Reproductive System Study Guide

What hormones regulate the synthesis of milk and its ejection?

- prolactin produced by the anterior pituitary gland stimulates the production -oxytocin released by the posterior pituitary is responsible for milk ejection

cremaster muscle

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

Describe the general structure of an ovary and of an ovarian follicle.

Ovaries - held in place by several ligaments; found on both sides of uterus at ends of fallopian tubes -each ovary is surrounded externally by a fibrous tunica albuginea; this is covered externally by a layer of cuboidal epithelial cells called surface epithelium that is actually a continuation of peritoneum -have an outer cortex, which houses the forming gametes, and an inner medulla containing the largest blood vessels and nerves Ovarian follicles - embedded in the highly vascular CT of ovary cortex -tiny saclike structures -each one consists of an immature egg (oocyte) encased by 1 or more layers of very different cells

corona radiata

The layer of granulosa cells that surround an oocyte after is has been ovulated.

blood-testis barrier

This is provided by the sertoli cells. They create a tight junction which prevent blood from making antibodies to destroy developing sperm.

How does the uterine tube participate in helping to move the oocyte toward the uterus?

Uterine tubes receive ovulated oocyte and are site where fertilization generally occurs -during ovulation, tube bends to drape over ovary while fimbriae stiffen and sweep ovarian surface -beating cilia of fimbriae create currents in peritoneal fluid that carry an oocyte into uterine tube, where it begins its journey toward uterus -Oocyte is carried toward uterus by a combo of muscular peristalsis and beating cilia -Nonciliated cells of mucosa have dense microvilli and produce secretion that keeps oocyte moist and nourished

What is the function of the epididymis?

Where sperm mature -comma-shaped organ that arches over the posterior and lateral side of testis -head contains efferent ductules that empty into duct of epididymis (highly coiled duct that completes thee head and forms all of the body and tail of this organ) -sperm can be stored in epididymis for months - if they are held longer, epithelial cells of epididymis phagocytize them -sperm are ejaculated from epididymis - smooth muscle in ducts of epididymis contracts during ejaculation, expelling sperm into ductus deferens

raphe

a central line, like a cord, running over the scrotum from the anus to the root of the penis; it marks the position of the septum scroti.

Distinguish between spermatogenesis and spermiogenesis.

Spermatogenesis: process of forming male gametes (sperm); begins at puberty -lasts 64 to 72 days Spermiogenesis: transformation of a haploid spermatid into a functional sperm -golgi apparatus packages acrosomal enzymes; acrosome forms at anterior end of nucleus and centrioles gather at opposite end -microtubules form flagellum -mitochondria multiply and cluster around proximal portion of flagellum and excess cytoplasm sloughs off -immature sperm gets released from sustentocyte forming mature sperm

Which blood vessels within the uterine wall undergo growth and degeneration during the menstrual cycle?

Spiral arteries - repeatedly degenerate and regenerate in response to changing hormone levels -their spasms cause functional layer to be shed during menstruation -Uterine arteries --> arcuate arteries --> radial arteries --> spiral arteries

cytoplasmic bridge

a temporary thin strand of cytoplasm connecting two microorganisms during conjugation through which structure genetic material may be passed between the cells

menarche

a woman's first menstrual period

puberty

period of life when the reproductive organs grow to adult size and become functional; represents the earliest time that reproduction is possible

seminal fluid

substance in which sperm are suspended that is produced by three glands in the abdominal cavity

menopause

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

LH surge

triggers ovulation

Describe in order (beginning at the external body surface) the structures through which sperm pass as they make their way toward a waiting oocyte.

vaginal orifice -> vaginal canal/lumen -> cervix (external os -> cervical canal -> internal os) -> lumen of uterus -> uterine tube

The following hormones are involved in regulating female reproductive function. Describe the effects of each hormone and identify the cells that secrete the hormone: follicle-stimulating hormone (FSH) luteinizing hormone (LH) gonadotropin-releasing hormone (GnRH) estrogen progesterone inhibin

- GnRH: stimulates the anterior pituitary to produce/release LH and FSH - FSH: exerts its main effects on the granulose cells of late secondary and vesicular follicles causing them to release estrogen - LH: prods the thecal cells to release androgens, diffuse through the basement membrane where the granulosa cells convert them to estrogens, stimulates corpus luteum to produce larges amounts of progesterone and some estrogen -estrogen: as levels rise= negative feedback = inhibiting release of FSH and LH, in ovary enhances output of estrogens by intensifying the effect of FSH on follicle maturation - inhibin: exerts negative feedback, controls FSH release during this period, only dominant follicle will survive - progesterone: helps maintain the stratum functionalis and is essential for maintaining pregnancy should conception occur

Explain the role of the ANS (parasympathetic and/or sympathetic divisions) in producing the female sexual response.

