Search results
Results from the WOW.Com Content Network
Germ cells produce gametes and are the only cells that can undergo meiosis as well as mitosis. Somatic cells are all the other cells that form the building blocks of the body and they only divide by mitosis. The lineage of germ cells is called the germline. Germ cell specification begins during cleavage in many animals or in the epiblast during ...
Human embryonic development or human embryogenesis is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled ...
A spermatogonium (pl.: spermatogonia) is an undifferentiated male germ cell. Spermatogonia undergo spermatogenesis to form mature spermatozoa in the seminiferous tubules of the testis. There are three subtypes of spermatogonia in humans: Type A (dark) cells, with dark nuclei. These cells are reserve spermatogonial stem cells which do not ...
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testicle. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. [ 1 ] These cells are called spermatogonial stem cells. The mitotic division of these produces two ...
A germ layer is a primary layer of cells that forms during embryonic development. [ 1 ] The three germ layers in vertebrates are particularly pronounced; however, all eumetazoans (animals that are sister taxa to the sponges) produce two or three primary germ layers.
The bilaminar embryonic disc, bilaminar blastoderm or embryonic disc is the distinct two-layered structure of cells formed in an embryo. In the development of the human embryo this takes place by day eight. It is formed when the inner cell mass, also known as the embryoblast, forms a bilaminar disc of two layers, an upper layer called the ...
Contents. Germline. In biology and genetics, the germline is the population of a multicellular organism 's cells that develop into germ cells. In other words, they are the cells that form gametes (eggs and sperm), which can come together to form a zygote. They differentiate in the gonads from primordial germ cells into gametogonia, which ...
Germline development in mammals. Mammalian PGCs are specified by signalling between cells (induction), rather than by the segregation of germ plasm as the embryo divides. [6] In mice, PGCs originate from the proximal epiblast, close to the extra-embryonic ectoderm (ExE), of the post-implantation embryo as early as embryonic day 6.5. [7]