Common Oviduct Research Articles

Anatomy and Histology of Reproductive Organs of Female <I>Homalodisca coagulata</I> (Hemiptera: Cicadellidae: Proconiini), with Special Emphasis on Categorization of Vitellogenic Oocytes

The anatomy and histology of female Homalodisca coagulata (Say) (Hemiptera: Cicadellida: Proconiini) reproductive organs is described using light microscopy. The reproductive organs of H. coagulata consist of one pair of ovaries, each with 10 telotrophic ovarioles, a pair of lateral oviducts, a common oviduct, a spermatheca, an enlarged genital duct, a complex bursa copulatrix, a vagina, two types of accessory glands, and a genital chamber. The reproductive organs follow the general pattern seen in cicadellids. The complex bursa copulatrix, important in copulation and sperm transfer, is described. A set of morphological criteria were selected, based on the stage of oocyte development, and used to evaluate and assign the rank of ovarian development for field-collected individuals and to assess the overall reproductive status of female insect populations. A principal component analysis of morphological and physiological characteristics suggests that the ovarian ranks reflect the reproductive status of the females. Understanding reproductive status and patterns is critical for determining the optimal time to implement control methods to suppress H. coagulata populations in southern California.

Neuromuscular organization and aminergic modulation of contractions in the Drosophila ovary.

BackgroundThe processes by which eggs develop in the insect ovary are well characterized. Despite a large number of Drosophila mutants that cannot lay eggs, the way that the egg is moved along the reproductive tract from ovary to uterus is less well understood. We remedy this with an integrative study on the reproductive tract muscles (anatomy, innervation, contractions, aminergic modulation) in female flies.ResultsEach ovary, consisting of 15–20 ovarioles, is surrounded by a contractile meshwork, the peritoneal sheath. Individual ovarioles are contained within a contractile epithelial sheath. Both sheaths contain striated muscle fibres. The oviduct and uterine walls contain a circular striated muscle layer. No longitudinal muscle fibres are seen.Neurons that innervate the peritoneal sheath and lateral oviduct have many varicosities and terminate in swellings just outside the muscles of the peritoneal sheath. They all express tyrosine decarboxylase (required for tyramine and octopamine synthesis) and Drosophila vesicular monoamine transporter (DVMAT). No fibres innervate the ovarioles. The common oviduct and uterus are innervated by two classes of neurons, one with similar morphology to those of the peritoneal sheath and another with repeated branches and axon endings similar to type I neuromuscular junctions.In isolated genital tracts from 3- and 7-day old flies, each ovariole contracts irregularly (12.5 ± 6.4 contractions/minute; mean ± 95% confidence interval). Peritoneal sheath contractions (5.7 ± 1.6 contractions/minute) move over the ovary, from tip to base or vice versa, propagating down the oviduct. Rhythmical spermathecal rotations (1.5 ± 0.29 contractions/minute) also occur. Each genital tract organ exhibits its own endogenous myogenic rhythm.The amplitude of contractions of the peritoneal sheath increase in octopamine (100 nM, 81% P < 0.02) but 1 μM tyramine has no effect. Neither affects the frequency of peritoneal sheath contractions.ConclusionThe muscle fibres of the reproductive tract are circular and have complex bursting myogenic rhythms under octopaminergic neuromodulation. We propose a new model of tissue-specific actions of octopamine, in which strengthening of peritoneal sheath contractions, coupled with relaxation of the oviduct, eases ovulation. This model accounts for reduced ovulation in flies with mutations in the octopaminergic system.