- arousal phase: mediated by parasympathetic reflexes, characterized by relaxation of vascular smooth muscle in genital region and secretion by vaginal and vestibular glands - orgasm phase: mediated by sympathetic nervous system, nervous stimulation produces systemic effects (increase muscle tension, HR, BP) and rhythmic contractions of uterus, vagina, and perineal muscles

Describe the feedback loops (positive and negative) involved in regulating GnRH, FSH, and LH secretion in the various stages of the ovarian cycle.

- as estrogen levels in the plasma rise, they exert negative feedback on the hypothalamus and anterior pituitary, inhibiting the release FSH and LH - rising progesterone and estrogen blood levels exert a powerful negative feedback effect on the hypothalamus and the anterior pituitary release of LH and FSH

What is the significance of the unequal distribution of cytoplasm, which results in the formation of polar bodies, during oogenesis?

- ensures that a fertilized egg has ample nutrients for its six to seven day journey to the uterus

Describe the relative blood concentrations of both estrogen and progesterone during the three phases of the ovarian cycle (i.e., when does the blood concentration of each hormone increase? decrease?)

- estrogen: begins to have a great increase close to ovulation and peaks just beforehand, decreases afterwards with one small peak in the luteal phase - progesterone: stays steady during follicular and then begins to increase just before ovulation and peaks in the middle of the luteal phase

What is the effect of human chorionic gonadotropin (hCG) on the corpus luteum?

- extends the lifespan for about 3 more months

Which hormone (estrogen or progesterone) is in higher blood concentration during the follicular phase of the ovarian cycle? during the luteal phase?

- follicular phase: estrogen - luteal phase: progesterone

What menstrual cycle events are associated with the fluctuating levels of ovarian hormones?

- proliferative: ovulation as response to sudden release of LH from the anterior pituitary - secretory: rising levels of progesterone cause the spiral arteries to elaborate and convert the functional layer to a secretory mucosa, corpus luteum degenerates toward the end of the secretory phase as LH blood levels decline if fertilization has not occurred

Explain how testosterone secretion is regulated (after puberty), with mention of GnRH, FSH and ICSH, inhibin, and feedback inhibition.

- rising levels feed back (negative) to inhibit hypothalamic release of GnRH and act directly on the anterior pituitary gland to inhibit gonadotropin release - less FSH and ICSH are released - inhibin inhibits also when sperm count is higher than normal

What is the role of sperm penetration in the development of an ovum?

- sperm penetration triggers completion of meiosis II which produces an ovum and second polar body

Describe the origin and function of a corpus luteum. What is the life span of a corpus luteum if fertilization does not occur?

- the remaining granulosa cells enlarge and along wit the internal thecal cells they form a new, quite different endocrine structure at the site of ruptured follicle - secretes progesterone, small amounts of estrogen and inhibin - lasts only for 14 days; starts degenerating after 10 days and its hormonal output ends

What health risks are increased in post-menopausal women (who do not participate in hormone replacement therapy)?

- without sufficient estrogen the reproductive organs and breasts begin to atrophy, the vagina becomes dry, and vaginal infections become increasingly common - irritability and depression, intense vasodilation of the skin's blood vessels, cause uncomfortable, sweat-drenching "hot flashes" - gradually thinning skin and loss of bone mass - cardiovascular disease because of slowly rising total blood cholesterol levels and falling HDL levels

What are the female secondary sex characteristics?

-Breast development -increasing deposition of subcutaneous fat, especially in hips and breasts -development of wider and lighter pelvis (adaptations for childbirth)

Describe the general structure and function of the penis.

