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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the organs that form the sexual products (ova and spermatozoa) in animals and man.

The gonads are either male organs (testes), female organs (ovaries), or hermaphroditic (for example, in Platyhelminthes and Oligochaeta, the leeches, the majority of Gastropoda, and the barnacles). In the embryos of vertebrates the gonads are found in the sides of the dorsal mesentery in the form of sex folds (paired longitudinal folds of epithelium that line the body cavity), into which migrate the primary sex cells (which arise outside the gonads at earlier stages of the body’s development) and into which grow columns of mesenchymal cells from the truncal kidney (the mesonephros), which participate in formation of the gonadal stroma (in particular, their medullary layer). The epithelium of the gonads becomes cylindrical and its cells may be converted into germ cells (so that it is called the germinal epithelium). In fishes the sex folds arise along the entire length of the body cavity and are converted completely to gonads. In amphibians the folds are similarly situated, but only the middle part is converted to gonads. In reptiles, birds, and mammals the sex folds appear only in the region of the lateral surface of the anterior half of the mesonephros, which faces the mesentery. The germ cells multiply, grow, and mature in the gonads. The growth of the germ cells in the gonads takes place under the influence of the gonadotrophic hormones of the pituitary and by means of special nurse cells—Sertoli’s cells (in male gonads) and follicle cells, which in many animals form a follicular membrane around the ova (in female gonads). Both sexes in the process of gonadal development pass through an undifferentiated (bipotential) stage of development, after which their sexual differentiation begins. The ovaries are formed principally from the cortical layer of the gonads, and the testes from the medullary layer. The form of the ovaries differs markedly in different animals (for example, they are tubular in round-worms and insects, racemose in birds, and dense rounded bodies in mammals). The testes in all vertebrates, beginning with the frogs and toads, are constructed of seminiferous tubules, which communicate with the ductus deferens, formed from the tubules of the mesonephros. In higher animals the gonads are also endocrine glands, secreting sex hormones into the blood. The gonads, their conduction paths, and the external sex organs, constitute the genital system.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The most common cause is CAH due to 21-hydroxylase deficiency (95%).22 Gonads are symmetrical ovaries and uterus is present.
Now referring to sexuality, the simultaneous presence of both male and female traits (gametes) in the same individual (gonad) of any species that is gonochoric during all their life refers to intersexuality and its variants (e.g., hermaphroditism) (Grilo and Rosa, 2017).
Reproductive biology of Holothuria leucospilotu in the Cook Islands and the implications of traditional fishing of gonads on the population.
These results indicated that eyestalk ablation promoted food consumption, feeding intensity, gonad development, and energy conversion efficiency of P.
The ovaries of the smooth lumpsucker are characterized by the absence of sperm in all gonads, indicating gonochorism, oviparity, and external fertilization (Devlin and Nagahama, 2002).
Table 1: Heavy metals (Pb-Lead; Cd-Cadmium; Ni-Nickel) in the liver, gill, kidney, gonad and muscle of Rui (Labeo rohita), Katla (Gibelion catla) and Pangus (Pangasius hypophthalmus) fishs from Kawran Bazar fish market.
Histology of gonads plays a very important role in studying the reproduction of the species.
In conclusion, in patients with gonadal dysgenesis or ovotesticular DSD, laparoscopic examination is the most sensitive and specific imaging modality for the evaluation of Mullerian derivatives and undescended gonads. This procedure has additional advantages, such as the potential to perform a gonadal biopsy for histopathological diagnosis or a gonadectomy to prevent or treat malignancy development.
At that moment, the gonads of six organisms were dissected and frozen in liquid nitrogen for later determination of the effects of transportation and to establish the quality and shelf life at day 0.