serial sectioning of the reproductive tracts of both mutilated and unmutilated individuals of Diacamma sp. from Japan at different ages revealed that mutilation inhibits the development of the bursa copulatrix and the spermatheca, two structures fundamental for sexual reproduction. The precursor of the bursa copulatrix develops into a fully functional structure in unmutilated individuals, whereas it degenerates irreversibly in mutilated callows. Experimental manipulations showed that the removal of the gemmae is not the sole factor regulating this development. The spermathecal epithelium and accessory spermathecal gland of unmutilated individuals are thicker than that of mutilated individuals, indicating a higher degree of activity in the former. Mutilated females are therefore left incapable of copulating and less competent for long‐time sperm storage.

Genital structures in the entelegyne widow spider Latrodectus revivensis (Arachnida; Araneae; Theridiidae) indicate a low ability for cryptic female choice by sperm manipulation

The female genital structures of the entelegyne spider Latrodectus revivensis are described using semithin sections and scanning electron microscopy. Apart from the tactile hairs overhanging the opening of the atrium, the contact zones of the female epigynum are devoid of any sensilla, indicating that the female does not discriminate in favor or against males due to their genital size or stimulation through copulatory courtship. The dumb-bell shape and the spatial separation of the entrance and the exit of the paired spermathecae suggest that they are functionally of the conduit type. Not described for other entelegyne spiders so far, the small fertilization ducts originating from the spermathecae of each side lead to a common fertilization duct that connects the spermathecae to the uterus externus. During oviposition, it is most likely that spermatozoa are indiscriminately sucked out of the spermathecal lumina by the low pressure produced by the contraction of the muscle extending from the epigynal plate to the common fertilization duct. As no greater amounts of secretion are produced by the female during oviposition, and no activated sperm are present within the female genital tract, the secretion produced by the spermathecal epithelium does not serve in displacement or (selective) activation of spermatozoa. These findings suggest that female L. revivensis are not able to exert cryptic female choice by selectively choosing spermatozoa of certain males.

Pathways and destination of some male gland secretions in female Locusta migratoria migratorioides (R&F) after insemination.

The white secretions (WS) from the tubules of the male accessory glands (AG) of Locusta migratoria are composed of peptides and proteins. The WS are transferred during mating to the female's spermatheca. They have been followed to their destinations with immunological and radioactive marker techniques. In the spermatheca, peptides are split off from WS-protein complexes, permeate the spermathecal epithelium via glandular cells, enter the hemolymph and attach to other proteins in various target organs such as the dorsal fat body, the preterminal/terminal oocytes, and the follicular cells. In developing eggs, they concentrate at the posterior pole where sperm enters the egg, and in early embryogenesis they are found in the germ band. These results extend the functions of the spermatheca and the role of the male during the reproductive process.

Development of the sperm storage organ in Arianta arbustorum (Stylommatophora: Helicidae).

In promiscuous species, multiple sites of sperm storage are considered to be an adaptation of females for post-copulatory control over sperm storage and selection to control offspring paternity. 1,2 In the stylommatophoran gastropod Arianta arbustorum (Linnaeus), the sperm-storing spermatheca consists of two to nine blind tubules: a main tubule and one to eight lateral tubules. 3,4 The considerable variability in paternity patterns of double-mated individuals and the observation that incoming sperm are not equally distributed among spermathecal tubules, i.e. some are filled and others remain empty, suggest that A. arbustorum may store and use sperm from different mating partners selectively. 3,5 In addition, ultrastructural analyses of the spermathecal epithelium with its ciliation and of the musculature surrounding the spermatheca indicate that anatomical correlates necessary for sperm manipulation exist. 6,7 The sperm storage sites themselves may be subject to sexual selection, provided that there is heritable variability of those structures, which are important for exercising cryptic female choice. 8,9 In a previous study, we investigated whether different risks of sperm competition, which we expected in populations with different densities, would affect spermathecal morphology. There may be several reasons why we did not detect any density dependence including lack of heritability. 4,10 Instead, the number of spermathecal tubules might depend on an individual’s age or state of sexual maturity. The ontogeny of a complex spermatheca such as that of A. arbustorum has not been investigated in much detail so far. It has only been observed 11 that in A. arbustorum the fertilization pouch (sensu 3 ), of which the spermatheca is one part, develops at an age of about 6 weeks. However, the development of the structures of the fertilization pouch including the spermatheca was not studied so far. In the present paper we investigate the development of the spermatheca in A. arbustorum. We were particularly interested in whether the number of spermathecal tubules increases with age/size (see below) or whether the anlage of all spermathecal tubules is formed during an early stage of ontogenesis. The latter would be an indication that the complexity of the spermatheca is mainly genetically controlled and, thus, heritable. A. arbustorum is common throughout Europe from the Pyrenees to the Ukraine reaching northwards as far as Scandinavia. The species occurs from the lowland up to 3000 m a.s.l. 12,13 The snail has determinate growth indicated by a reflected and thickened lip. Formation of the lip and sexual maturity roughly coincide at an age of 2‐4 years, and adults live another 3‐4 years. 14 A. arbustorum mates repeatedly during the

