Reproductive System, Meiosis, and Human Development

Comprehensive vocabulary flashcards covering the male and female reproductive systems, meiosis, and the stages of human prenatal development.

Gonads

Organs that secrete sex hormones, such as testosterone and estrogen, and produce gametes through meiosis.

Gametes

Sex cells produced by the gonads; male gametes are called sperm and female gametes are called ova, or egg cells.

Zygote

The new cell formed by the fusion of a sperm and an egg cell during fertilization; it divides to produce all cells in a new individual.

Meiosis

The process during which a cell divides to form daughter cells with half the number of chromosomes, ensuring the correct number in gametes.

Somatic cells

Human body cells that are diploid ($2n$), containing a nucleus with $46$ chromosomes ($23$ pairs).

Seminiferous tubules

Tightly coiled loops within the lobules of the testes where sperm is produced.

Interstitial cells (Leydig cells)

Cells found between seminiferous tubules that produce testosterone.

Sustentacular cells (Sertoli cells)

Cells within seminiferous tubules that provide nutrients for dividing cells, produce inhibin, and support sperm production.

Epididymis

A duct system filled with ductules that serves as the site for sperm maturation and storage.

Spermatic cord

A tube extending from the scrotum to the pelvic cavity containing the ductus deferens, blood vessels, lymph vessels, and nerves.

Cremaster muscle

Smooth muscle in the spermatic cord that controls the height of the testes to regulate temperature.

Seminal vesicles

Glands on the posterior surface of the urinary bladder that produce seminal fluid, which accounts for $60\text{--}70\%$ of semen volume.

Prostate specific antigen (PSA)

A secretion from the prostate gland that dissolves the semen clot in the female reproductive tract to allow sperm to proceed.

Bulbourethral glands (Cowper’s glands)

Paired glands at the base of the penis that secrete a thick, alkaline mucus to neutralize acids and lubricate the glans penis.

Benign Prostatic Hyperplasia (BPH)

A noncancerous enlargement of the prostate that can expand to the point of compressing the urethra.

Cryptorchidism

A disorder in which a testis does not descend into the scrotum, resulting in the failure to produce sperm cells.

Spermatogenesis

The process of sperm cell development which begins at puberty and occurs in the seminiferous tubules.

Spermiogenesis

The final stage of spermatogenesis where spermatids elongate and mature into mature sperm cells.

Acrosome

A structure in the head of a sperm cell containing enzymes necessary for penetrating an egg.

Oogenesis

The production of female gametes (ova) which begins before birth, is suspended until puberty, and ends at menopause.

Ampulla

The expansion at the distal end of the uterine tube where fertilization typically occurs.

Endometrium

The innermost layer of the uterine wall composed of simple columnar epithelium that lines the uterine cavity.

Rugae

Transverse ridges lining the vaginal wall.

Hymen

A vascular partition of mucosa near the distal vaginal orifice, often ruptured during first sexual intercourse.

Alveoli

Milk-producing structures within the lobules of the mammary glands that function during lactation.

Vesicular (tertiary) follicle

A mature follicle containing a large fluid-filled cavity called an antrum; contains a secondary oocyte ($n$).

Corpus luteum

The remnant of a ruptured follicle that secretes progesterone and some estrogen to support pregnancy.

Corpus albicans

Scar tissue that remains in the ovary after the corpus luteum has degraded.

Menarche

The first episode of menstrual bleeding, typically occurring approximately two years after the onset of puberty.

Stratum functionalis

The functional layer of the endometrium that detaches and is shed monthly during menstruation.

Pre-embryonic period

The first $2$ weeks after fertilization during which the zygote divides and implants in the endometrium.

Capacitation

The process sperm undergo as they migrate to the oocyte which enables them to release enzymes for fertilization.

Blastocyst

A stage of development consisting of an outer layer of trophoblast cells and an inner cell mass (embryoblasts).

Human chorionic gonadotropin (hCG)

A hormone secreted by the trophoblast that stimulates the corpus luteum to keep secreting estrogen and progesterone.

Amnion

An extraembryonic membrane that encloses the embryo in a fluid-filled cavity to protect it from trauma and drying out.

Chorion

The outermost extraembryonic membrane which forms the chorionic villi and contributes to the placenta.

Organogenesis

The process during the embryonic period (weeks $3\text{--}8$) where the three germ layers develop into all major organ systems.

Ductus venosus

A fetal vascular shunt that allows blood from the umbilical vein to bypass the liver and flow into the inferior vena cava.

Foramen ovale

A hole in the interatrial septum of the fetal heart that allows blood to flow directly from the right atrium to the left atrium.

Amniocentesis

A procedure done between $14$ and $20$ weeks of pregnancy where amniotic fluid is withdrawn to test for chromosomal abnormalities.