-Copulatory organ that delivers sperm into female reproductive tract -penis and scrotum hang suspended from perineum and make up external genitalia -consists of attached root and free body that ends in an enlarged tip (glans penis) -skin covering penis is loose and extends distally around glans to form a cuff called prepuce (foreskin) -internally - contains spongy urethra and 3 long cylindrical bodies (corpora) of erectile tissue, each covered by sheath of dense fibrous CT - spongy network of CT and smooth muscle riddled with vascular spaces -midventral erectile body (corpus spongiosum) surrounds urethra - expands distally to form the glans and proximally to form part of root called bulb of penis - crura of the penis: proximal ends, each crus is attached to the ramus of the ischium/pubis

What is the role of the theca interna?

-Inner layer of the theca folliculi that is highly vascularized and contains cuboidal cells that produce steroids in response to LH (produce androgen)

Describe the composition of semen.

-Milky white, somewhat sticky mixture of accessory gland secretions and sperm Contain many substances: -prostaglandins - cause viscosity of mucus guarding entry of uterus to decrease; also stimulate reverse peristalsis in uterus -ATP provides energy -hormone relaxin and certain enzymes in semen enhance sperm motility -certain ingredients suppress immune response in female's reproductive tract -antibiotic chemicals destroy some bacteria -clotting factors in semen coagulate it just after it is ejaculated - causes sperm to stick to walls of vagina -Alkaline (pH 7.2-8.0) - helps neutralize acidic environment of male's urethra and female's vagina

Distinguish between the following in terms of structure and stage of development: primordial follicle; primary follicle; secondary follicle; tertiary follicle (also, antral or Graafian follicle); corpus luteum.

-PRIMORDIAL FOLLICLE: immature oocyte surrounded by 1 layer of follicle cells. -PRIMARY FOLLICLE: 2+ layers of cuboidal or columnar granolas cells -SECONDARY FOLLICLE: fluid-filled pockets between layers of granulosa cells. -MATURE FOLLICLE: fluid filled cavity is very large (antrum). builds from surface of the ovary. Ovulation begins when mature oocyte ruptures, ejecting oocyte. after ovulation, the ruptured follicle transforms into corps luteum.

In what stage is the developing oocyte in each of the follicles listed above (#22)?

-Primordial follicles, primary follicles, secondary follicles all contain primary oocyte -Mature tertiary/vesicular follicle - secondary oocyte is formed

Identify the male accessory sex glands.

-Seminal glands -Prostate -Bulbo-urethral glands

Describe the secretions of each of the above glands (#9).

-Seminal glands: secretes yellowish viscous alkaline fluid containing fructose sugar, citric acid, coagulating enzyme, prostaglandins, and other substances that increase sperm motility or fertilizing ability; accounts for 70% of semen volume -Prostate: secretes milky, slightly acidic fluid that contains nitrate (nutrient source) and several enzymes including one called prostate-specific antigen (PSA); accounts for 1/3 of semen volume; plays a role in activating sperm -Bulbo-urerthral glands: produce thick, clear mucus, some of which drains into spongy urethra where it neutralizes traces of acidic urine; also lubricates the glans penis when a man becomes sexually excited

Identify the characteristics of the various phases of follicular development: primordial follicle, primary follicle, secondary follicle, antral follicle.

-ovarian follicles are specialized structures in which oocytes grow and undergo meiosis -the earliest type of follicle, whose wall consists of a single layer of flattened epithelial-type cells (called follicular cells), is called a primordial follicle (2 million in each ovary at birth) -when a primordial follicle is activated (this occurs almost a year before its possible ovulation), the squamouslike cells surrounding the primary oocyte grow, becoming cuboidal cells, and the oocyte enlarges. the follicle is now called a primary follicle -next, the follicular cells proliferate, forming a stratified epithelium around the oocyte. as soon as more than one cell layer is present, the follicle is called a secondary follicle and the follicle cells take on the name granulosa cells. (grows tremendously during this stage!) -the secondary follicle stage ends when a clear liquid begins to accumulate between the granulosa cells, producing the early vesicular (antral) follicle. when six to seven layers of granulosa cells are present, the fluid between the granulosa cells coalesces to form a large fluid-filled cavity called the antrum (cave). the presence of the antrum distinguishes vesicular follicles from all prior follicles (preantral follicles).

