Chapter 25 Reproductive System

Gonads

reproductive organs that produce gametes and hormones; testes and ovaries

gametes

sex cells (sperm and egg)

testes

The male gonads, which produce sperm and secrete male sex hormones (e.g. testosterone).

ovaries

the female gonads; two organs that produce egg cells (gametes) and hormones (e.g. estrogen, progesterone, relaxin, and inhibin)

oocyte

an immature egg cell (gamete); a cell in an ovary that may undergo meiotic division to form an ovum.

ovum (ova)

A mature egg cell (gamete)

scrotum

External sac that contains the testes; sac that regulates the temperature of the testes

seminiferous tubules

within testes, where sperm is produced

epididymis

A long (23'), coiled duct on the outside of the testis which take sperm 3 weeks to travel, while they are maturing and temporarily stored. Debris and damaged sperm are recycled.

rete testis

network of tubules between the seminiferous tubules and the epididymis

Leydig cells (interstitial endocrine cells)

cells within the testes that produce testosterone.

nurse cells (Sertoli cells)

Inside the seminiferous tubules support developing sperm and help regulate sperm production
Stimulated by FSH and testosterone to promote sperm production.
Secrete inhibin to slow rate of sperm production when rate becomes too fast. (Inhibin suppresses FSH production)
Provide blood-testis barrier

Testosterone

the most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty

cremaster muscle

Skeletal muscle that pulls the scrotum closer to the body in cold temperatures and relaxes to let the testicles be farther away from the body in warmer weather

dartos muscle

smooth muscle that wrinkles the scrotal skin when cold

ductus (vas) deferens

muscular passageway conveying sperm to the ejaculatory duct; in the spermatic cord;
extends from the epididymis to the urethra; propels sperm into the urethra by peristalsis during ejaculation

Ampulla of ductus (vas) deferens

can store sperm for several months

seminal glands (vesicles)

glands that produce up to 70% of the volume of semen; the slightly alkaline fluid contains fructose, prostaglandins, fibrinogen

prostate gland

A gland in males that surrounds the urethra and contributes to the seminal fluid. Prostatic fluid is rich in enzymes (e.g. PSA, phosphatase)

bulbourethral glands

the two glands below the prostate that secrete a sticky fluid (containing alkaline mucus) that becomes a component of semen

semen

A thick fluid containing sperm and other secretions from the: seminal glands, prostate gland, and bulbourethral glands

corpora cavernosa

either of two masses of erectile tissue forming the bulk of the penis

corpus spongiosum

the mass of spongy tissue surrounding the male urethra within the penis

spermatogenesis

production of sperm through meiosis

spermatogonia

The diploid stem cells in a testis that divide mitotically to give rise to primary spermatocytes. They are undifferentiated spermatogenic cells.

primary spermatocyte

a cell that divides in Meiosis I, to form two secondary spermatocytes

secondary spermatocytes

Two haploid cells resulting from the first meiotic division of spermatogenesis. Secondary spermatocytes are ready to enter meiosis II.

spermatids

Four immature haploid cells that are formed from two secondary spermatocytes that undergo meiosis II

Spermiogenesis

transformation of spermatids into spermatozoa

spermatozoa

a mature sperm cell

acrosome

A vesicle in the tip of a sperm containing hydrolytic enzymes and other proteins that help the sperm reach the egg.
A region at the head of a sperm cell contains digestive enzymes which, when released during the acrosome reaction, can facilitate penetration of the corona radiata of the egg, and subsequently, fertilization

GnRH (gonadotropin-releasing hormone)

a hormone secreted by the hypothalamus that regulates the pituitary's secretion of gonad-stimulating hormones (FSH and LH)

capacitation

A series of physiological changes that allow the sperm to become motile as well as fertilize the egg.

uterine tubes (fallopian tubes)

tubes extending from each side of the uterus toward the ovary that provide a passage for ova to the uterus

uterus

A hollow muscular organ in the pelvic cavity of the female, in which the embryo is nourished and develops before birth

infundibulum of uterine tube

between the ampulla and the fimbriae of the uterine tube

Fimbriae

Fingerlike projection of the uterine (fallopian) tubes that drape over the ovary.

ampulla of uterine tube

site of fertilization

cervix of uterus

narrow neck of the uterus which projects into the vagina inferiorly

vagina

A muscular, elastic passageway that extends from the uterus to the outside of the body

vulva

external female genitalia; includes the labia, hymen, clitoris, and vaginal orifice

endometrium

inner, mucous membrane lining of the uterus

myometrium

muscular middle layer of the uterus

perimetrium

outer thin layer (serosa, continuous with peritoneum) that covers the surface of the uterus

broad ligament of uterus

peritoneal fold; supports the uterine (fallopian) tubes, uterus and vagina

mammary gland

Specialized organs in mammals that produce milk to nourish the young

lactiferous ducts

milk ducts which carry milk from the mammary glands to the nipple

oogonia

Diploid stem cells.
During fetal development these cells give rise to primary oocytes.

Primary oocytes

Diploid cells resulting from mitosis & differentiation of oogonia during fetal development

Secondary oocytes

After completing meiosis I, these are produced along with a polar body and are released into the fallopian tube.

follicles of ovary

embedded in highly vascular connective tissue of the ovary cortex are many tiny saclike structures, each one of these consist of an immature egg called a primary oocyte, encased by one or more layers of very different follicular cells
place of estrogen and progesterone production

FSH (follicle stimulating hormone)

stimulates secretion of ovarian sex hormones, development of ovarian follicles, and sperm production

LH (luteinizing hormone)

Produced by Anterior lobe of Pituitary Gland. Targets ovaries and testes to stimulate estrogen secretion and oocyte maturation; stimulates sperm production.

secondary oocyte

A haploid cell resulting from the first meiotic division of oogenesis (note that the cytoplasmic division in this case is unequal, producing one large cell with almost all of they cytoplasm - the secondary oocyte- and one smaller cell with virtually no cytoplasm - the first polar body.). A mature secondary oocyte (along with some follicular cells) is released from the ovary during ovulation.

mature (graafian) follicle

large, fluid-filled follicle ready to expel secondary oocyte during ovulation

corpus luteum

empty ovarian follicle that secretes progesterone after release of the secondary oocyte

corpus albicans

degenerated corpus luteum

follicular phase of ovarian cycle

FSH promotes the development of a follicle that secretes estrogen.
An estrogen spike leads to a surge in LH and ovulation around day 14 in the 28-day cycle.
FSH predominates during days 1-13, the ovarian follicles develop and estrogen secretion by follicles is stimulated

luteal phase of ovarian cycle

LH predominates during days 15-28, LH stimulates secretion of progesterone by the corpus luteum

Menstrual Phase of uterine (menstrual) cycle

days 1-5
uterus sheds all but the deepest part of the endometrium

Proliferative Phase of uterine (menstrual) cycle

rising blood estrogen levels during days 6-14, the endometrium thickens

Secretory Phase of uterine (menstrual) cycle

progesterone is predominating during days 15-28, endometrial gland activity increases
coincides with luteal phase of the ovarian cycle

menses

menstruation; monthly uterine bleeding

menarche

the first menstrual period

menopause

the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines