SpermSperm (pl.: sperm or sperms) is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Sperm cells contribute approximately half of the nuclear genetic information to the diploid offspring (excluding, in most cases, mitochondrial DNA).
SpermiogenesisSpermiogenesis is the final stage of spermatogenesis, during which the spermatids develop into mature spermatozoa. At the beginning of the stage, the spermatid is a more or less circular cell containing a nucleus, Golgi apparatus, centriole and mitochondria; by the end of the process, it has radically transformed into an elongated spermatozoon, complete with a head, midpiece, and tail.MeiosisMeiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes: the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one copy of each chromosome (haploid). Additionally, prior to the division, genetic material from the paternal and maternal copies of each chromosome is crossed over, creating new combinations of code on each chromosome.
ProtamineProtamines are small, arginine-rich, nuclearproteins that replace histones late in the haploid phase of spermatogenesis and are believed essential for sperm head condensation via genomic DNA compaction and stabilization. They may allow for denser packaging of DNA in the spermatozoon than histones, but they must be decompressed before the genetic data can be used for protein synthesis.
SpermatocyteSpermatocytes are a type of male gametocyte in animals. They derive from immature germ cells called spermatogonia. They are found in the testis, in a structure known as the seminiferous tubules. There are two types of spermatocytes, primary and secondary spermatocytes. Primary and secondary spermatocytes are formed through the process of spermatocytogenesis. Primary spermatocytes are diploid (2N) cells. After meiosis I, two secondary spermatocytes are formed.
PloidyPloidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomalgenes. Here sets of chromosomes refers to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair—the form in which chromosomes naturally exist.
AcrosomeThe acrosome is an organelle that develops over the anterior (front) half of the head in the spermatozoa (sperm cells) of humans and many other animals. It is a cap-like structure derived from the Golgi apparatus. In placental mammals, the acrosome contains degradative enzymes (including hyaluronidase and acrosin).GametidA gametid is a complementary gamete to the gamete that gives rise to a zygote after conception. During meiosis, four gametes, or haploid cells, are the products of diploid cell division. Two gametes, one egg and one sperm, unite during conception, yielding a zygote. For each gamete that makes a zygote, there is a complementary gamete, or gametid. There are gametids for both egg and sperm gametes. Another word for a gametid is a nontransmitted gamete.ChromatinChromatin is a complex of DNA and protein responsible for condensing and packaging chromosomal DNA. Chromatin is found in both bacterial and eukaryotic cells. Eukaryotic chromatin consists primarily of DNA associated with histone proteins and numerous other chromatin-binding factors that contribute to genome organization and regulation.
MitochondriaOrganelle in eukaryotic cells responsible for respirationA mitochondrion (pl. mitochondria) is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. They were discovered by Albert von Kölliker in 1857 in the voluntary muscles of insects.
Nanjing Medical UniversityNanjing Medical University (NJMU; 南京医科大学) is a provincial public university in Nanjing, Jiangsu, China. It is affiliated with the Province of Jiangsu. The university is part of the Double First-Class Construction. The school was originally established in 1934 in Zhenjiang, but subsequently relocated to Nanjing in 1957. The university has two main campuses: Wutai and Jiangning, both of which have international student apartments.
Stem cellUnspecialized biological cell that can become specializedIn multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can change into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage. They are found in both embryonic and adult organisms, but they have slightly different properties in each.*As an Amazon Associate I earn from qualifying purchases.