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The embryological origin of granulosa cells remains controversial. In the 1970s, evidence emerged that the first cells to make contact with the oogonia were of mesonephric origin. It was suggested that mesonephric cells already closely associated with the oogonia proliferated throughout development to form the granulosa cell layer. [2] [3] [4]
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] The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells
In embryology, the genital ridge (genital fold or gonadal ridge) is the developmental precursor to the gonads. The genital ridge initially consists mainly of mesenchyme and cells of underlying mesonephric origin. Once oogonia [clarification needed] enter this area they attempt to associate
The gonads have an important role in germ cell development, converting the bipotential cells into gametogonia. [ 10 ] [ 5 ] The germ cells are bipotential in that prior to migrating to the gonads, they are capable of forming either spermatogonia or oogonia.
The gonadal ridge produces the steroidogenic cells for both the gonads and the adrenal cortex. [4] The adrenal medulla is derived from ectodermal cells. Cells that will become adrenal tissue move retroperitoneally to the upper portion of the mesonephros.
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 connective tissue cells (pre-granulosa cells). In this way, the rudiments of the ovarian follicles are formed.
2 and 5 sex cords A depiction of the migration of the cells which will give rise to the sex cords into the genital ridge where they will become the gonads of the embryo. Sex cords are embryonic structures which eventually will give rise (differentiate) to the adult gonads (reproductive organs). [1]
Germ cells migrating to the gonads may not reach that intended destination and a tumor can grow wherever they end up, but the exact cause is still unknown. These tumors can be benign or malignant. [23] On arrival at the gonad, primordial germ cells that do not properly differentiate may produce germ cell tumors of the ovary or testis in a mouse ...