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A gonad, sex gland, or reproductive gland [1] is a mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. [2]
ot. The genital ridge from which either the ovary or testis is formed. o. The left ovary: t. Testis in the place of its original formation; t', together with the dotted lines above, indicates the direction in which the testis and epididymis descend from the abdomen into the scrotum. Skene's glands a.k.a. paraurethral gland: pr. Prostate: u. Uterus.
The ovary is thus formed mainly from the genital ridge and partly from the mesonephros. Later the mass is differentiated into a central part, the medulla of ovary, covered by a surface layer, the germinal epithelium. Between the cells of the germinal epithelium a number of larger cells, the immature ova, are found.
Differentiation between the sexes of the sex organs occurs throughout embryological, fetal and later life. In both males and females, the sex organs consist of two structures: the internal genitalia and the external genitalia. In males, the gonads are the testicles and in females, they are the ovaries.
Sex cords are embryonic structures which eventually will give rise (differentiate) to the adult gonads (reproductive organs). [1] They are formed from the genital ridges - which will develop into the gonads - in the first 2 months of gestation (embryonic development) which depending on the sex of the embryo will give rise to male or female sex ...
The ovary is differentiated into a central part, the medulla of ovary, covered by a surface layer, the germinal epithelium. The immature ova originate from cells from the dorsal endoderm of the yolk sac. Once they have reached the gonadal ridge they are called oogonia. Development proceeds and the oogonia become fully surrounded by a layer of ...
Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. [1] [2] Sex determination is often distinct from sex differentiation; sex determination is the designation for the development stage towards either male or female, while sex differentiation is the pathway towards the development of the phenotype.
The life cycle of land plants involves alternation of generations between a sporophyte and a haploid gametophyte. [25] The gametophyte produces sperm or egg cells by mitosis. The sporophyte produces spores by meiosis, which in turn develop into gametophytes. Any sex organs that are produced by the plant will develop on the gametophyte.