In what stage of meiosis are primary oocytes at birth? What hormone causes the resumption of meiosis in females following the onset of puberty?

-primary oocytes rested in meiosis I at birth -FSH rescues a small number of growing follicles from apoptosis.

Name in order (outermost to innermost) the three tissue layers of the uterine wall.

1. Perimetrium - incomplete outermost serous layer 2. Myometrium - bulky middle layer, composed of interlacing bundles of smooth muscle -contracts rhythmically during childbirth to expel the baby from the mother's body 3. Endometrium - mucosa that lines uterine cavity -mucosa consists of a simple columnar epithelium and thick lamina propria -if fertilization occurs, the young embryo burrows into endometrium and resides there for rest of its development

Explain the role of the parasympathetic and sympathetic divisions of the ANS in producing the male sexual response (i.e., erection and ejaculation).

1. Erection - under parasympathetic control 2. Ejaculation - under sympathetic control -When impulses provoking erection reach a critical level, a spinal reflex is initiated, and a massive discharge of nerve impulses occurs over the sympathetic nerves serving the genital organs: -ductus deferens, prostate, seminal glands contract, emptying their contents into prostatic urethra while bladder internal sphincter muscle constricts -semen in urethra triggers a spinal reflex through somatic motor neurons - bulbospongiosus muscles of penis undergo a series of contractions, propelling semen - accompanied by orgasm and many systemic changes like rapid heart beat and elevated BP -followed by resolution - activity of sympathetic nerve fibers constricts internal pudendal arteries, reducing blood flow into penis and activates small muscles that squeeze cavernous bodies, forcing blood from penis to general circulation

Identify and describe the three major phases of the ovarian cycle.

1. Follicular phase: period when a cohort of vesicular follicles begins to secrete increasing amounts of estrogens and one of these follicles is selected as dominant follicle -dominant follicle: one of the vestibular follicles becomes more sensitive to FSH than the others and outcompetes the other follicles for FSH -generally lasts from 1st to 14th day of ovarian cycle, at which point ovulation occurs 2. Ovulation: occurs when ovary wall ruptures and expels secondary oocyte, still surrounded by its corona radiata, into peritoneal cavity 3. Luteal phase: period of corpus luteum activity, days 14- 28; always 14 days from the time of ovulation to end of the cycle -ruptured follicle collapses after ovulation and antrum fills with clotted blood and is absorbed -remaining granulosa cells enlarge and form corpus luteum with internal theca cells -corpus luteum supplies high levels of progesterone and estrogens that characterize luteal phase -if pregnancy does not occur, corpus luteum degenerates and hormonal output ends; a scar is left called corpus albicans -last 2-3 days the endometrium begins to erode

Name the two strata of the endometrium. Which of these two layers undergoes cyclic growth and sloughing-off in response to changing blood levels of the ovarian hormones?

1. Functional layer - stratum functionalis -undergoes cyclic changes in response to blood levels of ovarian hormones and is shed during menstruation (about every 28 days) 2. Basal layer - stratum basalis -stem cells found in this thinner layer form a new functional layer after menstruation ends

Identify and describe the three major phases of the uterine (menstrual) cycle

1. Menstrual phase (Days 0-4): -uterus sheds all but the deepest part of its endometrium -functional layer of endometrium detaches from uterine wall - process accompanied by bleeding for 3-5 days -detached tissue and blood pass out through vagina as menstrual flow -by day 4, growing ovarian follicles start to produce more estrogens 2. Proliferative (preovulatory) phase (Days 5-14): endometrium rebuilds itself -basal layer of endometrium generates a new functional layer under influence of rising blood levels of estrogens; as this layer thickens, its glands enlarge and its spiral arteries increase in number - endometrium becomes thick and well vascularized -estrogens induce endometrial cells to synthesize progesterone receptors -cervical mucus thins and ovulation occurs 3. Secretory (postovulatory) phase (Days 15-28): endometrium prepares for an embryo to implant -rising levels of progesterone from corpus luteum act on estrogen-primed endometrium causing spiral arteries to elaborate and converting functional layer to secretory mucosa -endometrial glands enlarge, coil, and begin secreting nutrients into uterine cavity- nutrients sustain embryo until it has implanted in blood-rich endometrial lining -cervical mucus becomes viscous again as progesterone levels rise forming cervical plug which helps to block entry of sperm, pathogens and foreign materials -if fertilization hasn't occurred, corpus luteum degenerates

