Extra-ovariolar egg resorption in a dung beetle, Euoniticellus intermedius

Most oösorption in the dung beetle Euoniticellus intermedius takes place in the haemocoele, oöcytes being extruded from the ovariole before the deposition of the chorion. Oösorption can be induced in the laboratory both by prevention of oviposition and by starvation. For up to two days after the onset of starvation the terminal oöcyte appears normal. After three days the prechorionic oöcyte may move through the ovariole wall; the yolk spheres are then disrupted. On the fourth day little yolk remains in the extruded oöcyte, and most of the extruded cells are degenerating. We suggest that extra-ovariolar egg resorption may be a mechanism for ensuring that the single ovariole is not occluded when conditions are suitable for oviposition.     

Fine structure of the developing oocytes in adultArgas (Persicargas) arboreus (Ixodoidea: Argasidae)

The structure of the developing oocytes in the ovary of unfed and fed femaleArgas (Persicargas) arboreus is described as seen by scanning (SEM) and transmission (TEM) electron microscopy. The unfed female ovary contains small oocytes protruding onto the surface and its epithelium consists of interstitial cells, oogonia and young oocytes. Feeding initiates oocyte growth through the previtellogenic and vitellogenic phases of development. These phases can be observed by SEM in the same ovary.The surface of isolated, growing oocytes is covered by microvilli which closely contact the basal lamina investing the ovarian epithelium and contains a shallow, circular area with cytoplasmic projections and a deep pit, or micropyle, at the epithelium side. In more advanced oocytes the shell is deposited between microvilli and later completely covers the surface.Transmission EM of growing oocytes in the previtellogenic phase reveals nuclear and nucleolar activity in the emission of dense granules passing into the cytoplasm and the formation of surface microvilli. The cell cytoplasm is rich in free ribosomes and polysomes and contains several dictyosomes associated with dense vesicles and mitochondria which undergo morphogenic changes as growth proceeds. Membrane-limited multivesiculate bodies, probably originating from modified mitochondria, dictyosomes and ribosomal aggregates, are also observed. Rough endoplasmic reticulum is in the form of annulate lamellae. During vitellogenesis, proteinaceous yolk bodies are formed by both endogenous and exogenous sources. The former is involved in the formation of multivesicular bodies which become primary yolk bodies, whereas the latter process involves internalization from the haemolymph through micropinocytosis in pits, vesicles and reservoirs. These fuse with the primary yolk bodies forming large yolk spheres. Glycogen and lipid inclusions are found in the cytoplasm between the yolk spheres.     

Oogenesis in the annelid Enchytraeus albidus with special reference to the origin and cytochemistry of yolk

In the annelid Enchytraeus albidus the ovary is composed of packets containing eight synchronously developing oocytes. Each oocyte in the packet is connected, via a bridge, to a common cytoplasmic mass. Developmental synchrony of oocytes within individual packets is probably related to the ooplasmic continuity. The young previtellogenic oocyte contains many polysomes, a few cisternae of smooth and rough endoplasmic reticulum, small Golgi complexes, and mitochondria. Many of the mitochondria are dumbbell-shaped and may thus represent division stages. Vitellogenesis is marked by the appearance of peripherally located lipid yolk and small, densely staining granules scattered throughout the ooplasm. There is an increase of smooth endoplasmic reticulum, mitochondria, and enlarged Golgi elements. Small multivesicular-like bodies, the early stages of developing yolk, are derived from the Golgi complex. The mature yolk sphere is bipartite and consists of (a) a variable number of dense spheres, the core bodies, which are produced in the ooplasm by the Golgi complex and which become embedded in (b) a dense matrix. The electron opaque tracer, horseradish peroxidase is incorporated into the oocyte and deposited in the matrix suggesting that this component of the yolk sphere is obtained by micropinocytosis. Enzyme digestions and various cytochemical techniques suggest that the core bodies are rich in carbohydrate, probably as glyco- or mucoproteins, and that the matrix is rich in lipid.     

Verteilungsmuster und Ultrastruktur des Glykogens in der Oocyte vonMusca domestica

Summary Fully grown oocytes ofMusca domestica contain large amounts of glycogen distributed in a characteristic pattern. Three cytoplasmic layers can be distinguished: 1. The periplasm which is free of carbohydrates and merely contains some lipid and protein yolk. 2. A zone of large glycogen clods. 3. Adjacent to this the central ooplasm where numerous lipid droplets and protein yolk spheres are found beside medium size glycogen clods. The glycogen areas are not surrounded by membranes, in contrast to the other yolk inclusions. Some possible interpretations of this ooplasmic pattern, which is already established during oogenesis, are discussed.     