Primary homology assessment of structures in the female atrial system among species of the Polycystididae (Rhabditophora, Eukalyptorhynchia)

Abstract. The female atrial system of members of the Polycystididae has been studied at the light microscopical level and compared among the constituent taxa. Based on the criteria of position and conjunction, hypotheses of homology are put forward and compared with the assessments of homology found in earlier literature. Contradictory terminology is synonymized and adapted to fit new findings that recognize homology among structures in different taxa. Based on differences in position and structure, 2 types of female duct are recognized: female duct type I and female duct type II. The term “female bursa” is restricted to a sperm resorbing organ at the proximal end of the female duct type I and/or at the end of a common oviduct. Some species have bundles of glands at the place where the oviduct(s) enter the female duct type I, which are considered homologous among these species. Different types of seminal receptacles are recognized. The term “insemination duct” is restricted to the ducts which in some species, in addition to the oviducts, connect the ovaries with the female duct type I. A single muscular duct, the common oviduct, connects the joined oviducts with the female duct type I in species of Duplacrorhynchus and is considered homologous with the similar duct present in some other species. A uterus is always present, entering the common genital atrium through its frontal wall, or entering a female duct type II. This morphological review of the female atrial system reveals a mosaic distribution of characters if applied to previous phylogenies that are based primarily on the male reproductive system.

Structure of the ovary and the differentiation of follicular epithelium in the pig louse, Haematopinus suis (Insecta: Phthiraptera)

The female reproductive system of the pig louse, Haematopinus suis (Insecta: Phthiraptera) is composed of paired ovaries, lateral oviducts, and a common oviduct that leads into a vagina. Clusters of mycetocytes (= cells filled with symbiotic organisms) are associated with lateral oviducts. Each ovary is composed of five loosely arranged ovarioles of the polytrophic-meroistic type. An individual ovariole is covered by a basal lamina and is composed of a terminal filament, germarium, and vitellarium. The terminal filament is composed of large, disc-shaped cells that are orientated perpendicularly to the long axis ofthe ovariole. The basal part of the terminal filament is separated from the germarium by a well-developed transverse septum. The germarium is short and filled with clusters of oogonial cells. In each cluster the cells arejoined by intercellular bridges, filled with fusomal material. Within the cluster, only one cell, the future oocyte, enters the prophase of the first meiotic division; the other cells differentiate into nurse cells. The basal part ofthe germarium is filled with the somatic prefollicular cells. The boundary between the germarium and the vitellarium is not distinct. The vitellarium contains linearly arranged ovarian follicles in subsequent stages of oogenesis (previtellogenesis, vitellogenesis and choriogenesis). Each follicle consists of an oocyte and 7 nurse cells and is surrounded by follicular cells. During oogenesis the follicular cells diversify, so that ultimately, five morphologically distinct subpopulations of these cells can be distinguished: (1) cells in contact with the nurse cells, (2) anterior cells, (3) mainbody cells, (4) posterior cells, and (5) interfollicular cells. Interestingly, the follicular cells associated with the anterior part of the oocyte, i.e. located in space at the oocyte/nurse cell border (fold cells) are mitotically active throughout previtellogenesis. It might be suggested, in this context, that the separation of the oocyte from the nurse cell compartment is brought about by mitotic divisions, consequent multiplication and centripetal migration of these cells.

Morphology and chemistry of Dufour glands in four ectoparasitoids: Cephalonomia tarsalis, C. waterstoni (Hymenoptera: Bethylidae), Anisopteromalus calandrae, and Pteromalus cerealellae (Hymenoptera: Pteromalidae)

