Hook protein: HOOK is a family of evolutionarily related proteins.Spermiogenesis: Spermiogenesis is the final stage of spermatogenesis, which sees the maturation of spermatids into mature, motile spermatozoa. The spermatid is more or less circular cell containing a nucleus, Golgi apparatus, centriole and mitochondria.Hyperactivation: Hyperactivation is a type of sperm motility. Hyperactivated sperm motility is characterised by a high amplitude, asymmetrical beating pattern of the sperm tail (flagellum).Spermatid: The spermatid is the haploid male gametid that results from division of secondary spermatocytes. As a result of meiosis, each spermatid contains only half of the genetic material present in the original primary spermatocyte.Sperm: Sperm is the male reproductive cell and is derived from the Greek word (σπέρμα) sperma (meaning "seed"). In the types of sexual reproduction known as anisogamy and its subtype oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell.Blood–testis barrier: The blood–testis barrier is a physical barrier between the blood vessels and the seminiferous tubules of the animal testes. The name "blood-testis barrier" is misleading in that it is not a blood-organ barrier in a strict sense, but is formed between Sertoli cells of the seminiferous tubule and as such isolates the further developed stages of germ cells from the blood.CAP protein family: In molecular biology, the CAP protein family (cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins (CAP)) is a large family of proteins that are found in a wide range of organisms, including prokaryotes and non-vertebrate eukaryotes. The nine subfamilies of the mammalian CAP 'super'family include: the human glioma pathogenesis-related 1 (GLIPR1), Golgi associated pathogenesis related-1 (GAPR1) proteins, peptidase inhibitor 15 (PI15), peptidase inhibitor 16 (PI16), cysteine-rich secretory proteins (CRISPs), CRISP LCCL domain containing 1 (CRISPLD1), CRISP LCCL domain containing 2 (CRISPLD2), mannose receptor like and the R3H domain containing like proteins.Male infertilityEpididymis: The epididymis (; plural: epididymides or ) is a tube that connects a testicle to a vas deferens in the male reproductive system. It is present in all male reptiles, birds, and mammals.Postcoital test: The postcoital test (PCT) (also known as Sims test, Huhner test or Sims-Huhner test) is a test in the evaluation of infertility. The test examines interaction between sperm and mucus of the cervix.CD155: CD155 (cluster of differentiation 155) also known as the poliovirus receptor is a protein that in humans is encoded by the PVR gene.Low Fertility Cohorts Study: The Low Fertility Cohorts Study, 1978: A Survey of White, Ever-Married Women Belonging to the 1901-1910 United States Birth Cohorts,Data Sharing For Demographic Research consists of personal interviews of white, ever-married women born between July 1, 1900, and June 30, 1910. In 1978, a national survey of 1,049 married women between the ages of 68 and 78 were interviewed between the months of March and July in order to investigate low fertility during the 1920s and 1930s and the women of childbearing age during those decades.Low-voltage electron microscope: Low-voltage electron microscope (LVEM) is an electron microscope which operates at accelerating voltages of a few kiloelectronvolts or less. While the low voltage electron microscopy technique will never replace conventional high voltage electron microscopes, it is quickly becoming appreciated for many different disciplines.Sea urchin injury: Sea urchin injuries are caused by contact with sea urchins, and are characterized by puncture wounds inflicted by the animal's brittle, fragile spines.Reproductive technology: Reproductive technology (RT) encompasses all current and anticipated uses of technology in human and animal reproduction, including assisted reproductive technology, contraception and others.Janin PlotColes PhillipsAcrosome: The acrosome is an organelle that develops over the anterior half of the head in the spermatozoa (sperm cells) of many animals. It is a cap-like structure derived from the Golgi apparatus.Protein primary structure: The primary structure of a peptide or protein is the linear sequence of its amino acid structural units, and partly comprises its overall biomolecular structure. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end.Flagellar motor switch: In molecular biology, the flagellar motor switch is a protein complex. In Escherichia coli and Salmonella typhimurium it regulates the direction of flagellar rotation and hence controls swimming behaviour.Semen quality: Semen quality is a measure of the ability of semen to accomplish fertilization. Thus, it is a measure of fertility in a man.Screening of potential sperm bank donors: In sperm banks, screening of potential sperm donors typically includes genetic diseases, chromosomal abnormalities and sexually transmitted infections that may be transmitted through sperm. The screening procedure generally also includes a quarantine period, in which the samples are frozen and stored for at least 6 months after which the donor will be re-tested for the STIs.Microtubule: Microtubules ([+ tube] + [are a component of the [[cytoskeleton], found throughout the [[cytoplasm. These tubular polymers of tubulin can grow as long as 50 micrometres and are highly dynamic.Lattice protein: Lattice proteins are highly simplified computer models of proteins which are used to investigate protein folding.Metachronal rhythm: A metachronal rhythm or metachronal wave refers to wavy movements produced by the sequential action (as opposed to synchronized) of structures such as cilia, segments of worms or legs. These movements produce the appearance of a travelling wave.Heat shock protein: Heat shock proteins (HSP) are a family of proteins that are produced by cells in response to exposure to stressful conditions. They were first described in relation to heat shock, but are now known to also be expressed during other stresses including exposure to cold, UV light, and during wound healing or tissue remodeling..Gastrocopta pellucida: Gastrocopta pellucida is a species of minute air-breathing land snail, a terrestrial pulmonate gastropod mollusk or micromollusk in the family Vertiginidae, the vertigo snails.Symmetry element: A symmetry element is a point of reference about which symmetry operations can take place. In particular, symmetry elements can be centers of inversion, axes of rotation and mirror planes.Retrograde ejaculation