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A B C D E F G H I K L M N O P R S T U V W Y Z

A Pap smear is a method to screen for cervical cancer. Squamous cells (flat, scale-like cells) are obtained from the outer surface of the cervix as well as columnar cells (tall, thin cells) from the inner canal leading to the uterus. The junction where these two cell types meet is called the transformation zone and is where most cell abnormalities are found.

Parthenotes are the products of parthenogenesis, the process in which eggs become activated to begin dividing without fertilization. Parthenotes contain genetic material from only the maternal source. In contrast, embryos are created through fertilization and contain genetic material from two genetically distinct cells. No viable human parthenote has been reported.

With regard to oncofertility, the patient navigator is a medical professional that provides female and male cancer patients with information about their fertility preservation options and helps to coordinate their care.

The pelvis is the basin-shaped structure of the vertebrate skeleton that supports the upper torso and spine and protects the rectum, bladder, and reproductive organs.

The penis is the external male sex organ. It functions in urine output and is also responsible for the delivery of sperm to the female tract during sexual intercourse.

Perimenopause, also called the "menopausal transition," is the time frame in which a woman's body shifts from regular cycles of ovulation and menstruation to menopausal symptoms, including hot flashes, vaginal dryness, night sweats, absence of menstruation, and permanent infertility. This period typically begins when women reach their 40s, though symptoms can be detected earlier.

Perinatal refers to the period around the time of birth – either directly before or after.

In females, the perineum is the area between the vagina and anus, and in males, it is the area between the scrotum and anus. The perineum is considered to be an erogenous zone in both sexes, and the female perineum is highly susceptible to damage during childbirth.

PGD

A pharmacological chaperone (or pharmacoperone from "protein chaperone") is a small molecule that enters cells and serves as a molecular scaffolding in order to cause otherwise-misfolded mutant proteins to fold and route correctly within the cell. Mutation of proteins often causes molecular misfolding, which results in protein misrouting within the cell. Accordingly, mutant molecules may retain proper function but end up in parts of the cell where the function is inappropriate, or even deleterious, to cell function. Misfolded proteins are usually recognized by the quality-control system of the cell and retained (and often destroyed or recycled) in the endoplasmic reticulum. Pharmacoperones correct the folding of misfolded proteins, allowing them to pass through the cell's quality-control system and become correctly routed. Since mutations often cause disease by causing misfolding and misrouting, pharmacoperones are potentially therapeutic agents, since they are able to correct this defect.

 

Ref.: Conn, P.M. and Janovick, J.A., A New Understanding of Protein Mutation Unfolds, American Scientist 93:314-321, 2005.

The pituitary gland is a very small organ, located at the base of the brain, which produces and releases hormones (signals) that control other organs and body processes. The pituitary gland responds to signals from the hypothalamus. The anterior pituitary gland is the front portion of the pituitary gland, and it secretes hormones that control physiological processes including growth, reproduction, and stress. The posterior pituitary gland is behind the anterior portion and secretes hormones involved with water balance and uterine contractions during labor.

The placenta is an organ that connects the fetus to a woman’s uterus during pregnancy. It functions in nutrient uptake, waste elimination, and gas exchange in supporting the growth of the fetus.

PMS
POF

A polar body is the product of asymmetric cell division that occurs during meiosis. Both phases of meiosis produce a polar body, and the final result of completed meiosis is two polar bodies and one haploid egg. The formation of polar bodies allows the DNA content of the egg to be reduced while still maintaining critical stores of maternal components in the egg that are important for supporting future fertilization and pre-implantation embryo development.

Polycystic ovary syndrome is a common hormonal disorder that affects many women of reproductive age. The name of the disorder came from the observation that women with PCOS often have the appearance of “cysts” along the outer edge of their ovaries when viewed by ultrasound. These “cysts” correspond to immature follicles that have stopped developing due to hormonal imbalance. Polycystic ovaries develop as a consequence of excess ovarian androgen. PCOS can disrupt ovulation or stop it altogether, often leading to subfertility. Women with PCOS may experience excessive hair growth, weight gain, acne, and many other symptoms, ranging from mild to severe.

Polyhydramnios is the accumulation of excess amniotic fluid in the amniotic sac during pregnancy. This may be treated, if severe, by the withdrawal of amniotic fluid. Polyhydramnios can cause pre-term labor and various symptoms in the mother (e.g. shortness of breath).

A polymer is a large molecule composed of repeating structural units. Polymers may be natural (e.g. DNA or alginate) or be synthetic (e.g. plastics).

Polyploidy occurs when a cell or an organism has more than two sets of homologous chromosomes. This can be the result of failure to undergo nuclear division after DNA replication. Polyploidy differs from aneuploidy in that aneuploidy refers to when a cell or an organism has too few or too many chromosomes.

Polyspermy occurs when more than one sperm enters the egg during fertilization. Polyspermy results in a zygote that contains too much DNA (polyploidy) and that is often non-viable. During normal fertilization, the egg has several mechanisms to prevent this from occurring, including the block to polyspermy established by the zona pellucida.

