Oogonial Cells Research Articles

Germ cell comparative Drosophila mutagenesis: sensitivity and mutation pattern in chemically treated stem cells.

Mutagenesis studies on Drosophila oogonial cells with methylnitrosourea, dimethylnitrosamine, and diethylnitrosamine revealed unexpectedly high rates of sex-linked recessive lethals relative to other male and female germ cell stages. Indeed, the oogonial mutation rates with chemicals are higher than with massive X-ray or neutron exposures of oogonia. Analysis of the distribution of lethals per treated female suggests most of the mutations recovered are of independent origin, with very small levels of clustering of identical mutations. In the male stem cell population (spermatogonia) on the other hand, the distribution of lethals is primarily nonrandom and highly clustered. The nature of the mutational endpoint and the different pattern of germ cell development in the two sexes are the probable causes of this difference. The oogonial sensitivity to chemical mutagens may have important bearing on strategies for assessing human hazard.

The structure of the mature oocyte and zygote of Corynosoma semerme (Acanthocephala)

SummaryObservations made with the transmission electron microscope are described from the free ovaries of sexually mature female Corynosoma semerme (Palaeacanthocephala) from the ringed seal (Pusa hispida). The structure of the mature ovaries consists of a supporting syncytium, oogonial cells and tissue and appears to be basically similar to that already described for 4 other species of Acanthocephala representing the 3 orders of the phylum. A comparison has been made between the organization of the cytoplasm of the mature oocyte and the zygote with reference to the consequences of fertilization. A detailed description is presented of the heterogeneous inclusions that are observed in the cytoplasm of the mature oocyte but not in the zygote. The fate and possible function of the components of these inclusions is discussed.

Bilateral gynandromorphism in Dermacentor andersoni (Acari: Ixodidae): morphologic and cytogenetic analysis.

A Dermacentor andersoni bilateral gynandromorph, removed from a laboratory-reared colony, was studied morphologically using scanning electron microscopy and cytogenetically by means of the aceto-orcein squash technique. The morphological sexual dimorphism was correlated with the chromosomal constitution usually found in each sex [i.e., the morphologically male side had a testis with spermatogonial cells containing 2n = 21 (20 + X) chromosomes and the female side had ovaries with oogonial cells containing 2n = 22 (20 + 2X) chromosomes]. The dimorphism, therefore, is the result of unequal distribution of sex-linked chromosomes rather than control at the gene or physiological level.

Nuclear lamellae in the germ-line cells of gall midges (Cecidomyiidae, Diptera)

Lamellar structures in oogonial and spermatogonial cells of gall midges were found to form a complicated system of intranuclear compartments inside which all heteropycnotic chromosomes present in the germ-line cells of these insects are located. In this way, the heteropycnotic S-chromosomes are separated by the nuclear lamellae from the remaining, decondensed chromosomes (E-chromosomes) of the interphase germ-line nucleus.

Comparative Anatomy of Charophyta: I. Oogonia and Oospores of Tolypella- with Special Reference to the Sterile Oogonial Cell

Comparative Anatomy of Charophyta: I. Oogonia and Oospores of Tolypella- with Special Reference to the Sterile Oogonial Cell

Autoradiographic Studies on the Reproductive System of Philophthalmus hegeneri Penner and Fried, 1963