Electron microscope studies on developing oocytes of a coelenterate medusa with special reference to vitellogenesis

In a hydrozoan jellyfish, the female gonad is differentiated from a specialized region of the epidermis near the manubrium. Changes in the oocytes during growth and vitellogenesis are described as observed with electron microscopic and cytochemical techniques. Three major types of yolk are formed; these include lipid, glycogen, and membrane-bound granules consisting of both protein and carbohydrate. The latter first appear evident within vesicular and cisternal elements of the numerous Golgi complexes. The orientation and structural variations noted between the endoplasmic reticulum and forming face of the Golgi complexes suggest that the protein component of the yolk granules may be transferred from the cisternae of the endoplasmic reticulum to the Golgi complex where it is joined to carbohydrate perhaps synthesized by the Golgi complexes. Stages in the release of the precursor yolk material sequestered in cisternal elements of the Golgi complexes are illustrated. The presence of coated and uncoated vesicles in the Golgi regions and their possible role in intracellular transport are described and discussed. The presence and possible method of morphogenesis of vesiculate yolk bodies are also described. What appear to represent invaginations of the oolemma extend into the ooplasm and display a special orientation with respect to lamellae of the rough-surfaced endoplasmic reticulum. Intraooplasmic synthesis appears to constitute the major pathway for protein-carbohydrate yolk deposition.     

Oöcytes degeneration in the queen honey bee after infection by Nosema apis

Terminal o?cytes containing yolk in both healthy and nosema infected queen honey bees were studied. In the healthy queens the terminal o?cytes exhibited a layer of follicular cells which were covered by a smooth-surfaced ovariole sheath. In the o?plasm were numerous electron-dense yolk granules and lipid yolk droplets. The elecron-dense yolk granules exhibited a crystalline structure. Stacks of endoplasmic reticulum were observed in the yolk granules throughout the o?plasm. Numerous mitochondria possessing well defined cristae were also observed. O?cytes in the ovary of queen honey bees appeared degenerated after 7 days of infection by Nosema apis. The ovariole sheath was wrinkled. In the o?plasm, yolk granules were broken down into small spheres and granular substances. Numerous ribosomes without stacks of endoplasmic reticulate were observed. Lysosomes were abundant and numerous electron-dense materials surrounded by a membrane were detected. The o?cytes appeared to be extensively autolysed. The significance of these observations is discussed.     

Glycogen synthesis,storage and transport mechanisms in the yolk-sac membrane of the chick embryo

Summary This paper deals with the relationship of structure and function in the yolk-sac membrane (YSM), a living way station between yolk and embryo of the chick. Through its parenchyma (entoderm) cells all yolk substances, either unchanged or enzymatically transformed into simpler metabolites, are transported to the blood of the growing embryo, wherein they are preeminently utilized as building blocks. Since glycogen must be derived from yolk and is readily visualized in entodermal cells (glycogenic cells of Claude Bernard) of the YSM it was chosen as a marker of functional activity.By a combination of methods of cytochemistry, radioautography and electron microscopy, glycogen localization in the entodermal cells and probable mode of glucose transport into the blood has been investigated during the middle third of embryonic life. The principal findings are: (1) Tritiated glucose injected into the yolk sac is incorporated into glycogen granules in the cytoplasm of entodermal cells. The labeled glycogen granules are arranged in circles about yolk spheres (perilipid pattern) and in basal concentrations next to the plasma membrane (basal pattern). These patterns are identical to those obtained by the periodic acid Schiff test. (2) In electron micrographs glycogen commonly appears as tiny packets of rosettes typically disposed in the cytoplasmic matrix between the yolk spheres but not within them. Differences in patterns of glycogen-organelle organization between apex and base of the entodermal cell suggest a state of flux of glycogen in an apical-basal direction, to wit—from initial synthesis and deposition of glycogen in the apical cytoplasm, to an area rich in glycogen deposits associated with agranular ER, to a basal area of glycogen, ready for breakdown into glucose and transport to blood.Between the glycogen of the basal cytoplasm and the blood of the venous capillary is an ultrastructural complex of perivascular spaces and cell surface membranes having micropinocytic vesicles that are seemingly adapted for the transport of glucose or other metabolites to the blood as well as for the exchange of substances between the entodermal cells and the embryo. As to the mode of uptake of yolk substances from the yolk sac into the entodermal cells, it has been established for the first time thatwhole yolk spheres of different kinds are engulfed by the coalescence of the edge of a cup-shaped fold of the plasma membrane. Pinocytic vesicles of the cell surface membrane seem to provide devices for the uptake of soluble yolk substances.

