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At least 19 recordsLinked to original sources
PubMed1978

The role of X-linked lethal and viable male-sterile mutations in male gametogenesis of Drosophila melanogaster: genetic analysis.

The possibility that viable male-sterile mutations occur in vital genes and the role played by lethal mutations and viable male-steriles in male gametogenesis were studied. Five sterile loci were identified among the 30 most proximal vital loci of the X-chromosome and two of them were shown to be allelic with lethal mutations. Fertility test on gynanders for nonautonomous lethal mutations proved that vital genes operate autonomously in male gonads, independently of their effect on somatic tissues. Fertility tests of ts lethals, shifted to the nonpermissive temperature after the TSP, showed that 40% of vital genes function in male gonads. It is further shown that about the same proportion of vital genes is operating in female gonads and that the two groups overlap by about 70%. The role of viable and lethal male gametogenesis is discussed in detail.

Drosophila melanogaster↗
PubMed1977

Evidence for postmeiotic expression of ribosomal RNA genes during male gametogenesis.

Pre- and postmeiotic stages of male gametogenesis of 10 different vertebrate species belonging to mammals, birds, amphibians, and fishes were subjected to the Ag-AS staining technique (Goodpasture and Bloom, 1975). A uniform pattern of silver-staining is observable during spermatogenesis of the different vertebrate species. Silver-staining is present in spermatogonia and during the whole period of meiotic prophase, but totally absent during diakinesis and metaphase II of meiosis. In early spermatids silver-staining reappears and only disappears around the beginning of elongation of the spermatid nucleus. Since the Ag-AS technique is believed to stain only transcriptionally active nucleolus organizer regions, our findings indicate that ribosomal RNA genes become reactivated in the haploid spermatid.

Animals↗
PubMed2026

Molecular Regulation of Primordial Germ Cell Specification and Implications for In Vitro Gametogenesis.

Primordial germ cells (PGCs) are the embryonic precursors of gametes, essential for transmitting genetic and epigenetic information across generations. However, PGC specification occurs within a narrow developmental window and involves only a small number of cells, making it difficult to study in vivo. In vitro models using pluripotent stem cells have enabled the generation of primordial germ cell-like cells, but these systems often rely on exogenous signaling and exhibit variability in efficiency and epigenetic fidelity. In this review, we synthesize current understanding of PGC specification in mouse and human systems, emphasizing the integration of signaling pathways, transcriptional networks, epigenetic reprogramming, and metabolic regulation. Canonical regulators, including PRDM1, PRDM14, TFAP2C, and SOX17, function within a broader, interconnected network that establishes for PGC competence. Understanding these interactions will be crucial for advancing in vitro gametogenesis and improving mammalian reproduction.

mammalian reproduction↗
PubMed1976

Gametogenesis in planktonic foraminifera.

Gametogenesis in Globigerinella aequilateralis and Globigerinoides sacculifer in culture is preceded by sinking of the organism and loss of its spines. Hundreds of thousands of flagellated gametes, about 5 micrometers in diameter, are produced within the parent shell and released within a period of 13 hours.

Male↗
PubMed1979

Additional pedigree supporting the frequent origin of XXYY from consecutive meiotic non-disjunction in paternal gametogenesis.

A 48,XXYY Sardinian patient, born to a 46,XX mother heterozygous for the Gd Mediterranean mutant, and to a 46,XY father hemizygous for the same mutant, was found to have a mosaic distribution of G6PD(+) and G6PD(-) peripheral red blood cells. The most likely interpretation of this finding is that the propositus is an additional example of an XXYY zygote derived from a consecutive meiotic non-disjunction during paternal gametogenesis.

Adult↗
PubMed1977

Effects of a juvenile hormone mimic on male and female gametogenesis of the mud-crab Rhithropanopeus harrisii (Gould) (Brachyura: Xanthidae).

1. Effects of ingestion and topical application of 1.30 ppm methoprene, an insect juvenile hormone (JH) mimic, include gametogenesis disorders in both male and female mud-crab Rhithropanopeus harrisii. 2. Progressive inhibition of vitellogenesis and stimulation of spermatogenesis take place after a short exposure time (12-15 days), whereas a longer period (between 30 to 45 days) promotes inhibition of both spermatogenesis and vitellogenesis. Such modifications demonstrate the chemosterilizing action of methoprene on crustaceans. 3. Stoppage of vitellogenesis is characterized by a blockage of oocytes at terminal previtellogenesis and proliferation of the follicle cells involved in vitellogenic oocyte lysis. Spermatogenic degeneration begins with the amalgam of spermatocyte clusters in meiotic prophase and pycnosis of gonia. 4. Analogies between these results and those obtained from experiments involving androgenic gland implantations or the consequences of their hyperfunctioning are discussed.

