Brood Sac Research Articles

Humoral induction of milk synthesis in the viviparous cockroachDiploptera punctata

Summary Factors that contribute to the onset of milk production by the brood sac of the viviparous cockroach Diploptera punctata were studied. Milk, which normally begins to be secreted on day 20 of adult age, was detected in brood sac tissue by rocket-immunoelectrophoresis. Humoral factors were shown to initiate milk synthesis in that: (1) brood sacs denervated on day 10 initiated milk synthesis normally, and (2) milk synthesis was initiated in brood sacs from 12-to 18–day donors after implantation into 50 day hosts (i.e., actively synthesizing milk). Implanted brood sacs from donors younger than day 10 did not produce milk suggesting that they were not competent to respond to the humoral factors within the host. Brood sacs from 15–day donors implanted into hosts with increasing levels of milk production contained milk in amounts that increased with that of the host. The humoral factors are not derived from the head because decapitation did not prevent the onset of milk synthesis. Milk production began, with a slight delay, in the presence of unfertilized eggs in the brood sac but did not continue to increase. This indicates that developing embryos are not needed to initiate milk production but are needed for its proper timing and subsequent potentiation. Thus, the onset of milk synthesis requires stimulation by humoral factors and development of the competence of the brood sac to respond to them.

Effects of a synthetic precocene on late embryos and subsequent development of the cockroach Diploptera punctata

Precocene III (PIII, 7-ethoxy-precocene II), dissolved in acetone, was applied to eggs in the brood sac of Diploptera punctata females, at 55–56 days or 62–63 days (about 83.5 ± 1.0% or 95.5 ± 1.0% of the gestation period, respectively) after the mother's ecdysis to adult. Controls received acetone alone or no treatment. Acetone itself induced abortion in many instances and reduced the number of surviving progeny from those females that did give birth. These lethal effects were more pronounced after PIII treatment. A portion of the surviving nymphs that had been treated as eggs with PIII developed normally up to the fourth stadium, although the duration of this development, especially that of the first stadium, was longer than in the controls. In contrast, another portion of the nymphs that had hatched from precocene-treated eggs exhibited disturbed development. Treatment of the eggs in 55- to 56-day-old mothers with the highest dose still permitting hatching (40 μg of PIII in 2 μL of acetone, into the brood sac) yielded the highest proportion of disturbed development. In almost all instances of such disturbed development, the moult from the second to the third stadium was greatly delayed and the insects died in or shortly after an unsuccessful ecdysis, some of them exhibiting slightly prothetelic wings. No sign of precocious metamorphosis was observed in the first or second stadium. These results are compared with those in the literature on the effects of surgical allatectomy of the second and later instars of D. punctata. The morphogenetic role of the juvenile hormone in the early part of postembryonic development is also discussed.

Post-embryonic development of the principal retina of a jumping spider. I. The establishment of receptor tiering by conformational changes

The tiered principal retinae of salticid spiders are unique. No other arthropod ocellar retina resembles them anatomically, or sustains equivalently fine spatial acuities. The phylogeny of spiders guarantees that they evolved from far simpler, untiered retinae. The obscure systematic affiliations of the Salticidae preclude a search for extant forms that might offer precursors of the tiered retina, and it is probable that no such forms now exist. We examine the post-embryonic morphogenesis of a salticid principal retina, making a heuristic assumption that the concept of the ontogenetic recapitulation of phylogeny (Haeckel’s 'Law of Recapitulation', now in a literal sense discredited) can, cautiously applied, either (1) indicate how the retina might have evolved, or (2) exclude some arbitrary models of its evolution. By day 3 of post-embryonic development, a presumptive principal retina is established as a simple hemisphere of primordial receptive segments, to which new receptive segments are inferred to be still in the process of being added at the equator. At around days 4-5, the hemisphere of receptive segments starts rapidly to narrow. By around day 10, horizontal narrowing has transformed the initial hemisphere to an approximation of the mature, dorsoventrally aligned, boomerang-shaped retina. At day 12, spiderlings moult to the second instar, but conformational changes to the retina continue until day 15, when spiders leave their brood sacs and become independent. The major conformational changes imply that distal receptive segments (e.g. those of Layers III and IV) are derived from those that initially lie at or close to the equator of the primordial hemisphere; and that foveal Layer I receptive segments remain at the retinal pole. Extreme horizontal narrowing ensures that equatorial receptive segments come to overlie those at the retinal pole, or at least near to it. These findings exclude a hypothesis that receptors of different spectral sensitivities were randomly distributed over a primitive retinal hemisphere, and that tiering was generated during phylogeny simply by their differential migration along lines parallel to the optical axis. Nevertheless, limited local migrations of nascent receptive segments along such lines are inferred to contribute to the final pattern of tiering.