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Zusammenfassung Diese Arbeit handelt über Struktur und Funktion der Dottersackmembran des Hühnchens. Alle Dottersubstanzen werden, entweder unverändert, oder aber durch enzymatische Reaktionen in einfachere Metaboliten umgewandelt, durch die Entodermzellen der Dottersackmembran dem Blut des Embryos zugeführt. In dieser Arbeit wurde Glycogen als Markiersubstanz der Aktivität verwendet, weil Glycogen aus Dotter abgeleitet ist und in Entodermzellen ohne weiteres nachweisbar ist.Die Lokalisation von Glycogen in den Entodermzellen und der wahrscheinliche Weg des Glucosetransports in das Blut wurde während des mittleren Drittels der Embryonalperiode untersucht mittels cytochemischen, radioautographischen und elektronenoptischen Methoden. Folgende Ergebnisse wurden erzielt: 1. In den Dottersack injizierte, tritium-markierte Glucose wird in Glycogenkörner des Entoderm-Cytoplasmas inkorporiert. Die markierten Glycogenkörner wurden in zwei Anordnungen gefunden: kreisförmig um Dotterkugeln herum, und konzentriert in der Nähe der Basalmembran. Dieselben Anordnungs-Muster wurden auch durch den Periodsäure-Schiff-Nachweis gefunden. 2. Elektronenmikroskopie zeigt das Glycogen in kleinen Rosetten zwischen den Dotterkugeln. Unterschiede im Muster der Glycogen-Organisation zwischen Apex und Basis der Entodermzellen machen es wahrscheinlich, daß Glycogen zunächst im apikalen Cytoplasma synthetisiert und eingelagert wird, sodann in eine glycogenreiche Zone des agranulären Reticulums und schließlich zur Basis der Entodermzellen verschoben wird, wo der Abbau zu Glucose und Transport ins Blut stattfinden. Zwischen dem Glycogen des basalen Cytoplasmas und dem Blut der venösen Kapillaren besteht ein submikroskopischer Komplex von perivaskulären Räumen und Zellmembranen mit mikropinozytären Bläschen, die offenbar für den Transport von Glucose und anderen Metaboliten ins Blut, aber auch für den Austausch von Substanzen zwischen Entodermzellen und Embryo adaptiert sind. Es wurde zum erstenmal gezeigt, daß bei der Aufnahme von Dottersubstanzen in die Entodermzellenganze Dotterkugeln verschiedener Art umschlungen werden, und zwar durch das Zusammenfließen des Randes von schalenförmigen Falten der Plasmamembran. Pinozytäre Bläschen der Zellmembran scheinen verantwortlich zu sein für die Aufnahme von löslichen Dottersubstanzen.

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Supported by contract AT(30-1)-2194 from the U.S Atomic Energy Commission.     

Initiation of Yolk Deposition by Juvenile Hormone

JUVENILE hormone is secreted by the corpus allatum gland, in insects. It was first implicated in the control of yolk deposition in 1936¹ and has recently been found to stimulate fat body synthesis of vitellogenic blood proteins (vitellogenins)^2,3 which are selectively incorporated into yolk by the oocytes^4–6.     

Histological and histochemical studies on the formation of statoblasts of a fresh-water bryozoan,Pectinatella gelatinosa

The course of the statoblast formation in Pectinatella gelatinosa was divided into four stages and studied histologically and histochemically. The bottom of the cystigenous cup is a center of cystigenous cell differentiation and the peripheral zone of the inner cystigenous layer turns to the outer cystigenous layer as the cystigenous cup grows. The annulus is formed by migration and transformation of the outer cystigenous cells. During early stages, the yolk cells have an intensely pyroninophilic or RNA-rich cytoplasm. The cytoplasmic pyroninophilia then diminishes as the amount of yolk granules increases. Several kinds of yolk substances occur in the mature statoblast. During statoblast formation glycogen appears first, then glycoprotein and finally neutral unsaturated lipid. Acid phosphatase activity is associated with granular structures in the cytoplasm. In the cystigenous vesicle, acid phosphatase activity is low and confined to the apical extremity of the cell. Histochemically detectable alkaline phosphatase activity is not involved in the formation of the statoblast.     