Adult Philophthalmus hegeneri exposed in vitro to 3H-thymidine showed incorporation of the isotope on autoradiograms over nuclei of actively dividing cells of the testes, ovary, vitellaria, and developing miracidia within eggs. Autoradiograms of worms exposed for 1 hr to 3H-tyrosine showed heavy labeling over the ovary, vitelline cells, and the testes. Timing studies utilizing transplanted thymidine-labeled worms indicated it takes 12 days for oogonial cells to become labeled, migrate through the ovary, and be incorporated into eggs. It took 96 hr for labeled vitelline cells to reach the vitelline reservoir. Spermatogonia labeled in the initial 6-hr exposure took 48 hr to become primary spermatocytes, 72 hr to become secondary spermatocytes, 96 hr to become spermatids, 120 hr to become mature sperm in bundles, and 156 hr to reach the seminal vesicle. Studies with tyrosine-labeled worms transplanted to the host for 5 days indicated adults taken from multiple infections will not self-inseminate when isolated. Similar worms transplanted with unlabeled worms exclusively cross-inseminate. In a study on an eye fluke of birds, Philophthalmus megalurus, utilizing techniques of radioisotopic labeling, autoradiography, and transplantation, Nollen (1968a) was able to study several aspects of reproductive physiology and behavior. Timing of stages of gametogenesis and migration of vitelline cells as well as patterns of sperm transfer in single and multiple infections were determined in this study.Nollen found these flukes can selfinseminate in isolation but preferentially crossinseminate in multiple infections. Philophthalmus hegeneri, an eye fluke of shore birds in Florida, differs in several ways from P. megalurus. Among these are the apparent lack of self-insemination when adult P. hegeneri are grown in isolation (Fried, 1962). The ability of the snail intermediate host, Batillaria minima, to survive long periods out of the water makes it ideal for shipping. Thus we have been able to raise adult worms in chicks from larval stages shed by snails collected in Florida. The techniques utilized by Nollen (1968b) were applied to a study of P. hegeneri to see if species differences are apparent in reproductive physiology and behavior when compared to P. megalurus. MATERIALS AND METHODS Philophthalmus hegeneri was obtained from naturally infected Batillaria minima collected from Received for publication 2 March 1973. * Supported by the United States-Japan Cooperative Medical Sciences Program administered by NIAID: Grant Al 09330. Clearwater Harbor, Largo, Florida. Cercariae shed from snails encysted in finger bowls and were stored in aerated seawater not longer than 4 days before use. Metacercariae were induced to excyst by replacing seawater with warm (40 C) saline (0.85%), and day-old chicks (Big H Foods, Fairbury, Ill.) were infected by pipetting the metacercariae directly into the orbit. Worms were removed from the conjunctival sacs of chicks after 35 to 45 days of growth and exposed at 38 to 39 C in small stender dishes to tritiated compounds (Amersham/Searle Inc.) diluted with HedonFleig's saline. The radioisotopes used were thymidine (methyl-3H; 22.4 Ci/mmole) at 75 ,uCi/ml and L-tyrosine (-3,5-T; 1 Ci/mmole) at 100 iCi/ml. Worms were exposed to 3H-thymidine for periods of 6 hr or more to determine the time needed for optimum labeling of the cells of the reproductive system. Similar exposures were carried out with 3H-tyrosine to determine areas of incorporation in the tissues of P. hegeneri. After exposure, worms were either killed immediately in alcohol-formalin-acetic acid (AFA) or returned to the conjunctival sacs of uninfected chicks for varying periods of time. Techniques for autoradiography and transplantation of the exposed worms are described by Nollen (1968b).

Chromosome pairing in the oögonial cells of Drosophila melanogaster.

Pairing between two nonhomologous chromosomes, one a free X-duplication and the other a free fourth chromosome, has been observed cytologically with high frequencies in the oogonial cells of Drosophila melanogaster. The frequencies of nonhomologous pairing ranged from 27 to 47% and showed a positive correlation with the similarity in size between the two participating nonhomologues. Partial homology increased pairing frequency between nonhomologues in the oogonial cell, in contrast to the behavior of the same nonhomologues at distributive pairing in the oocyte, where pairing is strictly size-dependent. Pairing between homologues in the same oogonial cells occurred at a frequency of only 71% and was higher for the autosomes (73%) than for the sex chromosomes (66%). An increased frequency of homologous pairing was found for older gonial cysts (4-cell, 72.0% ; 8-cell, 76.1%) as compared with younger cysts (1-cell, 59.1% ; 2-cell, 53.1%).

Radiosensitivity of developing reproductive cells in female Cochliomyia hominivorax.

In female Cochliomyia hominivorax, radiation-induced dominant lethal changes in the reproductive cells (which develop synchronously) were measured by egg-hatchability tests and correlated with cytological observations of the stage of nuclear development. In pupae 4 to 6 days olds only oogonial cells are present. Irradiation at this age reduced the number of mature oocytes produced as the dose increaseds but the lowered hatchability of eggs that were produced indicated that some dominant lethals persisted through maturation to be detectable in the embryo. In old pupae and newly eclosed adults, differentiation of the oocytes and nurse cells takes place. Irradiation of adults less than 24 hours old interfered considerably with egg production; the younger the female at irradiations the fewer normal eggs were produced. Irradiation of females older than 24 hours resulted in production of normal numbers of eggs. In three-day-old females the oocyte nucleus is in prophase I, in four-day-old females metaphase is and in five-day-old females anaphase I. Dosage-response studies indicated that the LD/sub 50/ radiation dose for oocytes in metaphase I is 1,309 r, anaphase I, 1,689 r, and prophase I, 7,989 r. For more » oocytes irradiated in the first meiotic divisions the relation between dose and dominant lethals induced was linear for the range investigated. (auth) C « less

The distribution of x-ray induced crossovers from Curly inversion heterozygotes of drosophila melanogaster females.

That crossing may occur in oogonial cells was suggested by the results of experiments by Whittinghill [1] in which crossing over was induced by x-rays in the X-chromosomes of Drosophila females homozygous for the c3G asynaptic factor. It had previously been demonstrated that induced crossovers recovered from Drosophila males were of spermatogonial origin [2,3]. Cooper's observations [4] of chiasmata in gonial cells of both sexes of Drosophila may provide cytological foundations for the hypothesis of gonial origin of some crossovers, particularly those which are x-ray induced. Somatic crossing over, the basis for the occurranece of twin spots in the hypodermis of Drosophilamales and females [5], closely parallels gonial crossing over in the formation of daughter cells which have become homozygous distally. The possible consequences of oogonial crossing over upon linking data, as recently discussed by Whittinghill [6], illustrate the need for further investigation of this phenomena. This paper reports the results of x-ray induced crossing over in Curly inversion heterozygotes of Drosophila melanogaster females, and these results are interpreted in relation to normal, or random, meiotic events as opposed to oogonial events of recombination.