The venom apparatus of four hymenopterous parasitoids, including two bethylids, C. tarsalis (Ashmead) and C. waterstoni (Gahan), and two pteromalids, A. calandrae (Howard) and P. cerealellae (Ashmead), were removed and the associated Dufour glands characterized with respect to their external morphology and chemistry. Dufour glands in all four species have a characteristic translucent appearance that apparently results from their lipid content. The stalked Dufour glands of C. tarsalis and C. waterstoni are pear-shaped and have overall lengths of approximately 0.2 and 0.15 mm, respectively. The thin venom glands are bifurcate and insert through a fine duct into the transparent ovoid- to pear-shaped venom reservoir in these bethylids. In A. calandrae and P. cerealellae the Dufour glands are elongated, tubular structures of ca. 0.35 and 0.8 mm in length, respectively, that constrict to a short stalk that empties into the common oviduct. The venom glands in these pteromalids are simple elongated structures that insert into the sac-like venom reservoir through a fine duct. The chemistry of the volatile contents of the Dufour gland in these four species differs considerably. C. tarsalis Dufour glands contain the same hydrocarbon components as found on the cuticle of this species (Ann. Entomol. Soc. Am. 91:101–112 (1998)), and no other chemicals. The Dufour glands of C. waterstoni also contain only hydrocarbons, most of which are the same as the cuticular hydrocarbons (Ann. Entomol. Soc. Am. 85:317–325 (1992)), but in addition the Dufour gland contains ca. 3% of a mixture of 2,17- and 2,19-dimethyl C 23. A. calandrae Dufour gland chemistry is somewhat more complex than that of either of the two bethylids, but like the bethylids, only hydrocarbons are present. The carbon number range is from C 30 to C 39 and consists of a mixture of n-alkanes (C 30-C 38); 3-, 5-, 7-, 9-, 11-, 12-, 13-, 14-, 15- and 17-methyl alkanes; 3,7- and 3,11-dimethyl alkanes; 5,9- and 5,17-dimethyl alkanes; 7,11-, 9,13-, 13,17-, 14,18- and 15,19-dimethyl alkanes; 3,7,11- and 3, 9,15-trimethyl alkanes; and 3,7,11,15-tetramethyl alkanes. The cuticular hydrocarbons of this species have not been previously reported, but they are the same as the Dufour gland hydrocarbons. The Dufour glands of P. cerealellae contain both hydrocarbons and two long-chain aldehydes. Most of the hydrocarbons are identical to those found on the cuticle of this species (Ann. Entomol. Soc. Am. 94:152–158 (2001)), but in addition, 5,9-dimethyl C 27, 5,13-, 5,17- and 5,19-dimethyl C 35, 12- and 14-methyl C 36, 12,16- and 13,17-dimethyl C 36, 13-methyl C 37 and 13,17-dimethyl C 37 are present. The two aldehydes detected in glands from P. cerealellae are n-tetracosanal (C 23CHO) and n-hexacosanal (C 25CHO).

Female reproductive system of the decapitating fly Pseudacteon wasmanni Schmitz (Diptera: Phoridae)

Pseudacteon wasmanni is a South American decapitating fly that parasitizes workers of Solenopsis fire ants. We used light microscopy (historesin serial-sectioning stained with Haematoxylin/Eosin) and scanning electron microscopy to show and analyze internal and whole external views of the female reproductive system. All specimens analyzed ( n=9) by light microscopy showed post-vitellogenic oocytes inside the ovaries. The lack of typical follicles (oocyte-nurse cell complexes) in all specimens suggests that oogenesis occurs during the pupal stage. The total number of eggs found ranged from 31 to 280 ( X=142±73, SD). The egg has a slugform or torpedo shape (about 130 by 20 μm) with a pointed apex at the posterior pole as defined by the fly; the micropyle appears to be in a depression or invagination at the anterior pole. An acute hypodermic-like ovipositor is evaginated from the hard sclerotized external genitalia during egg laying. The existence of a muscular bulb associated with the end of the common oviduct suggests that the egg is injected into the ant's body by a strong contraction of the bulb which probably is stimulated by bending of several ventral sensilla. During contraction, the abdomen extends out along a large fold between the sixth and seventh tergites in such a way that the sclerotized genitalia is rotated ventrally into a slightly anterior orientation in preparation for oviposition.

Mating behavior, insemination and sperm transfer in the ground beetle Carabus insulicola.

Mating behavior and the processes of insemination and sperm transfer in the ground beetle Carabus insulicola were analyzed. C. insulicola has elaborate genitalia, in which the strongly sclerotized male copulatory piece is inserted into the female vaginal appendix in copula. During mating, I observed pre-copulatory struggles of males and females, as well as delays in ejaculation, suggesting the presence of intersexual conflicts. Insemination was achieved with a spermatophore, which strongly adhered to the openings of the spermatheca, common oviduct, and vaginal appendix. The spermatophore dissolved after copulation, and sperm were transferred into the spermatheca within three hours after copulation. Sperm bundles were contained within the testes and spermatophores, but free spermatozoa were found in the spermatheca.