Termination of Pregnancy and Milk Synthesis in the Viviparous Cockroach,Diploptera Punctata: a Role of Juvenile Hormone

Summary Females of the viviparous cockroach Diploptera punctata nourish their embryos with a milk secretion produced by the brood sac wall. Milk content of the brood sac undergoes a decline a few days prior to parturition. We have shown that this decline is dependent on juvenile hormone produced by the corpora allata. Allatectomy either early or late in pregnancy, times when juvenile hormone titer is low, delayed the normal decline of milk in the brood sac. Treatment of allatectomized females with the juvenile hormone analogue, ZR 512, restored the normal decline in the amount of milk. Fine structural analysis as well as injection of radiolabeled precursor demonstrated that the amount of milk in the brood sac at the end of gestation in allatectomized females reflected continued milk synthesis and not merely stasis. Corpora allata were shown to have the additional role of terminating pregnancy. Allatectomy of pregnant females delayed parturition even though it did not affect embryo development. Replacement...

Dendrogaster (Crustacea: Ascothoracida) parasitic in Alaskan and eastern Canadian Leptasterias (Asteroidea)

The ascothoracid parasite Dendrogaster is reported from four boreal localities in the Western Hemisphere. Dendrogaster elegans Wagin infests the sea star Leptasterias polaris in Bristol Bay, Alaska, and in the Gulf of St. Lawrence; the eastern specimens have a shorter brood sac middle piece. A lectotype is selected and described for D. arctica Korschelt from L. groenlandica in the eastern Bering Sea; Siberian specimens previously assigned to this species differ from the type in many details. Immature specimens of an unidentified Dendrogaster species have been found in L. floccosa from the Davis Strait.

Aspects of the Biology of Pseudocarcinonemertes homari and Its Association with the American Lobster, Homarus americanus

Pseudocarcinonemertes homari can reproduce on and destroy the egg mass of both the American (Homarus americanus) and the European lobster (H. gammarus) but does not appear to be a problem for brachyuran species. The eggs of P. homari are subspherical, average 251 × 260 μm, and are contained in individual compartments in a membranous brood sac that is attached to the lobster abdomen or egg mass. An average of 39 eggs occur in a brood sac. Newly hatched larvae are ciliated, lack anterior and posterior tufts, cirri or flagella, and are retained in the brood sac. Larval development is direct, and there is no free-swimming stage. After the larvae break out of the brood sac they join the adults and juveniles on the lobster egg mass. Many lobsters gradually remove infested eggs, but on those that do not, the nemertean population can increase to more than 14 000 individuals. After the lobster eggs are destroyed, the nemerteans disperse. Some form mucoid aggregations at protected sites on the exoskeleton; others move to the branchial chamber and gills or transfer to other lobsters. Reproduction occurs almost exclusively on the lobster egg mass, but P. homari appears capable of reproducing on lobster gills if denied access to lobster eggs for extended periods.

Geographic Distribution and Seasonal Occurrence of the Nemertean Pseudocarcinonemertes homari on the American Lobster, Homarus americanus

Examination of 1041 trap-caught lobsters from the Bay of Fundy, Grand Manan, Browns and German Banks, south and east Nova Scotia, and Northumberland Strait indicated that Pseudocarcinonemertes homari occurs on American lobsters, Homarus americanus, throughout Canadian Maritime waters. Male lobsters were rarely infected and ovigerous females generally had a higher prevalence (percentage infected) and mean intensity of infection (number of nemerteans per infected lobster) than nonovigerous females. Sexually immature nemerteans were found on male and nonovigerous female lobsters, but all P. homari life history stages including brood sacs occurred on ovigerous lobsters. No seasonal trends were evident on ovigerous lobsters caught near Grand Manan; prevalence was consistently high (60–93%) and mean intensity ± SE was variable (15 ± 4.0 to 86 ± 63.1). The nemertean developed to maturity on ovigerous lobsters, reproduced on the host egg masses throughout the year, and appeared to produce three generations during a lobster egg incubation period. When lobsters completed egg incubation, nemertean reproduction ceased and some nemerteans either died, left the lobster, or perhaps were shed at molting. Prevalence and mean intensity increased with the size of ovigerous lobsters, and the distribution of nemerteans among ovigerous lobsters was highly aggregated. Ovigerous lobsters infected with >200 nemerteans had extensively damaged egg masses, but were rarely encountered (5 of 291). The impact of P. homari on the egg mortality of wild populations of H. americanus is unknown.

