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Germ cells are specified early in development [4] and can only differentiate into gametes. [5] The segregation of germ cells is often determined by the species, with some undergoing preformation, where the germ cells are determined by maternally inherited factors before or immediately after fertilisation, and others undergoing epigenesis, where the germ cell lineage is determined from ...
The specification of gonocytes to be confined to male germ cells occurred after foundational differences between the mechanisms of male and female fetal germ cells were uncovered. Some scientists prefer the terms “prospermatogonia” and “prespermatogonia” for their functional clarity.
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 ...
Cleavage in most animals segregates cells containing germ plasm from other cells. The germ plasm effectively turns off gene expression to render the genome of the cell inert. Cells expressing germ plasm become primordial germ cells (PGCs) which will then give rise to the gametes. The germ line development in mammals, on the other hand, occurs ...
Somatic cells are more commonly used for genetic analysis because they are easier to obtain than gametes. If the disease is a result of pure germline mosaicism, then the disease causing mutant allele would never be present in the somatic cells. This is a source of uncertainty for genetic counselling. An individual may still be a carrier for a ...
The gonadal ridge, in turn, develops into a gonad. This is a testis in the male and an ovary in the female. At first, the mesonephros and gonadal ridge are continuous, but as the embryo grows the gonadal ridge gradually becomes pinched off from the mesonephros. However, some cells of mesonephric origin join the gonadal ridge.
After female (XX) germ cells collect in the undifferentiated gonads, the up-regulation of Stra8 is required for germ cell differentiation into an oogonium and eventually enter meiosis. One major factor that contributes to the up-regulation of Stra8 , is the initiation of the β-Catenin signaling pathway via RSPO1, which is also responsible for ...
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]