List in order and describe the major steps in spermatogenesis. Your answer should make reference to steps involving mitosis, meiosis I, or meiosis II; and also make reference to primary spermatocytes; secondary spermatocytes; spermatids; sperm.

1. Outermost tubule cells are stem cells called spermatogonia - divide more or less continuously by mitosis -when puberty hits, mitotic division of a spermatogonium results in 2 daughter cells: --> 1. Type A daughter cells - remains at basal lamia to maintain the pool of dividing germ cells --> 2. Type B daughter cells - gets pushed toward lumen, where it becomes a primary spermatocyte destined to produce 4 sperm 2. Meiosis: spermatocytes to spermatids -each primary spermatocyte undergoes meiosis I, forming 2 smaller haploid cells called secondary spermatocytes -secondary spermatocytes continue on rapidly into meiosis II -their daughter cells called spermatids are small round cells which large spherical nuclei, seen close to lumen of tubule -midway through spermatogenesis, developing sperm turn off almost all their genes and compact their DNA into dense pellets 3. Spermiogenesis: -each spermatid has correct chromosomal number for fertilization, but must undergo spermiogenesis during which it elongates, sheds its excess cytoplasmic baggage, and forms a tail

Describe the location and general function of each of the following testicular cells: spermatogenic cells (spermatogonia); sustentacular cells (Sertoli cells); interstitial cells (Leydig cells).

1. Spermatogenic cells: cells that give rise to sperm; found enveloped by sustentocyte and can be seen at many different stages of cell division 2. Sustentocytes (Sertoli cells): large, columnar cells; act as supporting cells and play several roles in sperm formation -have tight junctions between each other that form the blood testis barrier -provide nutrients and essential signals to dividing cells, even telling them to live or die -move spermatocytes and spermatids to lumen -secrete testicular fluid that provides transport medium for sperm in lumen -phagocytize faulty spermatogenic cells and excess cytoplasm sloughed off as spermatids transform into sperm -produce 2 proteins that help regulate spermatogenesis - androgen-binding protein (ABP) keeps concentration of testosterone near spermatogenic cells high which stimulate spermatogenesis; hormone inhibin p inhibits FSH release from anterior pituitary inhibiting spermatogenesis 3. Interstitial endocrine cells (Leydig): lie in the soft CT surrounding seminiferous tubules -produce androgens (most importantly testosterone) and small amounts of estrogens which they secrete into surrounding interstitial fluid 4. Myoid cells: smooth muscle-like cells that surround each seminiferous tubule in 3-5 layers -by contracting rhythmically, myoid cells may help to squeeze sperm and testicular fluids through tubules and out of testes

Describe the female external genitalia.

Called the vulva or pudendum -includes the mons pubis, labia, clitoris, and structures associated with the vestibule Mons pubis: fatty, rounded area overlying pubic symphysis; after puberty, pubic hair covers the skin of this area Labia majora: running posteriorly from mons pubis; 2 elongated hair-covered fatty skin folds; homologues of male scrotum; enclose labia minora Labia minora: two thin, hair-free skin folds homologous to spongy urethra of penis; enclose a recess called the vestibule Vestibule: contains external openings of urethra and vagina; bulbs of vestibule engorge with blood and help vagina grip penis Greater vestibular glands: flank the vaginal opening; pea-sized; homologues to bulbo-urethral glands; release mucus into vestibule and help to keep it moist and lubricated; vestibule and labia minora come together at posterior end to form ridge called fourchette Clitoris: anterior to vestibule; small protruding structure composed of erectile tissue; exposed portion is glans of clitoris and it is hooded by skin fold called prepuce of clitoris formed by junction of labia minora folds -body of clitoris has dorsal erectile columns and becomes swollen with blood during stimulation

Explain the mechanism that produces an erection of the penis.