OOCYTE DIFFERENTIATION AND VITELLOGENESIS IN THE ROACH PERIPLANETA AMERICANA

The ovary of the roach Periplaneta americana has been studied by techniques of light and electron microscopy. Each ovariole (panoistic type) contains a linear array of oocytes in varying stages of development. Newly formed oocytes become encased by a layer of follicle cells and begin pinocytosis. All subsequent growth stages of the oocytes are dependent, in part, on this phenomenon. All of the pinocytotic caveolae show an unique surface modification; i.e., on their internal surface they have an amorphous or filamentous substance and their external surface is studded with many fine radially oriented spike-like projections. The pinosomes of early oocytes do not contain a demonstrable internal structure; they are thought to contain nutritive substances for the developing oocytes rather than yolk precursors. When the oocyte enters its last stage of growth, characterized by yolk deposition, the caveolae become filled with a dense material which is thought to be the precursors of yolk. Hence the conclusion is drawn that yolk formation is independent of any cytoplasmic organelle system of the oocyte and that the precursors of this deutoplasmic substance are manufactured outside the ovary and are internalized by the process of pinocytosis. Under the phase-contrast microscope the nucleoli of early oocytes are large irregular masses and show the phenomenon of nucleolar emission (fragmentation). These "emissions" become randomly dispersed in the nucleoplasm and some of them come to be intimately associated with the fenestrated nuclear envelope. After this process ceases, the main nucleolar mass becomes vacuolated. Electron micrographs suggest that the constituent particles of the nucleolar emissions migrate from the nucleus through patent pores of the nuclear envelope.     

Fine Structure of the Ovarian Development in the Orb-web Spider, Nephila clavata

ABSTRACT Fine structural changes of the ovary and cellular composition of oocyte with respect to ovarian development in the orb-web spider, Nephila clavata were examined by scanning and transmission electron microscopy. Unlike the other arthropods, the ovary of this spider has only two kinds of cells-follicle cells and oocytes. During the ovarian maturation, each oocyte bulges into the body cavity and attaches to surface of the elongated ovarian epithelium through its peculiar short stalk attachments. In the cytoplasm of the developing oocyte two main types of yolk granules, electron-dense proteid yolk and electron-lucent lipid yolk granules, are compactly aggregated with numerous glycogen particles. The cytoplasm of the developing oocyte contains a lot of ribosomes, poorly developed rough endoplasmic reticulum, mitochondria and lipid droplets. These cell organelles, however, gradually degenerate by the later stage of vitellogenesis. During the active vitellogenesis stage, the proteid yolk is very rapidly formed and the oocyte increases in size. However, the micropinocytosis invagination or pinocytotic vesicles can scarcely be recognized, although the microvilli can be found in some space between the oocyte and ovarian epithelium. During the vitellogenesis, the lipid droplets in the cytoplasm of oocytes increase in number, and become abundant in the peripheral cytoplasm close to the stalks. On completion of the yolk formation the vitelline membrane, which is composed of an inner homogeneous electron-lucent component and an outer layer of electron-dense component is formed around the oocyte.     

An ultrastructural analysis of the dispersed cell phase during development of the annual fish,Cynolebias

Cell ultrastructure was investigated during the dispersion phase of development in the annual fish Cynolebias. Three cellular populations encompass the yolk mass during dispersion, namely, 1) the yolk syncytial layer (YSL) or periblast, which lies directly over the surface of the yolk; 2) the deep blastomeres of the blastoderm, which engage in morphogenetic movements on the surface of the YSL and beneath the enveloping layer prior to forming the future embryo; and 3) the enveloping layer (EVL) of the blastoderm, which is a cohesive epithelium that forms the outermost cell layer of the blastoderm. Deep blastomeres contain numerous mitochondria and scattered glycogen rosettes that appear to function in the utilization of energy reserves. These cells also possess surface extensions such as filopodia and ruffles. Numerous microfilaments running parallel to the plasma membrane occur in cell extensions and in the cortical cytoplasm of neighboring blastomeres. In bleb-like extensions such as ruffles, microfilamentous stress fibers run parallel to the plane of the plasma membrane and prevent cellular organelles from entering the hyaline cap of the ruffle. Deep blastomeres also have basal projections that contain glycogen as well as pits in the basal membrane. Blastomeres move about using the YSL as a substrate. The YSL possesses specializations for nutrient uptake, storage, and transport such as numerous multivesicular bodies and large amounts of glycogen. Glycogen, in the rosette form, occurs in extraordinary amounts, virtually occluding the cytoplasm. Glycogen reserves are postulated to serve as an energy source during diapause. Glycogen is sometimes contained within villous projections that extend from the apical surface of the YSL. This configuration suggests the possibility of glycogen transport to the overlying deep blastomeres. Specializations of the EVL include apical tight junctions and basal lateral zonulae adherentes that interdigitate with those of adjacent EVL cells. The EVL serves as an impermeable membrane that protects the developing egg from the vicissitudes of its environment.     