Morphology and Systematics of the Nemertean Pseudocarcinonemertes homari (Hoplonemertea:Mortostilifera) from the American Lobster, Homarus americanus

Our study of the morphology and systematics of the nemertean Pseudocarcinonemertes homari Fleming and Gibson, 1981 is based on specimens removed from the damaged egg masses of American lobsters, Homarus americanus, caught in the type locality at Grand Manan, N.B., in the Bay of Fundy and nearby Passamaquoddy Bay. Morphological characteristics and measurements of males, females, and developmental stages, obtained through examination of live and preserved nemerteans plus stained histological sections, revealed differences and provided additional indications of variability in measurements of taxonomic characters when compared with the original description. Specifically, female nemerteans are longer and slightly wider than males; the rhynchodael opening is subterminal; sensory bristles occur lateral to the rhynchodael and anal openings; cephalic furrows are observable on living specimens; the combined stylet–basis length is longer than reported and stylet length appears a stable character; the bulbous or sacculate foregut joins to a distinct pyloric tube; ova are large, 260 × 251 μm in length and width; and larvae retained in the membranous brood sac lack anterior and posterior cirri or tufts. Comparison of characters that define Pseudocarcinonemertes and differentiate it from Carcinonemertes with those defining free-living hoplonemerteans strongly supports its removal from the family Carcinonemertidae to the family Tetrastemmatidae.

Regulation of juvenile hormone synthesis during pregnancy in the cockroach, Diploptera punctata

Regulation of juvenile hormone synthesis during pregnancy was investigated after determining the normal rates of synthesis in pregnancy and the second gonadotrophic cycle in Diploptera punctata by direct in vitro radiochemical assay. The low rate of juvenile hormone synthesis during early pregnancy is maintained by three factors: (1) the small ovary which is incapable of eliciting increased rates of juvenile hormone synthesis (2) an inhibitory centre in the brain acting via intact nerves to the corpora allata (similar to that in virgin females) and (3) an inhibitory centre in the brain acting via the haemolymph (elicited by embryos in the brood sac). The existence of two inhibitory centres in the brain is supported by the additive effect of denervating the corpora allata and removing embryos. Whereas these operations alone activated the corpora allata in 54 and 31% of the females, respectively, together they activated 87%, similar to the 91% activated by denervation alone in late pregnancy. The inhibition which remains after denervation of the corpora allata can be removed by decapitation and restored by implantation of the protocerebrum from a pregnant female but not from one developing oöcytes. The inhibition elicited by embryos in the brood sac can be overcome by introduction of a stimulatory ovary and/or substitution of active corpora allata.

The functional morphology of the brood sac in two species of ovoviviparous cockroaches,Byrsotria fumigata(Guerin) andGromphadorhina portentosa(Schaum). 2. Transmission electron microscopy

Summary Ultrastructural examination of the brood sac papillae in the ovoviviparous cockroaches Byrsotria fumigata and Gromphadorhina portentosa has revealed the presence of glandular units typical of the integumentary glands of many insects. Each unit includes a duct which originates within a large columnar secretory cell and passes through a duct or canal cell before opening at a pore on the cuticularised apex of a papilla. The structure of the glandular units from virgin and pregnant animals is described. Comparison of the ultrastructure of these brood sacs with that of the viviparous Diploptera punctata enables the ovoviviparous status of B. fumigata and G. portentonsa to be questioned.

REPRODUCTIVE BIOLOGY OF SOME AUSTRALIAN COCKROACHES (BLATTODEA: BLABERIDAE)

AbstractDuring investigation of the life history of some Panesthiinae species, females were found to contain egg masses of a form previously unknown in natural populations. Those of Panesthia cribrata Saussure and P. australis Brunner comprised a double row of about 20 eggs partially covered by a membrane plus a number of eggs lying outside this oothecal membrane. Eggs of Macropanesthia rhinoceros Saussure and Geoscapheus dilatatus Saussure were in a loosely appressed mass with no membranous covering. P. cribrata and G. dilatatus were found to be ovoviviparous as eggs received only water from the female.In the evolution of oothecae in the Blaberidae there is a trend towards reduction of the oothecal membrane and structure. Ultimate reduction is found in Geoscapheus and Macropanesthia, in which loss of oothecal structure allows eggs to be deposited directly into the brood sac.