A positive feedback mechanism is a model in which the behavior of the system grows/amplifies through self-activation.

Post-implantation refers to the time of embryo development that occurs after implantation in the uterus has occurred.

Postmenopause refers to the time period after menopause.

Postnatal refers to occurrences after giving birth.

An ovarian follicle that has no antrum during folliculogenesis. Most growing follicles at the early stages of folliculogenesis are preantral follicles. Preantral follicles consist of ocytes, granulosa cells, and theca cells, which grow and mature during folliculogenesis. 

Preeclampsia is a pregnancy specific condition that usually develops in the late second or third trimester. It is marked by the onset of hypertension and excess protein in the woman’s urine. If left untreated, preeclampsia can lead to serious health complications for both the mother and fetus.

In humans, pregnancy refers to the development of offspring (either a single offspring or multiple) in the uterus of a woman in preparation for the birth of independent human life.

Preimplantation refers to the time of embryo development that occurs prior to implantation in the uterus.

Preimplantation genetic diagnosis (PGD) is an ART procedure in which genetic testing is done on biopsied cell(s) from a preimplantation-stage embryo. With this technology, only unaffected embryos are transferred back to the recipient uterus to initiate a pregnancy. PGD was originally developed to screen for single gene disorders but is currently used to detect different factors, including HLA-type, chromosome abnormalities, and aneuploidy. Genetic testing can be done on biopsies of the first or second polar bodies, a single blastomere from a cleavage-stage embryo, or several trophectoderm cells from a blastocyst.

Premature menopause is menopause that happens early, before the age of 40. It can be the result of medical treatments, genetic issues, or it can occur naturally.

Premature ovarian failure (POF) is also referred to as premature menopause or primary ovarian insufficiency, and it is characterized by the inability to ovulate and an early loss of function of the ovaries altogether due to a lack of or no follicles in the ovary in women who are under the age of 40 (prior to the typical onset of menopause). POF leads to subfertility or infertility and is also linked to osteoporosis and other autoimmune disorders. It can be a result of genetic abnormalities, removal of the ovaries, or prior radiation therapy or chemotherapy. Premature ovarian failure differs from menopause in that women with premature ovarian failure may have occasional or irregular periods and may possibly become pregnant.

Premenstrual syndrome refers to symptoms that might occur between the time of ovulation and menstrual bleeding. These symptoms can include bloating, mood swings, cramping, headaches, etc.

Prenatal refers to occurrences during pregnancy (before giving birth).

The prepuce (often referred to as "foreskin" in males and the "clitoral hood" in females) is a piece of retractable skin. In uncircumcised males, it covers and protects the glans penis when the penis is not erect. In females, it covers and protects the glans clitoris.

The primary germ layers are the ectoderm, mesoderm, and endoderm. Primordial germ cells are typically considered distinct from primary germ layers, although all are derived from the inner cell mass of the embryo.

A primary ovarian follicle is an immature follicle consisting of an oocyte surrounded by a single layer of tall, supporting granulosa cells.

The primordial follicle is the most immature stage of an ovarian follicle’s development. The primordial follicle consists of an oocyte surrounded by a single layer of flat, supporting granulosa cells.

PRL

Progesterone is a steroid hormone released by the corpus luteum and placenta that prepares the uterus to receive and support a fertilized egg. It is the predominant hormone secreted during the luteal phase of the menstrual cycle and is essential in establishing and maintaining a pregnancy. 

Progestin is any natural or synthetic substance, which has some or all of the biological effects of progesterone.

Prolactin (PRL) is a hormone released by the pituitary gland. It primarily acts on the mammary gland to initiate and maintain milk production after pregnancy.

The pronucleus is the nucleus of either the sperm or the egg that develops after fertilization. Following fertilization and completion of meiosis II, the egg’s DNA will decondense, and the female pronucleus will form. Similarly, the sperm DNA will also decondense and the male pronucleus will form. In many species, the male pronucleus is larger than the female one. A diploid zygote will be produced when the haploid male and female pronuclei fuse just prior to the first mitotic division.

Prophase is a phase of cell division during which DNA is packaged and condensed into chromosomes.

The prostate gland is a large gland in the male reproductive system that sits just below the bladder. It functions in the control of urination and secretes a fluid that is a component of semen.

Prostate specific antigen (PSA) is a protein produced by the prostate which facilitates sperm motility in semen. It is used as a biomarker to detect prostate enlargement or prostate cancer.   

A protein is a molecule comprised of many amino acids in a linear array; proteins accomplish the major functions that cells carry out (metabolism, production of specialized molecules, and their self-reproduction by mitosis).

PSA

Puberty is the period of human development during which young people become capable of sexual reproduction. Puberty is marked by physiological changes, such as the development of secondary sex characteristics (e.g. breast development in females and facial hair in males) and the maturation of genital organs. It generally occurs between the ages of 10 and 14 in girls and 11 and 16 in boys.