BIOL 1040 - Chapter 27

Reproduction and Embryonic Development; BIOL 1040 (General Biology II) - Exam 3

Reproduction

The creation of new individuals from existing ones.

Asexual Reproduction

The creation of genetically identical offspring by a single parent, without the participation of sperm and egg.

Sexual Reproduction

The creation of genetically unique offspring by the fusion of two haploid sex cells (gametes), forming a diploid zygote.

Fertilization

The union of the nucleus of a sperm cell with the nucleus of an egg cell, producing a zygote.

Gametes

A sex cell; a haploid egg or sperm. The union of two of opposite sex produces a zygote.

Sperm

A male gamete.

Egg

A female gamete.

Zygote

The diploid fertilized egg, which results from the union of a sperm cell nucleus and an egg cell nucleus.

Hermaphroditism

A condition in which an individual has both female and male gonads and functions as both a male and female in sexual reproduction by producing both sperm and eggs.

Internal Fertilization

Reproduction in which sperm are typically deposited in or near the female reproductive tract and fertilization occurs within the tract.

Gonad

A sex organ in an animal that secretes sex hormones and produces gametes; an ovary or testis.

Ovary

The female gonad, which produces egg cells and reproductive hormones.

Follicle

A cluster of cells in the ovary that includes a developing egg and cells that surround, protect, and nourish it. Follicles secret the hormone estrogen.

Ovulation

The release of an egg cell from an ovarian follicle.

Corpus Luteum

A small body of endocrine tissue that develops from an ovarian follicle after ovulation and secretes progesterone and estrogen during pregnancy.

Oviduct

The tube that conveys egg cells away from an ovary; also called a fallopian tube. In humans, it is the normal site of fertilization.

Uterus

In the reproductive system of a mammalian female, the organ where the development of young occurs; the womb.

Endometrium

The inner lining of the uterus in mammals, richly supplied with blood vessels that provide the maternal part of the placenta and nourish the developing embryo.

Embryo

A developing stage of a multicellular organism. In humans, the stage in development from the first division of the zygote until body structures begin to appear, about the 9th week of gestation.

Fetus

A developing human from the 9th week of gestation until birth. The fetus has all the major structures of an adult.

Ectopic Pregnancy

The implantation and development of an embryo outside the uterus.

Cervix

The neck of the uterus, which opens into the vagina.

Vagina

Part of the female reproductive system between the uterus and the outside opening; the birth canal in mammals; also accommodates the male’s penis and receives sperm during copulation.

Vulva

The collective term for the external female genitalia.

Labia Minora

A pair of inner folds of skin, bordering and protecting the female genital region.

Labia Majora

A pair of outer thickened folds of the skin that protect the female genital region.

Clitoris

An organ in the female that engorges with blood and becomes erect during sexual arousal.

Testis

The male gonad in an animal. Produces sperm, and in many species, reproductive hormones.

Scrotum

A pouch of skin outside the abdomen that houses a testis and functions in cooling sperm, keeping them viable.

Testicle

A testis and scrotum together.

Epididymis

A long coiled tube into which sperm pass from the testis and are stored until mature and ejaculated.

Ejaculation

The expulsion of semen from the penis.

Vas Deferens

Part of the male reproductive system that conveys sperm away from the testis; the sperm duct; in humans, the tube that conveys sperm between the epididymis and the common duct that leads to the urethra.

Seminal Vesicle

A gland in males that secretes a thick fluid that contains fructose, which provides most of the sperm’s energy

Prostate Gland

A gland in human males that secretes a thin fluid that nourishes the sperm.

Bulbourethral Gland

One pair of glands near the base of the penis in the human male that secrete a clear alkaline mucus.

Semen

The sperm-containing fluid that is ejaculated by the male during orgasm.

Penis

The copulatory structure of male mammals.

Impotence

The inability to maintain and erection; also called erectile dysfunction.

Gametogenesis

The creation of gametes within the gonads.

Spermatogenesis

The formation of sperm cells.

Oogenesis

The development of mature egg cells.

Reproductive Cycle

A recurring sequence of events that produces eggs, makes them available for fertilization, and prepares the female body for pregnancy.

Ovarian Cycle

Hormonally synchronized cyclic events in the mammalian ovary, culminating in ovulation.

Menstrual Cycle

The hormonally synchronized cyclic buildup and breakdown of the endometrium of some primates, including humans.

Menstruation

Uterine bleeding resulting from shedding of the endometrium during a menstrual cycle.

Contraception

The deliberate prevention of pregnancy.

Oral Contraceptive

A chemical contraceptive that contains synthetic estrogen and/or progesterone (or a synthetic progesterone-like hormone called progestin) and prevents the release of eggs. Also called a birth control pill.

Sexually Transmitted Infection (STI)

A pathogen spread by sexual contact. If symptoms are present, then the person is said to have sexually transmitted disease (STD).