Expression of allatostatin in the oviducts of the cockroach Diploptera punctata

The cockroach allatostatins (Y/FXFGL/Ia ASTs) are a ubiquitous family of peptides in the invertebrates. They affect numerous physiological processes including the inhibition of juvenile hormone III (JH) biosynthesis, inhibition of muscle contraction, inhibition of ovarian ecdysteroid biosynthesis and inhibition of vitellogenin (Vg) release from the fat body. We have developed and optimized a sensitive and specific quantitative competitive reverse transcriptase polymerase chain reaction (QC-RT-PCR) method to quantify Diploptera punctata AST (Dippu-AST) expression. Using this technique we show that tissues of both lateral and common oviducts and the ovary express message for Dippu-AST. Moreover, the pattern of expression observed in the oviducts and ovary is strikingly similar with significant changes occurring during the reproductive cycle. Specifically, expression of AST is drastically reduced during the time of maximal vitellogenin (Vg) uptake, with higher levels measured prior to and following vitellogenesis. Furthermore, using immunocytochemistry, we have shown Dippu-AST-like-immunoreactivity in the terminal abdominal ganglion, as well as in ventral nerve 7, some branches of which innervate the common and lateral oviducts with other branches innervating the bursa copulatrix and brood sac of mated female D. punctata. The pattern of Dippu-AST expression and immunocytochemical staining suggests that ASTs function, in part, to regulate the cycle of vitellogenesis in mated female D. punctata.

Egg activation and timing of sperm acceptance by an egg in honeybees ( Apis mellifera L.)

Mechanical stresses by a narrow glass capillary were applied to unfertilized eggs of honeybees to determine whether the removal of meiotic blocks of the eggs could be caused by simple mechanical stimuli. The treated eggs developed into the anaphase of the first meiotic division at 15 min after treatment, whereas the untreated eggs remained arrested at the metaphase of the first meiotic division. The results of histological examination of the common oviduct showed that its inner widths were sufficiently narrow to cause the distortion of eggs passing through it. The distorted eggs could be fertilized and develop into diploid embryos if they were exposed to the semen immediately (within 30 sec) after egg distortion. However, this would not happen if the distorted eggs were exposed to semen later (30 min). The eggs exposed to the semen but not given mechanical stimuli could initiate the embryonic development with diploid chromosomes. The interval between mechanical distortion and sperm acceptance by eggs in vitro is compatible with that of natural oviposition of fertilized eggs by honeybee queens. These results suggest that egg activation by mechanical stresses in the common oviduct is valid for the natural oviposition in honeybees.

Reproductive Development of the Tasmanian Eucalypt-defoliating BeetlesChrysophtharta agricola(Chapuis) andC. Bimaculata(Olivier) (Coleoptera: Chrysomelidae: Paropsini)

The reproductive development of the eucalypt-defoliating beetles Chrysophtharta agricola (Chapuis) and C. bimaculata (Olivier) (Coleoptera: Chrysomelidae) was examined by dissecting male and female teneral, overwintering, and reproductive adults. Both species had morphologically similar reproductive systems, except that C. agricola females had more, but significantly smaller, ovarioles and C. agricola males had more testis follicles and significantly larger testes than C. bimaculata. In both species, females had ciliated lateral and common oviducts and no accessory glands. The male aedeagus of both species underwent approximately 180° longitudinal rotation during adult maturation. Both species had consistent integument and haemolymph colour changes from overwintering to reproductive maturity. Twenty percent of female C. agricola, but no C. bimaculata, had mated prior to overwintering. The rate of post-overwintering reproductive development of female and male C. bimaculata was examined at six temperatures.

Structure of the female reproductive system and oogenetic mode in a schizomid, Schizomus sawadai (Arachnida, Schizomida)

Summary The structure of the adult female reproductive system was examined in a schizomid, Schizomus sawadai. The system consists of a single median ovary, a pair of lateral oviducts, and a single common oviduct with a pair of triplets of small seminal receptacles and a simple slit-like genital pore. Smaller previtellogenic oocytes less than 40 μm in diameter are found sparsely scattered in the dorsal ovarian wall among the ovarian epithelial cells, while two size groups of advanced oocytes, larger previtellogenic and vitellogenic, protrude from the lateral and ventral ovarian walls, respectively, accompanied by short cellular stalks. Neither nurse cells nor follicle cells are present around all the oocytes. Oogonia are not found in the adult ovary, indicating the lack of a continued supply of oocytes. The ovarian lumen is connected with the lumens of the lateral and common oviducts, and then with the genital pore. Modes of oogenesis, ovulation, and oviposition, deduced from the structural features of the female reproductive system of S. sawadai, are compared with those in some other arachnids, merostomes and pycnogonids.