Consequences of crossing over in oogonial cells.

Consequences of crossing over in oogonial cells.

Polyploidy in <i>Habrobracon</i> Induced by Colchicine Treatment

1. Coichicine was used to induce polyploidy in Habrobracon pectinophorae. Eggs, larvae, pupae or adults were treated by 0.025, 0.05 or 0.1 percent aqueous solution of colchicine for various length of time.2. 0.05-0.1 percent solution of this chemical was effective for the production of polyploidy.3. Polyploidy was obtained in the spermatogonial cells by treating the male larvae. These cells, however, seem to degenerate without becoming functional sperms.4. On the other hand, tetraploid oogonial cells induced by the treatment of adult females may become tetraploid eggs, which, after reduction, develop into impaternate diploid females or diploid males.5. Thus 130 impaternate females and at least 6 diploid males were produced by 44 treated females.6. Many abnormal males and females with very short antennae were produced by the treatment of larvae.7. Abnormal males having defects not only in external genitalia, Malpighian tubules, but also in gut were produced by the treatment of ovarian eggs.I wish to express my heartfelt gratitude to Prof. Taku Komai for his suggestion of the work and also for his kind guidance in the course of the experiments.

Polyploidy in <i>Habrobracon</i> induced by colchicine treatment

1. Coichicine was used to induce polyploidy in Habrobracon pectinophorae. Eggs, larvae, pupae or adults were treated by 0.025, 0.05 or 0.1 percent aqueous solution of colchicine for various length of time.2. 0.05-0.1 percent solution of this chemical was effective for the production of polyploidy.3. Polyploidy was obtained in the spermatogonial cells by treating the male larvae. These cells, however, seem to degenerate without becoming functional sperms.4. On the other hand, tetraploid oogonial cells induced by the treatment of adult females may become tetraploid eggs, which, after reduction, develop into impaternate diploid females or diploid males.5. Thus 130 impaternate females and at least 6 diploid males were produced by 44 treated females.6. Many abnormal males and females with very short antennae were produced by the treatment of larvae.7. Abnormal males having defects not only in external genitalia, Malpighian tubules, but also in gut were produced by the treatment of ovarian eggs.I wish to express my heartfelt gratitude to Prof. Taku Komai for his suggestion of the work and also for his kind guidance in the course of the experiments.

On an ascomycetous fungus attacking Riccia himalayensis St.

Summary 1. An ascomycetous fungus attacking Riccia himalayensis in Madras is described in detail. 2. The mycelium is intracellular and is confined to the gametophyte portion of the liverwort. 3. Many spermogonia and perithecia are formed by the fungus, and their development is followed in detail. 4. In the spermogonium, numerous uninucleate spermatia are abstricted from the ends of the radially arranged sterigmata and escape outside. The spermatia are non-functional and the spermogonia are merely vestigial organs. 5. During the development of the perithecium, a branched hypha is formed bearing a number of oogonia, but no ascogenous hyphae are formed by the oogonia. Through the profuse development of the paraphyses the oogonial cells are pushed to the base of the perithecium and finally degenerate into a plasmodial mass. Ascogenous hyphae then start from the ordinary vegetative hyphae at the base of the perithecium and grow through the plasmodial mass upwards. Numerous asci are formed by the ascogenous hyphae. The fully developed asci contain eight uniseptate spores. 6. Numerous sclerotia are formed by the fungus in the thallus of the Riccia. The sclerotia are probably perennating structures which serve to infect new liverworts in the next rainy season.

Diploid Males and Triploid Females of the Parasitic Wasp, <i>Habrobracon pectinophorae</i> Watanabe

1. The production of diploid males in the parasitic wasp, Habrobracon pectinophorae Watanabe was studied by using two recessive mutant characters, white and curved.2. The frequency varied according to the hereditary factor involved. Higher frequency was obtained in the case when white was used than in other cases.3. The fertility of diploid males is very high in this species as compared with the American species, H. juglandis. Especially high fertility was found in the case of curved. Therefore, the fertility of diploid males also depends on the hereditary factor involved.4. The daughters of the diploid males laid many eggs which, however, failed to hatch, though embryos were formed within.5. The chromosome complexes of all the types of males and females were studied. The diploidy of biparental males and triploidy of their daughters have been confirmed definitely. In the triploid females, haploid, diploid and triploid chromosomes seem to be mixed in the oogonial cells.6. A gynandromorph with diploid male parts and a haplo-diploid mosaic male are described.I wish to express my heartfelt gratitude to Prof. Dr. T. Komai for his suggestions and kind guidance during the course of this work. I am also indebted to Messrs. T. Hama, K. lyatomi, J. Sonan and M. Nakayama for their kindness in supplying me with the material.

Sex Studies of Schistosoma japonicum

Sex Studies of Schistosoma japonicum