The Female Reproductive System of the Australian Gastric Brooding Frog, Rheobatrachus silus (Anura: Leptodactylidae)

The digestive tract of females of the Australian frog Rheobatrachus silus is highly modified to permit the stomach to become a brood sac, but the reproductive tract retains the basic anuran pattern and lacks major modifications. Its only unique feature is a tendency towards asymmetry in the lobes and egg complements of the ovaries. The oocytes are unpigmented and when mature have a mean diameter of up to 4.7 mm. The oocyte complement occasionally far exceeds the number of tadpoles or frogs observed to be carried in the stomach. Comparison with the tree frog Litoria rothii and the fossorial Neobatrachus centralis indicates that R. silus has far fewer ovarian lobes. larger and many fewer oocytes, and a much less convoluted oviduct.

Investigations on ecdysteroids and juvenile hormones and on morphological aspects during early embryogenesis in the ovoviviparous cockroach Nauphoeta cinerea

During early embryogenesis, which is from ovulation (day 0) until dorsal closure (day 19), the quantity of free and conjugated ecdysteroids in the egg cases, as measured by radioimmunoassay (RIA), increases. Thin-layer chromatography (TLC) and high-performance-liquid-chromatography (HPLC) analyses combined with RIA suggest that 20-hydroxy-ecdysone is the predominant ecdysteroid. Hydrolysis of the highly polar products of day-0 and day-17 egg cases by Helix pomatia enzymes indicates the presence of some conjugates of 20-hydroxy-ecdysone, hydrolyzable under these conditions. However, important quantities of RIA-reactive highly polar products are not hydrolyzed particularly in day-17 egg cases. These results demonstrate that the highly polar products of day-0 egg cases are qualitatively as well as quantitatively different from the highly polar products of day-17 egg cases. Morphological investigations show that the peak of 20-hydroxy-ecdysone at the time of the dorsal closure coincides with the synthesis of an embryonic cuticle. Using the Galleria wax test only traces, or no juvenile hormone activity could be detected in embryos during the entire period of early embryonic development. Morphological investigations of the brood sac suggest that this organ is very important to facilitate the initial uptake of water into the eggs. Thereafter the embryos can develop independently of the female when kept in a humid environment.

The inhibition of milk synthesis by juvenile hormone in the viviparous cockroach, Diploptera punctata

The brood sac of the viviparous cockroach, Diploptera punctata, synthesizes a protein rich milk which nourishes developing embryos. Milk is first detected in the brood sac (by immunoelectrophoresis) when the embryos begin drinking and continues to increase in parallel with total protein of the brood sac. When embryos cease drinking, both total protein and milk decline in the brood sac. Premature decline in protein and milk content of the brood sac has been observed after treatment with juvenile hormone (from implanted active corpora allata) or a juvenile hormone analogue (ZR 512 applied topically). The fine structure of the brood sac 7 days after corpora allata implant is consistent with that of gland cells which are not actively synthesizing milk. The effect of ZR 512 is detected in decreased milk content of the brood sac after 24 hr of treatment.

Intraspecific variation of adult Leucochloridium sp. (Digenea) from natural and experimental infections.

The variability of adult Leucochloridium sp. from Norway (63°35′ N,9°45′ E) recovered from natural infections in Larus canus L. and experimental infections in L. canus and Taeniopygia guttata (Vieillot) was studied by light microscopy. The results are compared with five species (Nearctic and Palaearctic) having an experimentally known sporocyst stage (brown-banded brood sacs), and with eight other species with unknown intermediate stage, but placed in the genus Leacochloridium s.str. The five adult species (Leucochloridium variae McIntosh, 1932; Leucochloridium fuscostriatum Robinson, 1947; Leucochloridium perturbatum Pojmanska, 1969; Leucochloridium subtilis Pojmanska, 1969; Leucochloridium fuscum Rietschel, 1970) together with the Norwegian material are regarded as belonging to one species, the Nearctic Leucochloridium variae. The variability and validity of the characters used are discussed.

The mode of breeding for the embryos and larvae and the breeding stages in the pseudoscorpion, Garypus japonicus BEIER

Six stages of breeding for the embryos and larvae in Garypus japonicus were described in order. The breeding phenomenon was studied anatomically and histologically from the viewpoint of a nutritive connection between the mother and the embryos or larvae. The nutritive connection seemed to consist of three processes, viz. the secretion of the nutritive fluid from the ovarian epithelial cells into the ovarian lumen, the transportation of the fluid from the lumen into the brood sac, and the ingestion of the fluid by the embryos and larvae in the brood sac. Although these three processes progressed in different sites and by different manners, some functional and periodical correspondences were found both between the secretory and the transportating processes and between the transportating and the ingesting processes. Hence, the transportating process was regarded as connecting functionally and periodically the other two processes and effectuating the nutritive connection in G. japonicus. Based mainly on these orrespondences, the six stages of breeding were able to be established.