Oogenesis in Acerentomon gallicum Jonescu (Protura)

Summary Late stages of oogenesis in Acerentomon gallicum Jonescu have been studied by means of light and electron microscopy. Each of the two ovaries of this species consists of a single panoistic ovariole. Late previtellogenic and early vitellogenic oocytes are enclosed in an electron opaque layer, the so-called primary sheath. The precursors for this sheath are most likely synthesized by follicle cells. The yolk develops through autosynthesis, with free ribosomes, dictyosomes and lamellar bodies being involved in the process. Mature yolk spheres contain proteins and polysaccharides. Besides the organelles that take part in vitellogenesis, mitochondria and cisternal stacks of the rough endoplasmic reticulum occur in the ooplasm.This work was supported by Government Problem Grant ii-1.3.13     

The ovaries of aphids (Hemiptera,Sternorrhyncha, Aphidoidea): morphology and phylogenetic implications

The ovaries of aphids belonging to the families Eriosomatidae, Anoeciidae, Drepanosiphidae, Thelaxidae, Aphididae, and Lachnidae were examined at the ultrastructural level. The ovaries of these aphids are composed of several telotrophic ovarioles. The individual ovariole is differentiated into a terminal filament, tropharium, vitellarium, and pedicel (ovariolar stalk). Terminal filaments of all ovarioles join together into the suspensory ligament, which attaches the ovary to the lobe of the fat body. The tropharium houses individual trophocytes and early previtellogenic oocytes termed arrested oocytes. Trophocytes are connected with the central part of the tropharium, the trophic core, by means of broad cytoplasmic processes. One or more oocytes develop in the vitellarium. Oocytes are surrounded by a single layer of follicular cells, which do not diversify into distinct subpopulations. The general organization of the ovaries in oviparous females is similar to that of the ovaries in viviparous females, but there are significant differences in their functioning: (1) in viviparous females, all ovarioles develop, whereas in oviparous females, some of them degenerate; (2) the number of germ cells per ovariole is usually greater in females of the oviparous generation than in females of viviparous generations; (3) in oviparous females, oocytes in the vitellarium develop through three stages (previtellogenesis, vitellogenesis, and choriogenesis), whereas in viviparous females, the development of oocytes stops after previtellogenesis; and (4) in the oocyte cytoplasm of oviparous females, lipid droplets and yolk granules accumulate, whereas in viviparous females, oocytes accrue only lipid droplets. Our results indicate that a large number of germ cells per ovariole represent the ancestral state within aphids. This trait may be helpful in inferring the phylogeny of Aphidoidea.     

Hormonal regulation of trehalose metabolism in the blowfly Phormia Regina Meig.: effects of cardiacectomy and allatectomy at the subcellular level.

1. Kinetic properties of adult Phormia fat body glycogen synthetase were studied and compared to other animals. The KM for UDPG is 2.82 mM, decreasing to 0.58 mM in the presence of G-6-P. 2. The specific activity of fat body glycogen synthetase shows a reduction of 30% within 2 days after allatectomy. 3. Fat body T-6-P synthetase activity decreases to 70% of the control value after cardiacectomy. 4. Corpus cardiacum homogenate fails to induce higher T-6-P synthetase activity in cell-free preparations from cardiacectomized flies. 5. Interactions between corpus cardiacum and corpus allatum in regulating carbohydrate metabolism are discussed.     

Retinal-tectal connections in the embryonic chick: evidence for regionally specific cell surface components which mimic the pattern of innervation.