Female sperm storage in amphibians.

The three orders of extant amphibians are Gymnophiona, Anura, and Urodela. Although all gymnophionans apparently have internal fertilization and many are viviparous, female sperm storage is unknown. Internal fertilization has convergently evolved in a few anurans, but females of just one species, Ascaphus truei, are known to possess oviductal sperm storage tubules (SSTs). The SSTs of A. truei are similar anatomically to such glands in squamate reptiles. This similarity is convergence due to similar functional adaptations and/or internal design constraints. In salamanders and newts (Urodela), absence of sperm storage in females is the ancestral condition (three families). In the derived condition, sperm storage occurs in cloacal glands called spermathecae, and their possession is a synapomorphy for females in the suborder Salamandroidea (seven families). Salamandroids are the only vertebrates with cloacal sperm storage glands. In this paper, a phenetic analysis of variation in spermathecal characters reveals patterns of convergence in certain spermathecal characters in unrelated taxa that breed in similar habitats. In the family Salamandridae, a role in sperm nutrition for the spermathecal epithelium is questioned, and the widespread occurrence of spermiophagy is related to other reproductive strategies. I propose how the packaging of sperm in structurally different types of spermathecae may influence male paternity.

The spermatheca in the land snail, Arianta arbustorum (Pulmonata: Stylommatophora): muscle system and potential role in sexual selection

Abstract. Previous studies have shown variable patterns of paternity after multiple mating, and also variation in sperm storage among individuals of Arianta arbustorum, which suggests that the spermatheca may influence paternity in this promiscuous land snail. To identify possible morphological correlates of sperm manipulation, we investigated arrangement and ultrastructure of the muscles of the spermatheca. The musculature surrounding the 2–9 spermathecal tubules is arranged in a complex three dimensional network. In addition, each tubule has a thin sheath in which longitudinally oriented cells make up the innermost layer. Usually, the smooth muscle cells are enclosed by connective tissue. Only occasionally is direct muscle‐muscle contact established through dense plaques. The short thick filaments, their small diameter, the relatively weak development of the tubular system and sarcoplasmic reticulum, and the low density of mitochondria indicate that the muscle cells contract relatively fast but with little strength, that they recover slowly, and have low endurance. A single muscle cell may be innervated by several axons and one axon may contact several muscle cells. Combining evidence of the present paper and a foregoing investigation on the spermathecal epithelium, we suggest that the main function of the spermathecal muscles is to expel sperm stored for fertilization, while the ciliation of the common duct is probably responsible for the distribution of sperm among the tubules.