Erection - enlargement and stiffening of penis -results from engorgement of erectile bodies with blood -sexual excitement triggers a parasympathetic reflex that promotes release of nitric oxide locally - relaxes smooth muscle in penile blood vessel walls, dilating these arterioles and erectile bodies fill with blood -expansion of corpora cavernosa compresses their drainage veins - retards blood outflow and maintaining engorgement -various sexual stimuli can trigger erection - tactile stimulation, sights, sounds, smells - CNS responds by activating parasympathetic neurons that innervate internal pudendal arteries that serve the penis

Hormonal effects of estrogen, progesterone, and testosterone

Estrogen: stimulates growth and maturation of reproductive organs and breasts at puberty and maintain their adult size and function -promotes proliferative phase of uterine cycle -stimulates production of watery cervical mucus and activity of fimbriae and uterine tube cilia -promotes oogenesis and ovulation -stimulates growth of uterus and enlargement of mammary glands and external genitalia during pregnancy -promotes long bone growth and female pattern of fat deposit -anabolic effects; enhances HDL and reduces LDL blood levels Progesterone: cooperates with estrogens in stimulating growth of breasts; promotes secretory phase of uterine cycle -stimulates production of viscous cervical mucus -surge after ovulation enhances beating of cilia in uterine tube which promotes meeting of sperm and oocyte Testosterone: stimulates formation of male reproductive ducts, glands, and external genitalia; promotes descent of testes -stimulates growth and maturation of internal and external genitalia at puberty -required for normal spermatogenesis

What are the male secondary sex characteristics?

Features induced in nonreproductive organs by the male sex hormones; develop at puberty -appearance of pubic, axillary, and facial hair -enhanced hair growth on chest or other body areas in some men -larynx enlargement, which causes deepening of the voice -thicker and oilier skin (which predisposes young men to acne) -increased size and density of bones -increased size and mass of skeletal muscles

The following secretions are involved in regulating male reproductive function. Describe the effects of each and identify the cells that secrete them: -follicle-stimulating hormone (FSH) -luteinizing hormone (LH) in males, also known as interstitial-cell stimulating hormone (ICSH) -androgen-binding protein (ABP) -gonadotropin-releasing hormone (GnRH) -inhibin -testosterone

GnRH: hypothalamus releases it --> reaches the anterior pituitary via hypophyseal portal veins; causes anterior pituitary gonadotropic cells to release FSH and LH FSH: released by gonadotropic cells; indirectly stimulates spermatogenesis by causing sustentocytes to release ABP LH: released by gonadotropic cells; stimulates interstitial endocrine cells to secrete testosterone Interstitial-cell stimulating hormone: acts on testes to cause cells to grow and make testosterone Androgen-binding protein: released by sustentocytes; keeps local concentration of testosterone high Inhibin: released by sustentocytes; feeds back on anterior pituitary, decreasing FSH release Testosterone: released by interstitial endocrine cells -essential for spermatogenesis; acts at other body sites to stimulate maturation of sex organs, development and maintenance of secondary sex characteristics, and libido -negative feedback by testosterone inhibits FSH and LH release from anterior pituitary and GnRH release from hypothalamus

Describe the structure of a mature sperm cell and tell how each part of the sperm (i.e., head, midpiece, tail) contributes to its overall function.

Head - genetic region; consists almost entirely of its flattened nucleus which contains compacted DNA -acromosome adheres to top of nucleus; contains hydrolytic enzymes that enable sperm to penetrate and enter an egg Midpiece - metabolic region -contains mitochondria spiraled tightly around microtubules of the tail -mitochondria provide metabolic energy (ATP) needed for whiplike movements of tail that will propel sperm along its way in female reproductive tract Tail - locomotor region; typical flagellum

What hormonal event triggers ovulation and causes the ruptured follicle to develop into a corpus luteum?

LH surge - sudden burst of LH released by anterior pituitary about midcycle -rouses primary oocyte from its resting state and it completes its first meiotic division forming a secondary oocyte that continues on to metaphase II -day 14 LH increases local vascular permeability and triggers an inflammatory response that promotes release of metalloproteinase enzymes that weaken ovary wall - blood stops flowing through protruding part of follicle wall; wall forms a hole and ovulation occurs -also transforms ruptured follicle into corpus luteum

At birth, primary oocytes are arrested in what phase of meiosis?