Animals↗
PubMed1977

[Autoradiography after tritiated thymidine labeling of the abortive gametogenesis in hybrid male ducks from the cross male Pekin X female Barbary].

This autoradiographic data concludes that meiotic prophase of the abortive gametogenesis of the sterile hybride drake (from the mating Peking male = Anas platyrhynchos L. X Barbary female = Cairina moschata L.) lasts 5 days 1/4. 6 days after the injection of the marker the seminiferous tubules contain numerous labeles necrosing cells but never typical elongated spermatids.

Animals↗
PubMed1979

Effect of oestrogenic, and androgenic and gestagenic hormones on the gametogenesis (oogenesis and spermatogenesis) in the snail Helix pomatia.

In the ovotestis of Helix pomatia both oogenesis and spermatogenesis were influenced by treatments with steroid hormones produced in the gonads of higher vertebrates. Testosterone influenced gametogenesis to a small degree. Progesterone and oestrone-acetate at first stimulated ovogenesis, but they also acted on spermatogenesis. All three hormones examined influenced oogenesis in a conspicuous and significant way, while their effect on spermatogenesis was indistinct.

Animals↗
PubMed1978

Kinetics of gametogenesis. II. Comparative autoradiographic studies of oogonia and multiplying prospermatogonia of the Wistar rat.

In the rat the last generation of oogonia and multiplying prospermatogonia (M-prospermatogonia), frequently arranged in synchronized clusters, enters mitosis on about day 17 post conception (p.c.). The duration of the S-phase D-S-Duration and the minimal generation time Tmin of both kinds of "gonia" were determined by the method of labeled mitoses (22 female and 22 male fetuses derived from 11 pregnant rats were sacrificed from 2 to 22 h after a single i.p. injection of 3H-thymidine on day 17 p.c.). Three curves, derived from the labeled prophases, metaphases and the postmitotic descendents of oogonia and M-prospermatogonia--oocytes and primary transitional prospermatogonia (T1-prospermatogonia)--were evaluated. It was demonstrated that the curves as well as the calculated values of D-S-Duration and Tmin are very similar for oogonia and M-prospermatogonia. D-S-Duration ranged from about 10 to 12.5h (10 h read off from the curves of labeled metaphases), Tmin from 16.5 to 18 h (16.5 h read off from the curves of labeled metaphases).

Animals↗
PubMed1977

Characterisation of male meiotic-sterile mutations in drosophila melanogaster. The genetic control of meiotic divisions and gametogenesis.

Male meiotic sterile mutations were selected among X-linked male-steriles by detection of micronuclei in early spermatids. Despite severe defects in the 1st or 2nd meiotic spindles in all mutants, no effect on mitosis was observed. Various features of spindle structure, chromosome segregation, and centriole movements were compared in seven meitoic steriles and in XO males. Chromosome behaviour and centriole movement were always affected concomitantly, and were both shown to be genetically independent of "centre" formation in the meiotic spindles. Precocious and delayed centromere separation was observed in the various mutants in both divisions, and similarly attributed to basic spindle lesions rather than chromosome defects. Attachment of the centriole body to the membrane of the spermatid nucleus was normal only in mutants where second division nuclei were formed. The role of the centriole body was shown to be independent of membrane attachment.--The phenomena observed in this study were discussed mainly with regard to genetic interdependence of morphogenetic processes during male meiosis. A common base for the pleiotropic defects of meiotic steriles and XO males is suggested, and the genetic control of meiosis is re-evaluated in the light of comparison with fertile meiotic mutants.

Animals↗
PubMed1979

Observations on gametogenesis in Plasmodium falciparum from continuous culture.

Gametocytes of Plasmodium falciparum were produced in continuous cultures but eventually declined in numbers after 3--4 months in vitro. Their development progressed in a consistent pattern, from small rounded, through triangular, to ellipsoidal, and finally after 8 days to crescentic forms. Morphologic maturity occurred at 8--9 days, but the gametocytes would not exflagellate in vitro, even after 14--18 days of development. Thus, current culture methods cannot produce a continuous supply of functional gametes for further studies.

Adolescent↗