Sperm cell

Ectocarpene is a volatile sperm cell attracting matenal released by the eggs of the seaweed Ectocarpus siliculosus Its constitution is... 

Multifidene is a sperm cell attracting substance released by the female of a species of brown algae Cutlena rnultifida) The constitution of multifidene is... 

As already noted, microtubules are also the fundamental building blocks of cilia and flagella. Cilia are short, cylindrical, hairlike projections on the surfaces of the cells of many animals and lower plants. The beating motion of cilia functions either to move cells from place to place or to facilitate the movement of extracellular fluid over the cell surface. Flagella are much longer structures found singly or a few at a time on certain cells (such as sperm cells). They pro-... 

Some specialized eukaryotic cells have cilia that show a whiplike motion. Sperm cells move with one flagella, which is much longer than a cilium but has a nearly identical internal structure called axoneme. It is composed of nine doublet MTs that form a ring around a pair of single MTs. Numerous proteins bind to the MTs. Ciliary dynein motors generate the force by which MTs slide along each other to cause the bending of the axoneme necessary for motion. 

In mammals, ciliated cells line the respiratory air passages, the fallopian tubes, and the ventricles of the brain. The cilia beat in a coordinated manner in waves that propel fluids, suspended cells, and small particles along a surface. The motility of the sperm cell is provided by a single flagellum. 

Kubiak Is the demethylase active specifically in the sperm cell cycle ... 

The major FSH target in the male is the Sertoli cells, found in the walls of the seminiferous tubules of the testis. They function to anchor and nourish the spermatids, which subsequently are transformed into spermatozoa during the process of spermatogenesis. Sertoli cells also produce inhibin (discussed later), which functions as a negative feedback regulator of FSH. The major physiological effect of FSH in the male is thus sperm cell production. 

Gonadotrophins are also used in assisted reproduction procedures. Here the aim is to administer therapeutic doses of FSH that exceed individual follicular FSH threshold requirements, thus stimulating multiple follicular growth. This, in turn, facilitates harvest of multiple eggs, which are then available for in vitro fertilization. This technique is often employed when a woman has a blocked fallopian tube or some other impediment to normal fertilization of the egg by a sperm cell. After treatment, the resultant eggs are collected, incubated in vitro with her partner s sperm, incubated in culture media until the embryonic blastocyst is formed, and then implanted into the mother s uterus. 

Spermicides, most of which contain nonoxynol-9, are surfactants that destroy sperm cell walls. They offer no protection against STDs, and when... 

There are two types of cell division mitosis and meiosis. Most of the time when people refer to "cell division," they mean mitosis, the process of making new body cells. Meiosis is the type of cell division that creates egg and sperm cells. 

Gene mutations occur in two ways they can be inherited from a parent or acquired during a person s lifetime. Mutations that are passed from parent to child are called hereditary mutations or germline mutations (because they are present in the egg and sperm cells, which are also called germ cells). This type of mutation is present throughout a person s life in virtually every cell in the body. 

Mutations that occur only in an egg or sperm cell, or those that occur just after fertilization, are called new (de novo) mutations. De novo mutations may explain genetic disorders in which an affected child has a mutation in every cell, but has no family history of the disorder. 

Chromosomal disorders can also be caused by changes in chromosome structure. These changes are caused by the breakage and reunion of chromosome segments when an egg or sperm cell is formed or in early fetal development. Pieces of DNA can be rearranged within one chromosome, or transferred between two or more chromosomes. The effects of structural changes depend on their size and location. Many different structural changes are possible some cause medical problems, while others may have no effect on a person s health. 

Uniparental disomy (UPD) occurs when a person receives two copies of a chromosome, or part of a chromosome, from one parent and no copies from the other parent. UPD can occur as a random event during the formation of egg or sperm cells or may happen in early fetal development. 

Reproductive cells Egg and sperm cells. Each mature reproductive cell carries a single set of 23 chromosomes. [NIH]... 

Angiotensin converting enzyme (ACE) is an important enzyme for the regulation of blood pressure, ft exists in two forms the somatic form has 1277 amino acids, while the sperm cell form has 701 amino acids. The somatic form consists of two domains the carboxy-terminal (C) domain and the amino-terminal (N) domain. The sperm cell form consists of only the C domain. Studies have shown that the C domain is the dominant angiotensin converting site for controlling blood pressure and cardiovascular functions. 

As would be expected, khat overuse produces symptoms similar to those of other monoamine stimulants, such as cocaine or amphetamine, including signs of sympathetic overarousal. In the extreme this can involve a toxic psychosis. Disorders more frequently associated with chronic khat use in males are headaches, anorexia, insomnia, constipation, and respiratory illnesses (Kennedy et al. 1983). Females report higher incidences of acute gastritis, jaundice, bronchitis and hepatic diseases. Also, cathinone has toxic reproductive effects in humans and experimental animals (Islam et al. 1990). It decreases sperm count and motility, and increases the number of abnormal sperm cells. It also decreases plasma testosterone in rats. 

Because a sperm cell contributes no mitochondria to the e cell during fertilization, mitochondrial DNA is inherited exclusively through females. Ped rees for mitochondrial diseases thus display a distinct mode of inheritance diseases are transmitted only from affected females to their offspring (Pig II-l-l 1). 

Triploidy refers to cells that contain three copies of each chromosome (69 total). THploidy, which usually occurs as a result of the fertilization of an ovum by two sperm cells, is common at conception, but the vast majority of these conceptions are lost prenatally. However, about 1 in 10,000 live births is a triploid. These babies have multiple defects of the heart and central nervous system, and they do not survive. 

Brain, muscle, and kidney cells, for example, all possess a few hundred or a few thousand mitochondria per cell. The human egg cell is remarkable in that it contains about 100,000 mitochondria. A sperm cell, in contrast, contains fewer than 100. New mitochondria are made as cells divide. The synthesis of new mitochondria requires that the proteins coded for by the nuclear genome and those coded for by the mitochondrial genome be mutually compatible to ensure optimal mitochondrial function. Since we can experience mutations in both nuclear and mitochondrial DNA, leading to alterations in mitochondrial proteins, long-term compatibility... 

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