Biology 112 reproductive system

Allantois

In the amniotic egg, a membrane that encloses a space where metabolic wastes collect

Amnion

In the amniotic egg, a membrane surrounding a fluid-filled cavity that allows the embryo to develop in a watery environment.

Amniotic egg

An egg that can exchange gases while retaining water, permitting amniotes to reproduce in dry terrestrial habitats that amphibian eggs cannot tolerate.

Amniotic sac

The fluid-filled sac that contains and protects a fetus in the womb.

Chorion

In the amniotic egg, a membrane that surrounds the entire embryo along with its yolk and allantoic sac

Corpus luteum

A temporary endocrine structure that secretes progesterone.

Egg

an oval or round object laid by a female bird, reptile, fish, or invertebrate, usually containing a developing embryo

Estrogen

A hormone secreted by the ovaries that stimulates the development of female secondary sexual characteristics.

External fertilization

Fertilization that takes place outside the body of the female; in aquatic organisms, for example, eggs and sperm are released into the water.

Fertilization

The union of gametes to produce a diploid zygote.

Follicle-stimulating hormone (FSH)

A hormone secreted by the anterior pituitary gland that stimulates the male and female gonads to secrete testosterone in males and estrogen and progesterone in females.

Gamete

A reproductive haploid cell; gametes fuse in pairs to form a diploid zygote. In many species, there are two types of gametes: eggs in females, sperm in males.

Gonadotropin-releasing hormone (GnRH)

A hormone released by the hypothalamus that stimulates the anterior pituitary gland to secrete luteinizing hormone and follicle-stimulating hormone.

Human chorionic gonadotropin (hCG)

A hormone released by the developing embryo that maintains the corpus luteum.

Internal fertilization

Fertilization that takes place inside the body of the female.

Lutenizing hormone (LH)

A hormone secreted by the anterior pituitary gland that stimulates the male and female gonads to secrete testosterone in males and estrogen and progesterone in females.

Mitosis

In eukaryotic cells, the division of the nucleus, in which the chromosomes are separated into two nuclei.

Meiosis

A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores

Oogenesis

The formation of ova or eggs.

Ovary

In plants, a hollow structure at the base of the carpel in which the ovules develop and which protects the ovules from being eaten or damaged by animals; in animals, the female gonad where eggs are produced.

Oviparity

Laying eggs.

Ovoviviparity

Giving birth to live young, with nutritional support of the embryo from the yolk.

Parthenogenesis

A form of asexual reproduction in which females produce eggs that are not fertilized by males but divide by mitosis and develop into new individuals

Polyspermy

In animals, fertilization by more than one sperm.

Progesterone

A hormone secreted by the vertebrate ovaries that maintains the thickened and vascularized uterine lining

Semen

A fluid that nourishes and sustains sperm as they travel in the male and then the female reproductive tracts

Sperm

The smaller, male gametes.

Spermatogenesis

The formation of sperm.

Testes

The male gonad, where sperm are produced

Testosterone

A steroid hormone, secreted by the testes, that plays key roles in male growth, development, and reproduction.

Viviparity

Giving birth to live young, with nutritional support of the embryo from the mother.

Zygote

The diploid cell formed by the fusion of two gametes.