Source of the host marking pheromone in the egg parasitoid Trissolcus basalis (Hymenoptera: Scelionidae)

After oviposition, Trissolcus basalis females always mark the host's surface, depositing host marking substances for herself and to warn other ovipositing females. The perception of these host marking substances, probably through the antennae, can induce the female to leave and seek healthy hosts. Parasitoid females exposed to conspecific parasitized egg masses left the host egg masses significantly more often than when exposed to non-parasitized egg masses. More egg mass leaving behavior also was observed when the egg masses were treated with Dufour's gland secretion but not when treated with secretion from the common oviducts. The common oviduct has a secretory epithelium that produces electron-dense vesicles, probably containing proteinaceous substances. The secretory cells of the accessory gland, Dufour's gland, contain electron-lucid vesicles, whose secretion appears to be a lipid similarly to that found in pheromone secreting glands. Ultrastructural and behavioral evidence suggests that Dufour's gland is the host marking pheromone source.

Fate of male germ cells within the male and female genital tract of Ixodes ovatus (Acari: Ixodidae).

In a Prostriata, Ixodes ovatus Neumann (Acari: Ixodidae), the fate and ultrastructural changes of male germ cells were observed during their reproductive behavior including copulation and feeding. Before copulation, male germ cells in the male seminal vesicle were prospermia. After copulation, the timing of spermateleosis and ultrastructural changes during spermateleosis were the same as those in other ixodids. In I. ovatus, endospermatophores were fragmented in the cervical vagina, although they occur within the receptaculum seminis in Metastriata. After fragmentation of endospermatophores, the male germ cells reached a common oviduct, where they were stored for at least 30 days. On day 30 after copulation, the ultrastructure of the male germ cells in the common oviduct was the same as on day 2 after copulation. On the other hand, the male germ cells reached the oviducts on day 4 after engorgement (corresponding to day 9 after copulation). This indicates that feeding advances ascent of male germ cells.

Rhopalobdella japonica n. gen., n. sp. (Hirudinea, Piscicolidae) from Dasyatis akajei (Chondrichthyes: Dasyatididae) in the northwestern Pacific.

A new genus and species of piscicolid leech in the Platybdellinae inhabits the oral cavity of Dasyatis akajei in the northwestern Pacific Ocean near Tanabe, Japan. The genus Rhopalobdella n. gen. is characterized externally by very small oral and caudal suckers and a smooth body that is widest just posterior to the clitellum. Eyespots and ocelli are lacking. The coelom is spacious with large segmental connecting sinuses between dorsal and ventral sinuses. There are 5 pairs of testisacs, an unusually extensive epididymis, and a very large bursa. Conducting tissue is absent. There are 2 pairs of esophageal diverticula and very well developed nephridia. Rhopalobdella japonica n. gen. n. sp. is characterized by a urosome that tapers strongly to the caudal sucker and by a single gonopore; the common oviduct opens into the posterior portion of the bursa. The coelomic and excretory systems resemble Aestabdella, but in other respects the genera are quite different. This is the first marine leech reported from rays in the northwestern Pacific.

Internal female reproductive anatomy and genital interactions during copula in the yellow dung fly,Scathophaga stercoraria(Diptera: Scathophagidae)

Insect genitalia have been extensively studied for taxonomic purposes, but functional anatomy has rarely been examined. We report here on the detailed internal anatomy of the reproductive tract of female yellow dung flies (Scathophaga stercoraria) and the mechanics of copula and sperm transfer. Female dung flies have paired accessory glands, three spermathecae (one singlet and one doublet), each with its own narrow duct, a large muscular bursa copulatrix, which is met by the common oviduct dorso-anteriorly, and paired lateral oviducts and ovaries. The bursa is lined internally with a thick cuticle. During copula and while ejaculating, the male aligns the gonopore with the spermathecal duct entrances to the bursa and pinches the female's abdomen at approximately this point. Sperm packing in the spermathecae appears quite orderly, and structurally the sperm appear typical of many insects. Aedeagus withdrawal appears to remove some bursal sperm. The results are discussed in relation to other Diptera.

