Cheat Sheet 22: Reproductive System

Gonads

Reproductive structures responsible for producing gametes.

Ovary

Produces eggs (ova). Females have two ovaries.

Testis

Site of sperm and male sex hormone production enclosed within the scrotum for temperature regulation.

Somatic cell

Diploid, non-reproductive cells (E.g., muscle cells, skin cells, nerve cells).

Germ cell

Diploid cells of embryonic origin and gives rise to gametes via meiosis (E.g., spermatogonium, oogonium).

Gamete

Haploid sex cells (E.g., egg and sperm).

Viviparity

Birth to live young that receive nutrients directly from the mother's body.

Oviparity

Fertilized eggs get laid then hatch later.

Ovoviviparity

Internally fertilized eggs hatch and give birth to live young who continue to receive nutrients from the yolk of the egg.

Oviduct (Fallopian/Uterine Tube)

Responsible for moving the eggs from the ovary to the uterus; site of fertilization (where the sperm meets the egg).

Sertoli cells

Stimulated by FSH and surround and nurture the sperm.

Fimbriae

Sweep the egg into the fallopian tube once released from the ovary.

Interstitial cells (Leydig cells)

Secrete male hormones (E.g., testosterone and androgens) in the presence of LH.

Cervix

The muscular canal that connects the vagina to the uterus.

Uterus

Muscular chamber in which the embryo develops until birth; zygote attaches to uterine wall after fertilization.

Vagina

Muscular canal that serves as a birth canal during delivery; connected to the uterus via the cervix.

Epididymis

Coiled tube attached to each testicle that serves as the site of final sperm maturation and storage.

Vas deferens

Transfers sperm from each epididymis to the urethra.

Seminal vesicles

Excrete fluid into the vas deferens upon ejaculation.

Penis

Transports semen into vagina.

Acrosome

Lysosome-like organelle that penetrates the egg.

Pro-nucleus

Haploid (23 chromosomes).

Mid-piece

Plethora of mitochondria for energy.

Tail

Flagellum that produces motion.

Blastocyst

Stage of early embryonic development that follows the morula stage.

Morula

A solid ball of cells resulting from the division of a fertilized ovum.

Zygote

Fertilized egg.

Implantation of blastocyst

The process where the blastocyst attaches to the uterine wall.

Week 5

Heart begins beating.

Week 8

Development of embryo has reached fetus stage.

Week 40

Development has reached full term.

Oogenesis

The process of egg formation in females.

Spermatogenesis

The process of sperm formation in males.

Primary oocytes

Oogonia that have begun meiosis but stopped in prophase I.

Primordial follicle

Structure formed when primary oocytes are surrounded by a single layer of granulosa cells.

Primary follicles

Follicles that develop from primordial follicles when granulosa cells enlarge and increase in number.

Secondary follicles

Follicles that form when fluid-filled vesicles develop and theca cells arise on the outside.

Mature follicles

Follicles that form when vesicles create a single antrum.

Follicular phase

The phase of the menstrual cycle involving the development of the egg and secretion of estrogen.

Ovulation

The midcycle release of the egg, triggered by a surge of LH.

Luteal phase

The phase following ovulation characterized by secretion of estrogen and progesterone from the corpus luteum.

Secondary oocyte

An oocyte that is released from the ovary and completes meiosis II only if fertilized.

Corpus luteum

The structure formed from the remaining follicle after ovulation that secretes hormones.

Corpus albicans

The scar formed when the corpus luteum degenerates if the egg is not fertilized.

Human chorionic gonadotropin (hCG)

Hormone secreted by the placenta that maintains the corpus luteum during pregnancy.

Negative feedback loop

A regulatory mechanism where increased hormone levels suppress further hormone release.

GnRH

Gonadotropin-releasing hormone released by the hypothalamus to stimulate FSH and LH release.

FSH

Follicle-stimulating hormone that promotes the development of sperm and follicles.

LH

Luteinizing hormone that triggers ovulation and testosterone release.

Leydig cells

Cells in the testes that produce testosterone in response to LH.

Sertoli cells

Cells in the testes that support and promote the development of sperm.

Estrogen

Hormone produced by follicles that regulates the menstrual cycle.

Progesterone

Hormone produced by the corpus luteum that prepares the endometrium for implantation.

Menstrual Cycle

The monthly cycle of changes in the female reproductive system, including the follicular, ovulation, and luteal phases.

Fertilization

The process by which a sperm cell unites with an oocyte to form a zygote.

Epididymis

The structure where sperm are stored after maturation in the testes.

Testes

Male reproductive organs where spermatogenesis occurs.

Fallopian tube

The tube through which the egg travels from the ovary and where fertilization occurs.

Granulosa cells

Cells that surround oocytes and are involved in follicle development.