🍆 | Chapter 26: Reproductive System

Gonads

Primary sex organs that produce sex cells called gametes.

Ovaries

Female gonads that produce oocytes.

Testes

Male gonads that produce sperm and hormones.

Gametes

Sex cells produced by gonads; oocytes in females and sperm in males.

Scrotum

Skin and superficial fascia surrounding the testes, providing a cooler environment for sperm production.

Dartos muscle

Smooth muscle in the skin of the scrotum that regulates testicular temperature.

Tunica vaginalis

Serous membrane lining the scrotal cavity that reduces friction.

Tunica albuginea

Tough, fibrous capsule covering the testis and continuous with septa subdividing testes.

Lobules

Subdivisions of the testes containing seminiferous tubules.

Seminiferous tubules

Coiled tubules within lobules where sperm production occurs.

Spermatogenesis

The process of sperm production occurring within the seminiferous tubules.

Spermatogonia

Stem cells in the seminiferous tubules that undergo mitosis.

Spermatocytes

Cells undergoing meiosis in the process of sperm production.

Spermatids

Cells undergoing spermiogenesis that develop into mature sperm.

Nurse cells (Sertoli cells)

Cells that extend from the tubular capsule to the lumen and form a blood-testis barrier.

Blood-testis barrier

Barrier formed by tight junctions of nurse cells protecting developing sperm from the immune system.

Mitosis

Process producing two identical daughter cells, each containing 46 chromosomes (diploid).

Meiosis

Cell division involved in gamete production resulting in haploid cells.

Haploid

Cells containing 23 chromosomes, produced during meiosis.

Diploid

Cells containing 46 chromosomes, produced during mitosis.

Spermiogenesis

The final stage of spermatogenesis where spermatids develop into mature sperm.

Leydig cells

Large interstitial endocrine cells in the spaces between tubules that produce androgens, such as testosterone.

Reproductive cycle

Major events occurring in the reproductive system over a defined period.

Structure of a sperm

Lacks most organelles and intracellular structures in order to reduce size and mass

Acrosome

Containing enzymes essential to fertilization

Head of sperm

Contains nucleus with densely packed chromosomes

Neck of sperm

Contains both centrioles and microtubules

Middle piece of sperm

Contains mitochondria to provide ATP for tail movement

Tail (flagellum)

Whiplike organelle that moves the sperm

Spermatic cords

Extend between testes and abdominopelvic cavity

Cremaster muscle

Contracts to pull testes closer to body during sexual arousal or when exposed to cold temperature

Path of sperm

Testis to the epididymis, along the ductus deferens, then along the ejaculatory duct to the urethra

Epididymis

Start of the male reproductive tract, coiled tube bound to posterior border of each testis

Ductus deferens (or vas deferens)

40-45 cm (16-18 in.) long, passes through spermatic cord, transports sperm from the epididymis

Ejaculatory duct

Short passageway formed where ampulla of ductus deferens joins with duct of seminal gland

Seminal glands

Also called seminal vesicles

Prostate

Encircles the proximal urethra as it leaves the bladder

Bulbo-urethral glands (Cowper's glands)

Located at the base of the penis, secrete thick, alkaline mucus that helps neutralize acids in the urethra

Root of the penis

A fixed portion that attaches the penis to the body wall

Body (or shaft) of the penis

A tubular, movable portion of the organ

Glans penis (head)

An expanded distal end that surrounds the external urethral orifice

Phases in the male sexual response

Arousal, release of nitric oxide, blood flow increases, erection occurs, ejaculation caused by sympathetic activation

Ovary

Main structures of the female reproductive system, produces oocyte and hormones (estrogens and progesterone)

Oogenesis

Formation and development of the oocyte, begins before birth, accelerates at puberty, ends at menopause

Polar body

A cell that holds discarded chromosomes.

Secondary oocyte

Undergoes meiosis II only if fertilized by a sperm cell.

Ovarian cycle

Consists of three phases: Follicular Phase, Ovulation, and Luteal Phase.

Follicular Phase

The first half of the ovarian cycle.

Ovulation

The midpoint of the ovarian cycle when the oocyte exits from one ovary.

Luteal Phase

The second half of the ovarian cycle where the remaining follicle becomes a corpus luteum.

Corpus luteum

Secretes progesterone and prepares for implantation of an embryo.

Corpus albicans

Pale scar tissue formed by degeneration of the corpus luteum when fertilization does not occur after 12 days.

Uterine tubes

Also known as fallopian tubes or oviducts, they are connected to the uterus.

Infundibulum

Funnel-like expansion adjacent to the ovary with fingerlike projections (fimbriae) that drape over the surface of the ovary.

Oocyte transport

Involves a combination of ciliary movement and peristaltic contraction of smooth muscle in the uterine tube.

Fertilization timing

Must occur within the first 12-24 hours after ovulation.

Uterus

Thick-walled, muscular organ that provides mechanical protection, nutritional support, and waste removal for embryo and fetus.

Perimetrium

The outer surface (serosa) of the uterine wall.

Myometrium

The thick muscular middle layer of the uterine wall, important in delivering the fetus at birth.

Endometrium

Mucosa whose characteristics change with each uterine cycle, consisting of a functional layer and a basal layer.

Fundus

Rounded portion superior to the openings of the uterine tubes.

Body of the uterus

The largest portion of the uterus, making up two-thirds of the organ.

Cervix

Inferior portion of the uterus that projects into the vagina; site for Pap test.

Uterine cycle

Monthly changes in the functional zone of the uterus in response to sex hormone levels.

Menstrual cycle length

Averages 28 days in length, with a range of 21-35 days.

Menarche

The first menstrual cycle, beginning at 11-12 years of age.

Menopause

Occurs between 45-55 years of age, marking the end of menstrual cycles.

Menstrual phase

Days 1-7 of the uterine cycle when the stratum functionalis is shed.

Proliferative phase

Days 8-14 of the uterine cycle when uterine gland basal cells multiply and restore uterine epithelium.

Secretory phase

Days 15-28 of the uterine cycle when uterine glands enlarge, stimulated by progesterone and estrogens.

Vagina

Elastic, muscular tube extending from the cervix to the vestibule, important during sexual intercourse and birth.

Mons pubis

Bulge of adipose tissue deep to the skin and superficial to the pubic symphysis.

Clitoris

Contains erectile tissue comparable to the corpora cavernosa and corpus spongiosum of the penis.

Labia majora

Folds of skin encircling the labia minora and adjacent structures.

Labia minora

Small folds of skin.

Vestibule

Central space bounded by labia minora.

Hymen

Elastic epithelial fold that usually partially blocks the entrance to the vagina.

Greater vestibular glands

Mucous glands activated during sexual arousal, homologous to bulbo-urethral glands of males.

Mammary glands

Located in the fat layer above pectoral muscles, responsible for milk production.

Lactiferous duct

Ducts carrying milk that leave lobules and merge into a single duct.

Lactiferous sinus

Where milk drains before opening onto the body surface through the nipple.

Areola

Brownish skin surrounding the nipple.

Site of spermatogenesis

Seminiferous tubules.

Primary site of fertilization

Fallopian tube.

Primary site of embryo implantation

Uterus.