The spermathecal epithelium, sperm and their interactions in the hermaphroditic land snail Arianta arbustorum (Pulmonata, Stylommatophora)

Previous investigations showed that in Arianta arbustorum incoming sperm are not equally distributed among all tubules of the sperm storage organ, the spermatheca, and it has been assumed that the sperm recipient might influence paternity after multiple mating. Understanding postmating sexual selection requires understanding the function of the genitalia. Against this background we analyse the ultrastructure of the spermathecal epithelium, give a brief description of the sperm morphology and describe the sperm–epithelium interactions. The epithelium of the spermatheca, which consists of up to nine blind tubules originating from a common duct, is a monolayer composed of a single cell type. Only the density of the ciliation increases along the tubules and the common duct. In addition, the cilia of the latter are more than 50% longer than those in the tubules. These long and densely arranged cilia not only prevent autosperm from getting into the spermatheca, but may also be responsible for sorting sperm in the spermatheca allowing the recipient to store sperm from different partners separately. The most peculiar characteristics of the epithelium are the wide intercellular spaces at the base continuing apically into narrow channels used for extracellular transport. Below apical junctions, the cells adhere to each other through interdigitations, which form an extensive labyrinth at the base and rest on the basement membrane. Rough endoplasmic reticulum and Golgi complexes are mainly found in the vicinity of the basally positioned nucleus. A large vacuole lies above the nucleus and the apical portion of the cytoplasm is densely populated with mitochondria. Vesicles of various sizes are also found mainly in the apical region. The spermatozoa stored in the hermaphrodite duct prior to transfer are characterised by an acrosome forming an angle of 90° with the longitudinal axis of the nucleus and vesicles of undefined shape in the terminal end of the flagellum. In the spermatheca the spermatozoa lose their perinuclear sheath and the acrosome is almost in line with the longitudinal axis of the sperm. This process is interpreted as capacitation. In the spermatheca, the capacitated spermatozoa are in close contact with the epithelial cells. However, an exchange of substances was not observed. It is assumed that the epithelium provides the environment for sperm quiescence rather than nutritives.

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

AbstractSperm storage in cloacal spermathecae was studied in females of Triturus v. vulgaris from southern England killed at the end of the breeding season in June. This species mates and oviposits eggs in ponds from March to June. Included in the sample were 12 unmated females collected in terrestrial situations in March and mated in the laboratory. Some of these females oviposited viable eggs in the laboratory whereas others did not oviposit after mating. In addition, we examined five females with unknown mating histories that were collected from a breeding pond in June. We found that all of the specimens contained some stored sperm and were similar in spermathecal ultrastructure. The spermathecae exhibited characteristics of secretory epithelium at the end of a cycle, including irregular heterochromatic nuclei surrounded by scant cytoplasm, absence of organelles involved in synthetic activities, few secretory vacuoles, and wide intercellular canaliculi. Spermiophagy by the spermathecal epithelium was extensive. In contrast, spermathecae from females at the beginning of the breeding season as reported in our previous study were actively producing a PAS+ secretion and did not exhibit spermiophagy. Spermiophagy is a means of eliminating sperm prior to the next breeding season.

Ultrastructural and functional aspects of the spermatheca of the African Migratory Locust Locusta migratoria migratorioides (Reiche and Fairmaire) (Orthoptera: Acrididae)

The ultrastructure of the spermathecal epithelium of the African Migratory Locust Locusta migratoria migratorioides R. & F. (Orthoptera: Acrididae) was investigated with the aid of transmission and scanning electron microscopic methods. The unpaired spermatheca can be subdivided into a multiple coiled tube and a terminal bulb region with vestibule, small apical and extensive pre-apical diverticulum. The wall of the spermatheca consists of a chitin intima, a layer of epithelial cells with a distinct apical microvilli border and a layer of gland cells, whereby slender projections of the epithelial cells extend between the gland cells. Through extensive folding, the basal plasma membrane of the gland and epithelial cells form a huge labyrinth, which is bounded by a basal lamina. Extending into the above mentioned projections there are bundles of parallel-arrayed microtubules, which run perpendicular to the microvilli border of the epithelial cell. They end in the base region of the microvilli and in the basal labyrinth on hemidesmosomes and serve to provide a mechanically stressable anchorage for the epithelium. The gland cells show structures typical for the production of export proteins: ribosomes, rER, dictyosomes, as well as vesicles of different size and electron-density. Every gland cell contains an extracellular cavity, arising through invagination, which is coated with a microvilli border. Over an end-apparatus and a ductule joining onto it (also with chitin intima) the lumen of the extracellular cavity is connected with the spermathecal lumen. The release of secretions and other substances from the epithelium into the spermatheca lumen is as possible as the uptake of substances from the latter into the epithelium. Regional differences in the fine structure of the cuticular intima, epithelial and gland cells point to different functions of the epithelium in these regions.

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

Sperm storage in cloacal spermathecae was studied in females of Triturus v. vulgaris collected early in the breeding season in southern England. Females collected in terrestrial situations, presumably unmated, were mated in the laboratory, and the ultrastructure of the transferred sperm and the spermathecae was observed at various intervals after mating. Sperm from a spermatophore cap lodged in a female's cloacal orifice can migrate into spermathecae within 1 hr after mating. Spherical structures on the axial fibers of some sperm in the cap could indicate immaturity. Disorderly clusters of sperm from the cap are still present in the cloacal chamber 12 hr after mating but are absent 24 hr after mating. During storage, sperm often are in tangled masses in the spermathecal tubules. The sperm are coated with spermathecal secretions, and some sperm nuclei were observed embedded in the spermathecal epithelium. Little evidence for spermiophagy early in the breeding season was found. During oviposition, mazes of sperm occur external to the spermathecal orifices, and sperm may be released in this condition onto eggs as they pass through the cloaca. The tangled clusters in which sperm are found from pick-up to oviposition are hypothesized as an adaptation to reduce the effectiveness of sperm competition from the ejaculates of rival males. Additional studies, using the same protocol and covering the entire cycle of sperm storage, are necessary to enable interspecific comparisons leading to phylogenetic hypotheses.

Morphology of the spermatheca, oviduct, intermediate chamber, and vagina of the adult snow crab (Chionoecetes opilio)

The morphology of the reproductive tract of the adult female snow crab (Chionoecetes opilio) at different stages of reproductive life was examined within the framework of studies on sperm competition. Apart from an ovary and oviduct, the tract consists of an epithelium-lined spermatheca and a cuticle-lined intermediate chamber and vagina. The morphological traits of these components are markedly influenced by the degree of spermathecal loading. Several amendments to previous descriptions are necessary: (i) pouches are not a permanent feature of the spermatheca; (ii) the outer part of the spermatheca wall is a true capsule that overlies a multilayered epithelium divided into anchoring, proliferative, and secretory strata; (iii) spermathecal secretions are of the merocrine type; and (iv) the epithelium of the spermatheca is not pigmented. Tridimensional analysis revealed that the vagina connects to the intermediate chamber via a parietal opening. The intermediate chamber is a flexible structure circled dorsally by 3-5 cuticular folds that project into its lumen. The oviduct crosses the thicker terminal segment of the spermathecal epithelium with a dorsoventral incidence, to a point opposite the parietal opening of the vagina, in such a way that it delivers its contents almost directly into the intermediate chamber. Novel functional implications of these findings are hypothesized.

Sperm storage in the spermatheca of the red-back salamander, Plethodon cinereus (Amphibia: Plethodontidae).

In northern Indiana, the mating season of Plethodon cinereus occurs after hibernation from March until June, when oviposition begins. During the mating season, a female stores sperm in its spermatheca, a compound tubular gland in the roof of the cloaca. The apical cytoplasm of the spermathecal epithelium is filled with large secretory vacuoles whose product is released while sperm are stored. Females induced to oviposit in June and July by injections of human chorionic gonadotropin (hCG) still retain much sperm 1 month after oviposition, but secretory vacuoles are absent in all specimens sacrificed in July and August. Instead, some sperm are embedded in the spermathecal epithelium with resultant spermiophagy involving lysosomes. A female sacrificed in September 2 months after oviposition possesses scant sperm, but spermiophagy alone does not seem extensive enough to account for the decrease in sperm numbers. Females sacrificed in October prior to hibernation lack sperm in their spermathecae; some secretory vacuoles are present, but they are not as numerous or as enlarged as in specimens collected in March and May. Inter- and intrafamilial differences in the cytology of sperm storage may not be phyletically informative at the family level but related to species-specific reproductive adaptations.