Molecular anatomy of an onychophoran: compartmentalized sperm storage and heterogeneous paternity

Onychophorans (peripatus or velvet worms) show extraordinarily high local endemism, and cryptic species are common. As part of a programme addressing issues of endemicity at hierarchical spatial scales, we investigated reproduction in Euperipatoides rowelli (Onychophora: Peripatopsidae) using microsatellite analysis. This species is ovoviviparous, and females have up to 70 embryos in their uteri simultaneously. Batches of undeveloped and well-developed embryos may be present in the uteri of a female. Paired ovaries lead via a common oviduct into paired uteri, each of which has a spermatheca (sperm storage organ). Insemination in E. rowelli is dermal-haemocoelic: spermatophores are placed on the skin of the female, the body wall is breeched, and sperm are released into the haemocoel through which they migrate to the spermathecae. There is no obvious mechanism to prevent sperm mixing, yet microsatellite analysis indicated that offspring in a female's paired reproductive tracts can be sired by different males, and that the paired spermathecae can contain sperm from different males. More than 70% of females had broods with multiple paternity. The data are consistent with the potential for female postcopulatory influence over fertilizations: in particular, compartmentalization of sperm from different males into different spermathecae. Female control of fertilizations could lead to benefits including increased diversity of offspring, minimization of maternal-paternal genetic incompatibility, and influence on offspring genotypes. Multiple mating alone may increase the genetic diversity of offspring: this could be of importance in E. rowelli, which has very small genetic neighbourhoods and low genetic marker diversity.

A mating plug and male mate choice inDrosophila hibisciBock

The functional significance of mating plugs and their relation to male mating behaviour in insects are obscure. InDrosophila hibisci, we describe a firm, gelatinous, mating plug that fills the entire uterus at copulation, and evaluate two nonmutually exclusive hypotheses for the plug’s function: (1) retention of sperm near the openings of the sperm storage organs and (2) inhibition of further matings. Unlike full-sized plugs, smaller plugs produced by previously mated males failed to retain sperm at the anterior end of the uterus, indicating that full-sized plugs prevent sperm backflow away from female storage organs. Sexually mature males failed to copulate with previously mated, young females, suggesting that the plug may also deter rival matings. In newly emerged females, the plug remains within the uterus for up to 4 days after copulation, but in mature females, the plug and ejaculate are expelled whenever the next mature oocyte descends into the uterus from the common oviduct, which may be soon after copulation. Males remained in copula significantly longer with mature females, perhaps to compensate for this greater likelihood of ejaculate expulsion. Males showed a mating preference for young virgins over older virgin and nonvirgin females. This unusual mating preference may confer fertility benefits made available through the effectiveness of the plug in reducing sperm competition.

A Physiological Age-Grading System forNeochetina eichhorniae(Warner) (Coleoptera: Curculionidae), a Biological Control Agent of Water Hyacinth,Eichhornia crassipes(Mart.) Solms.

Neochetina eichhorniaehas a meroistic reproductive system composed of a pair of ovaries each subdivided into two tube-like ovarioles. The ovarioles consist of two main regions, the distal germarium and the proximal vitellarium. The vitellarium houses the developing follicles, which mature sequentially. The two ovarioles in each pair connect proximally via the lateral oviducts. The paired ovaries join one another via the common oviduct. Ovarian development involves two distinct phases: a nulliparous (meaning “no eggs”) phase and a parous (meaning “with eggs”) phase. Each phase undergoes three sequential stages, named N1, N2, and N3 and P1, P2, and P3 for the nulliparous and parous categories, respectively. The degree of maturity of the proximate follicles and the extent of follicular differentiation distinguish the nulliparous stages. The quantity and quality of follicular relics (and, by association, the number of egg ovulations) distinguishes the parous phases. The overall condition of the ovaries can be characterized from the number of developing follicles in the ovarioles as well as the integrity of the follicular cellular material. Samples from field populations in Texas revealed distinct seasonal changes in physiological age structure and condition of the reproductive system. This physiological age-grading system can be an important tool for assessing age structure and relative reproductive health ofN. eichhorniaepopulations or other weed biological control agents with similar reproductive systems.

