By What is the difference between primordial germ cells and spermatogonia?
Indeed, the functional characteristics of the surrounding somatic cells of the gonads regulate germ cell sexual differentiation. In the fetal testis, primordial germ cells differentiate to gonocytes, which proliferate by mitosis but do not enter meiosis as in the fetal ovary.
Is spermatogonia a primordial germ cell?
Primordial germ cells (PGCs) are derived from a population of pluripotent epiblast cells in mice. Thus, fetal male germ cell development is remarkably flexible, and the maturation process, from epiblast cells through PGCs to postnatal spermatogonia, can occur in the postnatal testicular environment.
What do primordial germ cells arise from?
In many animals, the germ cells originate in the primitive streak and migrate via the gut of an embryo to the developing gonads. There, they undergo meiosis, followed by cellular differentiation into mature gametes, either eggs or sperm. Unlike animals, plants do not have germ cells designated in early development.
Where do primordial germ cells migrate to?
Primordial germ cells (PGCs), precursors to sperm and eggs, have to migrate across the embryo to reach somatic gonadal precursors, where they carry out their function. Studies of model organisms have revealed that, despite important differences, several features of PGC migration are conserved.
What are primordial germ cells called?
In humans, the primordial germ cell (PGC) is the primary undifferentiated stem cell type that will differentiate towards gametes: spermatozoa or oocytes.
What hormone initiates sperm?
Male Hormones The onset of puberty is controlled by two major hormones: FSH initiates spermatogenesis and LH signals the release of testosterone.
Are gonads germ cells?
These primordial germ cells migrate to the developing gonads, which will form the ovaries in females and the testes in males. After a period of mitotic proliferation, the primordial germ cells undergo meiosis and differentiate into mature gametes—either eggs or sperm.
What is germ cell determination?
In most animal species, the determination of the primordial germ cells is brought about by the cytoplasmic localization of specific proteins and mRNAs in certain cells of the early embryo (mammals being a major exception to this general rule). These cytoplasmic components are referred to as the germ plasm.
What is a epiblast?
The epiblast is the outermost layer of the embryonic disc during the early embryonic development. The cells of the embryoblast grow and form the embryonic disc. The outer layer of the embryonic disc is called the epiblast whereas the layer below the epiblast is referred to as the hypoblast.
What is the negative feedback loop for sperm?
A negative feedback system occurs in the male with rising levels of testosterone acting on the hypothalamus and anterior pituitary to inhibit the release of GnRH, FSH, and LH. The Sertoli cells produce the hormone inhibin, which is released into the blood when the sperm count is too high.
What hormone is secreted by the hypothalamus?
Hormones and the Endocrine System
| Where the hormone is produced | Hormone(s) secreted |
|---|---|
| Hypothalamus | Growth hormone releasing hormone (GHRH) |
| Hypothalamus | Thyrotropin releasing hormone (TRH) |
| Hypothalamus | Gonadotropin releasing hormone (GnRH) |
| Hypothalamus | Corticotropin releasing hormone (CRH) |