Topic
Gonad
About: Gonad is a research topic. Over the lifetime, 3781 publications have been published within this topic receiving 121916 citations. The topic is also known as: human gonad & reproductive gland.
Papers published on a yearly basis
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Papers
TL;DR: The present paper is an account of some of the investigations on the biology of the perch in Windermere, which are being conducted in connexion with a trap-fishery experiment, which revealed the relative complexity of the interrelationships of length, weight and condition.
Abstract: The present paper is an account of some of the investigations on the biology of the perch (Perca fluviatilis Linn.) in Windermere, which are being conducted in connexion with a trap-fishery experiment (Worthington, 1950). This experiment is mainly a study of populations, but it has been necessary simultaneously to investigate the general biology of the perch, particularly the growth and related aspects. The computation of a formula to express the length,weight relationship and provide a means of interconverting measurements of length and weight, revealed the relative complexity of the interrelationships of length, weight and condition. Condition in turn was found to be correlated with the seasonal changes in gonad development and growth, and the importance of the effect of stomach contents on weight had also to be assessed. It was decided, therefore, to combine these separate but interrelated aspects in one paper. The main part of the paper is devoted to the questions of length-weight relationship and condition. A brief review of the fundamental bases for the concepts of length-weight relationship and condition and of some of the methods of analysis of length-weight data precedes an account of the application of the chosen methods to the present material and its results. This is followed by an account of seasonal changes in gonad weights. A brief account is then given of the rather scanty data available on the weight of stomach contents. The seasonal changes in condition are then described and, finally, some of the results are summarized, combined and discussed as a picture of the seasonal cycle in the Windermere perch. In the statistical analysis of the length-weight relationship the data for only one group of fish are given in full (Tables i and 2) as an example of the method of computation used for all the groups. Again, in the section on seasonal changes in gonad weight and condition Figs. 2-7 are based partly on tables of data which are not published. The full tables have been deposited with the Freshwater Biological Association, from whom copies can be obtained.
4,222 citations
TL;DR: The lability of sex-determination systems in fish makes some species sensitive to environmental pollutants capable of mimicking or disrupting sex hormone actions, and such observations provide important insight into potential impacts from endocrine disruptors, and can provide useful monitoring tools for impacts on aquatic environments.
2,602 citations
TL;DR: The data suggest that the gonads of juveniles from Lake Apopka have been permanently modified in ovo, so that normal steroidogenesis is not possible, and thus normal sexual maturation is unlikely, and the hypothesis that an estrogenic contaminant has caused the current failure in recruitment of alligators on LakeApopka is examined.
Abstract: The reproductive development of alligators from a contaminated and a control lake in central Florida was examined. Lake Apopka is adjacent to an EPA Superfund site, listed due to an extensive spill...
1,231 citations
TL;DR: Variation in the hermaphrodite lineage suggests that cell-cell interaction may play a more significant role in organisms that develop by invariant lineages than has hitherto been considered.
949 citations
TL;DR: RNA interference is used to knock down DMRT1 in early chicken embryos to support the Z dosage hypothesis for avian sex determination, and results indicate that D MRT1 is required for testis determination in the chicken.
Abstract: Sex in birds is chromosomally based, as in mammals, but the sex chromosomes are different and the mechanism of avian sex determination has been a long-standing mystery. In the chicken and all other birds, the homogametic sex is male (ZZ) and the heterogametic sex is female (ZW). Two hypotheses have been proposed for the mechanism of avian sex determination. The W (female) chromosome may carry a dominant-acting ovary determinant. Alternatively, the dosage of a Z-linked gene may mediate sex determination, two doses being required for male development (ZZ). A strong candidate avian sex-determinant under the dosage hypothesis is the conserved Z-linked gene, DMRT1 (doublesex and mab-3-related transcription factor 1). Here we used RNA interference (RNAi) to knock down DMRT1 in early chicken embryos. Reduction of DMRT1 protein expression in ovo leads to feminization of the embryonic gonads in genetically male (ZZ) embryos. Affected males show partial sex reversal, characterized by feminization of the gonads. The feminized left gonad shows female-like histology, disorganized testis cords and a decline in the testicular marker, SOX9. The ovarian marker, aromatase, is ectopically activated. The feminized right gonad shows a more variable loss of DMRT1 and ectopic aromatase activation, suggesting differential sensitivity to DMRT1 between left and right gonads. Germ cells also show a female pattern of distribution in the feminized male gonads. These results indicate that DMRT1 is required for testis determination in the chicken. Our data support the Z dosage hypothesis for avian sex determination.
873 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 60 |
| 2024 | 120 |
| 2023 | 175 |
| 2022 | 350 |
| 2021 | 103 |
| 2020 | 128 |