Composition of milk from the viviparous cockroach, Diploptera punctata

Milk was collected from brood sacs with filter paper embryo surrogates, dried, and found to contain 45% protein, 5% amino acids, 25% carbohydrate, and 16 to 22% lipid. The protein fraction contained 12% carbohydrate, predominantly mannose, and, after carbohydrate removal, was resolved by SDS-gel electrophoresis into two bands with molecular weights of about 13,000 and 16,000 daltons. All the common amino acids were found in hydrolyzed protein and as free amino acids; glutamic and aspartic acids were the most abundant. Of the total carbohydrate, 26% was incorporated into protein; the remainder consisted of 4 free sugars, the most abundant of which was mannose. Electrolyte concentrations in the secretion differed from those in the maternal haemolymph in that sodium and chloride were lower and potassium was higher. Lipids consisted of phospholipids, cholesterol, and minor amounts of other lipids, together with a waxy substance which coats the embryos. Gut contents from embryos receiving secretory nourishment contained protein in liquid and crystalline form, and only trace amounts of carbohydrates.

‘Milk’ secretion for embryogenesis in a viviparous cockroach

The brood sac of viviparous Diploptera punctata is a typical insect integumentary gland which secretes a ‘milk’ containing protein and carbohydrate to nourish the developing embryos. During gestation the secretory cells proliferate organelles of protein synthesis and secretion and brood sac wet weight, protein content, synthetic activity and secretory output increase five- to six-fold ; a maximum of 0.4 mg protein was collected in 24 hr from one brood sac in a later stage of gestation. Following parturition, when secretory activity ceases, these parameters fall markedly, and the secretory cells decrease their mass by autophagic regression. Acid phosphatase has been located histochemically in autolysomes and assayed in brood sac homogenates; activity reaches a maximum five days after parturition.

Distribution and innervation of hairs in the brood sac of the cockroach, Diploptera punctata (Eschscholtz) (Dictyoptera: Blaberidae)

In the brood sac of the viviparous cockroach, Diploptera punctata, 3 types of sensory hairs are distinguished on the lumenal surface. Two long slender types (30–80 μ long) are confined to the posterior region, one on the ventral side, the other on the dorsal surface, near the bursa. A third type, short and stout (10 μ long) is found over the entire ventral surface; these are exposed in increasing numbers as the broad sac is unfolded during gestation. The nerve cells associated with the 3 types of sensilla join a branch of ventral nerve 7 from the last abdominal ganglion. Preliminary recordings from this nerve indicate that an increased frequency of afferent impulses accompanies artificial stretching of the brood sac. Three types of non-sensory hairs occur on the posterior surface of the brood sac, one of which may aid in the orientation of the ootheca during oviposition.

A study of sexual receptivity in Blabera craniifer Burm. (Blattaria)

In females of the Blaberidae sexual receptivity is inhibited during the preoviposition period and during gestation. Similarly affected are oöcyte development and corpora allata activity during pregnancy. Roth (1964b) believes causation to be due to the mechanical action of the oötheca, but Engelmann (1964) believes it is due to the intervention of a humoral agent. In normal females of Blabera craniifer sexual receptivity is linked to the presence or absence of the oötheca in the brood sac. If the oötheca is not placed in the brood sac receptivity appears sooner than in a pregnant female. If certain afferent pathways are suppressed (by severing the nerve cord), or upset (by anaesthesia or in surgical controls) during pregnancy, only a partial receptivity is shown: straddling of the female on the male abdomen, ‘licking’ of tergal secretions, but no insertion by the male occurs. Such reactions are repeated over several days, giving an alternation of partial receptivity/non-receptivity which differs from that shown in normal animals. At times desynchronization between the receptivity and laying cycles is observed. This leads to the same conclusion as Roth and Barth (1964) that receptivity is not directly controlled by the corpora allata. We believe that the control ‘centre’ of receptivity has an autonomous rhythm, which is normally hidden but which appears when the afferent pathways are lacking or upset. The control mechanism of mating behaviour is probably a neuro-endocrine mechanism.