Development of female accessory glands of Chrysomya putoria (Wiedemann) (Diptera: Calliphoridae) during oogenesis

Females of Chrysomya putoria (Diptera: Calliphoridae) have two sexual accessory glands, which are tubular and more dilated at the distal extremity. The glands open independently into the common oviduct. Two morpho-physiological regions were distinguished in the longitudinal semi-thin sections of the glands. The secretory region is constituted by three layers: a cuticular intima, lining the lumen, followed by a layer of small cells, and then a layer of very large secretory cells. The ductal region of the gland presents only two layers: the cuticular intima and a cellular layer. In both regions a basement membrane is present. Each secretory cell has in its apical region a reservoir, which enlarges throughout oogenesis; in its basal region there is a large nucleus. The ductal cells are cylindrical and smaller than the secretory cells. The glandular secretion is synthesized in the cytoplasm of the secretory cells, stored and/or modified in the reservoir, then drained to the lumen through an end apparatus seen in the apical region of the secretory cell. Histochemical tests indicate that this secretion is a glycoprotein. Measurements of the glands from females at different physiological conditions and fed on different diets correlate with the results obtained for changes in the ovary during oogenesis. Cell number averaged 561.2 ± 77.54 per gland. There was no increase in cell number during oogenesis.

Morphology of the Digestive and Reproductive Systems of Dalbulus maidis and Graminella nigrifrons (Homoptera: Cicadellidae)

The corn leafhopper, Dalbulus maidis (DeLong and Wolcott) (Homoptera: Cicadellidae) is the principal vector of maize rayado fino marafivirus, corn stunt spiroplasma and maize bushy stunt phytoplasma in tropical and subtropical areas of the Western Hemisphere. The black-faced leafhopper, Graminella nigrifrons (Fobes) (Homoptera: Cicadellidae) is the principal vector of maize chlorotic dwarf waikavirus in North America. The morphology of their digestive and reproductive systems was studied by light microscopy, and illustrations were made to aid in dissection and injection of pathogenic inoculum for various vector-pathogen relation studies. In both species, two salivary glands, located one on each side of the head, extend into the mesothorax. Each gland consists of principal and accessory glands. The former contains an anterior lobe and posterior lobe. Two types of acini are present in the anterior lobe, whereas the posterior lobe has four acini. The accessory glands of D. maidis and G. nigrifrons are very similar rod to elbow-shaped structures. The esophagus of both species is a narrow tube originating from the pharynx and extending to the anterior midgut below the filter chamber. The anterior midgut is a large sac-like structure extending from the metathorax through the entire length of the abdomen, and then ascends backward to the anterior of the midgut to form the filter chamber. The filter chamber of D. maidis has a more complex structure than that of G. nigrifrons. There are two pairs of Malpighian tubules in both species. The central tubule is formed from a pair of fused tubules within the filter chamber; the other tubules extend along the front of the hindgut. In G. nigrifrons the three tubules run parallel to each other along the top of the posterior midgut. In D. maidis, the central tubule and one tubule from the other pair run along the interior of the deep loop of the posterior midgut; the other tubule runs along the exterior of the loop. The ovaries of both species contain six ovarioles. Each ovariole consists of a terminal filament, a germarium, developing oocytes and eggs within follicles and a pedicle. The ovarioles contain six follicles. In G. nigrifrons each ovariole usually contains only one egg within the last follicle whereas the ovarioles of D. maidis often contain two eggs. The ovarioles open into the lateral oviduct, common oviduct and the vagina. The spermathecae open into the common oviduct. A collaterial gland and accessory glands are present. The male of both species has two lateral testes each with six follicles. A pair of accessory glands arise at the posterior of each seminal vesicle and open into the lateral ejaculatory duct.