The chorion surface in the eggs of the annual fishes Cynolebias melanotaenia and C. ladigesi contains an elaborate, three-dimensional species-specific pattern. Two concentric layers form the chorion. The pattern resides in the outer layer, the secondary envelope. It consists of closely packed tubules about 250 Å in diameter. A coat of electron dense “fuzzy” material increases this to 475 Å. The inner layer, the primary envelope, of uniformly low electron density possesses no obvious substructure. Oogenesis is divided into six stages. The oocyte increases in size from 10–20 μm in Stage 1 to 250 μm in Stage 3, 600 μm in Stage 4, and attains maximal size of 900 μm by Stage 6. Massive inclusions of protein and lipid yolk accumulate during Stages 4 and 5. Zone 1, one of the three zones of the primary envelope, first appears late in Stage 2. During Stage 3, Zone 1 is completed and Zone 2 appears between the oocyte surface and Zone 1. The oocyte cytoplasm increases in complexity. Material similar to Zone 1 (light, fibrillar) and Zone 2 (dark, compact) is present in the RER, Golgi, derivative vesicles, and apical pits. Micropyle formation also commences. The oocyte secretes Zone 3 during Stage 4 as thin filaments which consolidate into a highly ordered, transitional structure composed of tangentially oriented bundles of interwoven filaments. These partially fuse during Stage 5 except for fenestrations through which oocyte and follicle cell microvilli pass. Complete fusion during Stage 6 produces a continuous layer. Follicle cells retain an unspecialized structure from Stages 1 through 4. Secondary envelope material accumulates in the RER of the follicle cells during Stage 5. It is secreted and deposited during Stage 6.     

Sequential oogenesis is controlled by an oviduct factor in the locusts Locusta migratoria and Schistocerca gregaria: Overcoming the doctrine that patency in follicle cells is induced by juvenile hormone

In insects that lay eggs in large clutches, yolk accumulation in each of the many ovarioles is restricted to the basal (terminal) oocyte, the one closest to the lateral oviduct. All succeeding (subterminal) oocytes remain small until the terminal oocytes finished their development and were ovulated into the oviduct. The major step regulating yolk uptake by terminal oocytes is the formation of gaps between cells of the follicle layer, a process termed patency. In the migratory as well as in the desert locust, patency is induced by a Patency Inducing Factor (PIF) produced by the lateral oviducts. PIF is secreted in all regions of the lateral oviducts and interacts with the basal follicle cells via the pedicel, a fine duct that connects an ovariole with the oviduct. By this mechanism, patency is triggered in the follicle cells of the terminal oocyte only, restricting yolk accumulation to the oocytes next to ovulation. In contrast to the previous hypothesis, juvenile hormone (JH) is not necessary to induce patency, rather JH amplifies the effect of PIF.     

Effects of precocene II on female-specific hemolymph polypeptides in Oncopeltus fasciatus

Using polyacrylamide gel electrophoresis (PAGE) under denaturing conditions, two major polypeptides of 200,000 and 170,000 daltons were detected in the hemolymph of mature female Oncopeltus fasciatus, but they were not found in the hemolymph of males or newly emerged females. Those polypeptides constituted the two major bands of early vitellogenic oocytes; however, they were absent from the yolk of mature eggs. The slower-migrating band (200,000 daltons) appears to correspond to a vitellogenic protein already identified in O. fasciatus, whose synthesis has been suggested to be independent of juvenile hormone (JH). Treatment of newly emerged adult females with the corpus allatum cytotoxin precocene II prevented the appearance of the female-specific bands and induced an important accumulation of other proteins in the hemolymph. Yolk deposition was also inhibited in those animals. Topical application of JH to precocene-treated females restored the appearance of the 200,000 and 170,000 dalton polypeptides in the hemolymph. These results suggest that JH is required for the synthesis of female-specific polypeptides in O. fasciatus.     

Delayed allatectomy and feeding in Phormia regina (Meig): effects on follicular development.

A delay in feeding a protein meal to the female blow-fly following allatectomy results in inhibition of follicular development in the previtellogenic stage. On the other hand, a protein meal given immediately after the operation permits 55% of the flies that do not deposit yolk in their oocytes fail to do so because of the absence of a corpus allatum hormone necessary for the synthesis of vitellogenin.     

Studies of the reproductive physiology of Cimicidae (Hemiptera)—I. Fecundation and egg maturation

Observations were made under controlled conditions to determine the time required for the spermatozoa to reach various points in their migration. Special organs at the base of the ovarioles serve to hold the sperm until eggs are ready for fertilization. In virgin and mated females egg maturation is similar up to an early stage of yolk deposition, at which time eggs of the virgin females are resorbed. Ligation and implantation experiments indicate that the corpus allatum is essential for egg maturation. Its secretion does not become effective until at least 10 hr after feeding and is required for egg maturation to continue. Virgin females may be induced to produce eggs by corpora allata implants. Implants from males and virgin females as well as mated females are effective. External application of farnesol has an effect on egg maturation similar to corpus allatum implantation.