Sperm storage in Spermathecae of the great lamper eel, Amphiuma tridactylum (Caudata: Amphiumidae).

The spermathecae of ten female Amphiuma tridactylum were examined by light and electron microscopy during the presumed mating and ovipository seasons (March-August) in Louisiana. Spermathecae were simple tubuloalveolar glands in the dorsal wall of the cloaca. Six of the ten specimens were vitellogenic, and all of these specimens contained sperm in their spermathecae and had secretory activity in the spermathecal epithelium. Two nonvitellogenic females also had sperm in their spermathecae and active epithelial cells, whereas the other nonvitellogenic females lacked stored sperm and secretory activity in the spermathecae. In specimens storing sperm from March-May, the sperm were normal in cytology, and secretory vacuoles were contained within the epithelium. In the August sample, however, evidence of sperm degradation was present, and secretory material had been released into the lumen by an apocrine process. We therefore hypothesize that the spermathecal secretions function in sperm degeneration. © 1996 Wiley-Liss, Inc.

The spermathecal epithelium of the queen bee (Apis mellifera): morphology, age-dependent changes and cell contacts

The spermatheca of the honey bee queen is covered by a single-layered, uniform, polarised epithelium. The apical cell surface is greatly enlarged by protrusions and plasma membrane infoldings, the basal cell surface by numerous interdigitating, long, small processes. Cytoplasmic organelles are chiefly represented by mitochondria. Numerous microtubuli extend throughout the cytoplasm. Golgi and endoplasmic profiles are rare. The cells are subject to senile degeneration: with increasing age, a variety of cytoplasmic inclusions appear, among which are myelinated membranes, dense bodies and dense filamentous aggregates. The spermathecal epithelium does not seem to be involved in exocrine secretion related to nutrition of the long-term stored spermatozoa. The ultra-structure points, however, to ion transport functions and to an engagement in the maintenance of an adequate physicochemical environment ensuring the viability of the spermatozoa. Cellular junctions are represented by luminal zonulae adherentes, focal cell-cell adhering junctions and hemiadhering junctions along the basal plasmalemma. Desmosomal contacts and cytoskeletal intermediate filaments are missing. Along the lateral plasmalemma, gap junctions and septate junctions are found.

Annual cycle of sperm storage in spermathecae of the red-spotted newt, Notophthalmus viridescens (Amphibia: Salamandridae).

Female sperm storage was studied in a population of Notophthalmus viridescens from South Carolina. Spermathecae initiate production of a glycoprotein secretory product in October. At this time ovarian follicles are immature (0.5-0.9 mm dia), and mating does not occur despite spermiation in males. Six of the 10 females collected in December had sperm in their spermathecae, indicating onset of mating. Unmated females collected in October and sacrificed in February and March possessed mature ovarian follicles (1.3-1.4 mm dia), and the spermathecae contained large secretory vacuoles 2-3 μm dia. Release of secretory product is concomitant with the appearance of sperm in the spermathecae. Thus mated females lack secretory vacuoles in the spermathecal epithelium, and additional synthesis of secretory product does not occur. All females collected in February and March have mated. Sperm are embedded in the spermathecal epithelium and are undergoing degradation in February. Degradation of sperm in the lumen and epithelium is evident in specimens examined from May and June. Atresia of ovarian follicles begins in April in captive specimens, and specimens captured from the bay in May are spent. A general postbreeding emigration from the pond occurs in summer. Fourteen females collected 7 March were injected with human chorionic gonadotropin (hCG) on 9 March and laid fertile eggs 10-18 March. Two of these females were sacrificed each month from April-September; all retained some sperm in their spermathecae, but further oviposition did not occur. Four females were kept 1 year after oviposition of fertile eggs, and oviposition again was induced with hCG; these eggs were infertile, and spermathecae lacked sperm. Spermathecae are inactive from June-September in captive and wild-caught specimens. Sperm may be stored effectively up to 6 months (December-May), and no evidence was found for retention of viable sperm from one breeding season to the next. © 1996 Wiley-Liss, Inc.