Chlamydia

A member of a group of bacteria that live inside eukaryotic host cells; a common sexually transmitted disease caused by the bacterium Chlamydia trachomatis.

Genital Herpes

A sexually transmitted disease caused by the herpes simplex virus type 2.

Tubal Ligation

A means of sterilization in which a segment of each of a woman’s two oviducts is removed. The ends of the tubes are then tied closed to prevent eggs from reaching the uterus (commonly referred to as having the “tubes tied”).

Vasectomy

Surgical removal of a section of the two sperm ducts (vasa deferentia) to prevent sperm from reaching the urethra; a means of sterilization in males.

Intrauterine Device (IUD)

A T-shaped device that, when placed within the uterus, acts as a female contraception.

Condom

A form of contraception; a sheath that fits over the penis to prevent the transfer of sperm to the vagina.

Spermicide

A sperm-killing chemical (cream, jelly, or foam) that works with a barrier device as a method of contraception.

Morning After Pill (MAP)

A birth control pill taken within three days of unprotected intercourse to prevent fertilization or implantation.

Acrosome

A membrane-enclosed sac at the tip of a sperm. Contains enzymes that help the sperm penetrate and egg.

Cleavage

In animal development, the first major phase of embryonic development, in which rapid cell divisions without cell growth transforms the animal zygote into a ball of cells.

Blastula

An embryonic stage that marks the end of cleavage during animal development; a hollow ball of cells in many species.

Gastrulation

The second major phase of embryonic development, which transforms the blastula into a gastrula. Adds more cells to the embryo and sort the cells into distinct cell layers.

Gastrula

The embryonic stage resulting from gastrulation in animal development. Most have three layers of cells: ectoderm, endoderm, and mesoderm.

Endoderm

The innermost of three embryonic cell layers in gastrula; gives rise to the innermost linings of the digestive tract and other hollow organs in the adult.

Ectoderm

The outer layer of three embryonic cell layers in a gastrula. Forms the skin of the gastrula and give rise to the epidermis and nervous system in the adult.

Mesoderm

The middle layer of the three embryonic cell layers in a gastrula. Gives rise to muscles, bones, the dermis of the skin, and most other organs in the adult.

Notochord

A flexible, cartilage-like, longitudinal rod located between the digestive tract and nerve cord in chordate animals; present only in embryos in many species.

Neural Tube

An embryonic cylinder that develops from the ectoderm after gastrulation and give rise to the brain and spinal cord.

Coelom

A body cavity completely lined with mesoderm.

Induction

During embryonic development, the influence of one group of cells on an adjacent group of cells.

Apoptosis

The timely and tidy suicide of cells; also called programmed cell death.

Homeotic Gene

A master control gene that determine the identity of a body structure of a developing organism, presumably by controlling the developmental fate of groups of cells.

Homeobox

A 180-nucleotide sequence within a homeotic gene and some other developmental genes.

Gestation

Pregnancy; the state of carrying developing young within the female reproductive tract.

Conception

The fertilization of the egg by a sperm cell in humans.

Blastocyst

A mammalian embryo made up of a hollow ball of cells that results from cleavage and that implants in the mother’s endometrium.

Placenta

In most mammals, the organ that provides nutrients and oxygen to the embryo and helps dispose of its metabolic wastes; formed of the embryo’s chorion and the mother’s endometrial blood vessels.

Extraembryonic Membranes

Four membranes (the yolk sac, amnion, chorion, and allantois) that form a life-support system for the developing embryo of a reptile, bird, or mammal.

Amnion

In vertebrate animals, the extraembryonic membrane that encloses the fluid-filled amniotic sac containing the embryo.

Yolk Sac

An extraembryonic membrane that develops from the endoderm. The yolk sac produces the embryo’s first blood cells and germ cells and gives rise to the allantois.

Allantois

In animals, and extraembryonic membrane that develops from the yolk sac. The allantois helps dispose of the embryo’s nitrogenous wastes and forms part of the umbilical cord in mammals.

Chorion

In animals, the outermost extraembryonic membrane, which becomes the mammalian embryo’s part of the placenta.

Human Chorionic Gonadotropin (hCG)

A hormone secreted by the chorion that maintains the production of estrogen and progesterone by the corpus luteum of the ovary during the first few months of pregnancy; secreted in the urine is the target of many home pregnancy tests.

Chorionic Villi

Outgrowth of the chorion, containing embryonic blood vessels. As part of the placenta, will absorb nutrients and oxygen from, and pass wastes into, the mother’s bloodstream.

Trimester

In human pregnancy, one of three periods lasting about 3 months.

Labor

The series of events that expel and infant from the mother’s uterus.

Infertility

The inability to conceive after one year of regular, unprotected intercourse.

Assisted Reproductive Technology

Procedure that involves surgically removing eggs from a woman’s ovaries, fertilizing them, and then returning them to the woman’s body.

in vitro Fertilization (IVF)

Uniting sperm and egg in a laboratory container, followed by the placement of a resulting early embryo in the mother’s uterus.