Late prophase I

What are the male and female gametes called?

Male: sperm Female: ova (eggs)

Name and describe the location of both the male and female gonads.

Male: testes - lie within the scrotum Female: ovaries - held by fimbriae of uterine tubes

What are the male and female sex hormones?

Male: testosterone Female: estrogen; progesterone

Describe the general structure and function of the mammary glands of the breasts. Can you explain why males can develop breast cancer?

Mammary glands: modified sweat glands present in both sexes; normally function only in lactating females where they produce milk in response to hormonal stimulation to nourish an infant -each one is contained within subcutaneous tissue of a rounded, skin-covered breast anterior to pectoral muscle of thorax -each gland consists of 15-25 lobes - lobes are padded and separated from each other by fibrous CT and fat; interlobar CT forms suspensory ligaments that attach breast to underlying muscle fascia and overlying dermis -lobules are within the lobes and contain glandular alveoli that produce milk when woman lactates - these glands pass milk to lactiferous ducts; just deep to areola each duct has a dilated region called lactiferous sinus where milk accumulates during nursing -areola is slightly below center of each breast and surrounds nipple **description of mammary glands only applies to nursing women** -

Hypothalamic-pituitary-gonadal (HPG) axis

Production of gametes and sex hormones is regulated by sequence of hormonal events involving hypothalamus, anterior pituitary gland, and gonads

Describe the structure and function of the scrotum.

Scrotum - sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at root of penis -covered with sparse hairs, contains paired oval testes -midline septum divides scrotum providing a compartment for each testis -Superficial location - provides a temperature 3 degrees (celsius) lower than core body temp so that sperm can be produced -affected by temperature changes: --> cold - testes are pulled closer to warm body wall; scrotal skin wrinkles, decreasing its surface area and increasing its thickness to reduce heat loss 2 sets of muscles help to maintain a fairly constant intrascrotal temperature: 1. Dartos muscle - layer of smooth muscle in superficial fascia, wrinkles the scrotal skin 2. Cremaster muscles - bands of skeletal muscle that arise from internal oblique muscles of trunk, elevate the testes

Name (in order) and describe the location of the ducts through which a sperm travels as it moves from the seminiferous tubules of the testis to the body exterior.

Seminiferous tubules → straight tubule → rete testis → efferent ducts → epididymis → vas deferens → ejaculatory duct → urethra

amenorrhea

absence of menstruation -usually caused by low levels of body fat - adipose cells help convert adrenal androgens to estrogens are source of leptin which plays critical role in onset of puberty in females -leptin informs hypothalamus whether energy stores are sufficient to support high energy demands of reproduction; if not, reproductive cycles are shut down

Development of which broad category of follicle, pre-antral or antral, is regulated by the gonadotropins, FSH and LH?

antral stage is gonadotropin-dependent -depends on FSH to develop the tertiary follicle (where meiosis I resumes) -small pockets of fluid between granulose cells become one large fluid pocket

tunica albuginea

fibrous capsule of the testes

coitus

sexual intercourse; copulation

dartos muscle

smooth muscle; wrinkles the scrotal skin when cold

Describe the structure of the testes.

surrounded by 2 tunics: 1. tunica vaginalis - outer; serous membrane 2. tunica albuginea - fibrous capsule; dense irregular CT -- septa extending inward from tunica albuginea divide testis into 250 wedge-shaped lobules - each contains 1 to 4 tightly coiled seminiferous tubules --> converge to form straight tubule that conveys sperm into rete testis; then move on to efferent ductules and enter epididymis (hugs external testis surface posteriorly) - myoid cells: smooth muscle-like, surround each seminiferous tubule, 3-5 layers - spermatic cord supplies testes

What is ovulation?

the release of an egg from the ovary into one of the fallopian tubes -generally fewer than 500 oocytes are ovulated during a woman's lifetime

zona pellucida

the thick transparent membrane surrounding a mammalian ovum before implantation -A thick, transpartent coating rich in glycoproteins that surrounds an oocyte