A&P II - Unit 5: Reproductive System

Vagina

A canal lined with mucous membrane extending from the exterior of body to cervix of uterus.

Embryonic Development: 3rd through 8th week

3 primary germ layers differentiate from bilaminar embryonic disc (gastrulation) --DON'T NEED TO KNOW THE GERM LAYERS-- • Ectoderm gives rise to nervous system and epidermis • Mesoderm gives rise to connective tissues and muscles • Endoderm gives rise to gastrointestinal tract, urinary bladder and urethra, and respiratory tract Development of the placenta and umbillical cord All major organs appear during 4th-8th weeks of development All major body systems have begun development by end of eighth week, although most functions are minimal NOTE: By the end of the 8th week embryo starts to have precursor to major organs (shift from embryo to fetus)

Describe semen to include its function

A mixture of sperm and seminal fluid. FUNCTIONS: • Transportation of sperm to enable sexual reproduction and fertilization. • Neutralizes the acidity of the male urethra and female vagina - Semen is slightly alkaline (7.2-7.7) VOLUME of semen in typical ejaculate is 2.5-5mL, with 50-150 million sperm per mL • Large number of sperm necessary for fertilization to be successful- only a tiny fraction will ever reach the female gamete. • Infertility when <20 million sperm per mL

Male reproductive accessory glands

Accessory sex glands secrete most of the liquid portion of semen that protects sperm and facilitates their movement. SEMINAL VESICLES: paired, convoluted, pouchlike • Secrete an alkaline, viscous fluid (60% total semen vol) with fructose (used by sperm for ATP production), clotting proteins, and prostaglandins (contribute to sperm viability and motility). Alkalinity helps neutralize acidic environments in male urethra and female reproductive tract. PROSTATE: single gland about the size of a golfball • Secretes fluid (25% total semen vol) with citric acid (used by sperm for ATP production) proteolytic enzymes, and seminalplasmin (antibiotic- decreases bacteria in semen and lower female reproductive tract). Contributes to sperm motility and viability BULBOURETHRAL GLANDS (Cowper's gland): paired, pea-sized • Inferior to prostate on either side of the membranous urethra • Secrete mucus for lubrication and alkaline fluid to neutralize acids from urine in urethra and protect sperm.

State the effect of the acidic environment of the vagina on microbial growth and sperm

Acidic environment retards microbial growth, but also is harmful to sperm • Alkaline components of semen (from seminal vesicles) raise the pH and increase sperm viability

State what occurs at puberty for a female that starts the Female Reproductive Cycle

At puberty GnRH, LH & FSH begin to be secreted in greater quantities and in a cyclical pattern. • Vagina, uterus, uterine tubes, and external genitalia enlarge • Secondary sexual characteristics develop: - Adipose tissue is deposited at the breasts and hips - Ducts of breasts, pubic and axillary hair, and libido all develop

Describe hormonal regulation of the male reproductive system

At puberty, GnRH stimulates secretion of: • LH and FSH Luteinizing hormone (LH) • Stimulates Leydig cells to secrete testosterone Follicle-stimulating hormone (FSH) • With testosterone, stimulates spermatogenesis Inhibin (from Sertoli cells) • Released when sufficient spermatogenesis has occurred. • Inhibits FSH to help regulate the rate of spermatogenesis Negative feedback regulation mechanism • High testosterone inhibits secretion of GnRH and LH

Breast, Cervical, & Prostate Cancer: Detection/Prevention

BREAST CANCER • Regular self breast exams starting at age 20, yearly mammograms starting at age 40. • Genetic testing: BRCA1, BRCA2 • Increased risk: Use of oral contraceptives, hormone replacement therapy, alcohol use, overweight/obesity after menopause • Decreased risk: having children, breastfeeding, being physically active CERVICAL CANCER • Yearly pap smears (+ HPV testing) • HPV is involved in virtually all cervical cancer cases! Also increases risk: smoking PROSTATE CANCER • No concrete recommendation for testing, can have a blood and rectal exam • Increased risk: diets high in dairy, supplement use (vitamin E, folic acid, perhaps selenium). SELECT trial! • Decreased risk: diets high in folate

Pregnancy

Begins with fertilization and is a time when the fertilized egg undergoes implantation, embryonic and fetal development, and birth.

Leydig Cells

Between seminiferous tubules within testes. Secrete the male sex hormone testosterone.

Early Embryonic Development: Implantation

Blastocyst attaches to the endometrium (~6 days post-fertilization). • Orients with embryoblast closest to the endometrium. Endometrium enlarges and develops more blood vessels - becomes decidua which later becomes the maternal portion of the placenta. Nourishes the embryo.

Umbilical Cord

CONNECTS PLACENTA TO EMBRYO/FETUS • Forms from extraembryonic mesoderm surrounded by amnion • Consists of two umbilical arteries (oxygen-poor blood) and one umbilical vein (oxygen-rich blood) • Scar after delivery becomes umbilicus (navel) NOTE: • Umbilical arteries carry blood away from the fetal heart to the placenta • Umbilical vein carries blood back to the fetal heart (placenta to the heart)

Explain the mechanisms that move the oocyte into the uterine tube and then onward to the uterus

Ciliated epithelial cells lining tube and peristaltic contractions of smooth muscle transport secondary oocyte or zygote (after fertilization) through the tube and into the uterus for implantation

Structure/Function of Penis

Considered a supporting structure in the male reproductive system. • Contains the urethra which provides a passageway for ejaculation of semen and excretion of urine BODY OF THE PENIS IS MADE UP OF 3 CYLINDRICAL MASSES OF ERECTILE TISSUE: 1) 2 CORPORA CAVERNOSA (sing.: corpus cavernosum) 2) CORPUS SPONGIOSUM: contains spongy urethra 3) Distal end of corpus spongiosum is enlarged to form GLANS PENIS

Distinguish between fraternal and identical twins

DIZYGOTIC (fraternal) • Occur if two secondary oocytes are released and fertilized by two different sperm. Not genetically identical. MONOZYGOTIC (identical) • Occur if a single fertilized zygote developing cells separate into two embryos (0-8 days).

Describe the Menstrual Phase in the Female Reproductive Cycle

Day 1-5 DUE TO A DROP IN LEVELS OF PROGESTERONE, ESTROGEN, & INHIBIN, THE FUNCTIONAL LAYER OF THE ENDOMETRIUM OF THE UTERUS SLOUGHS OFF, LEAVING ONLY THE BASAL LAYER BEHIND • Low levels of female sex hormones cause constriction of ovarian arteries and deprive endometrial cells of oxygen. Cells start to die. • 50-150 mL of discharge (blood, tissue fluid, mucus, epithelial cells) LACK OF NEGATIVE FEEDBACK ALLOWS FSH LEVELS TO INCREASE. FSH CAUSES SEVERAL PRIMORDIAL FOLLICLES OF OVARIES TO DEVELOP INTO PRIMARY AND THEN SECONDARY FOLLICLES.

Describe the Ovulation Phase in the Female Reproductive Cycle

Day 14 MATURE FOLLICLE RUPTURES THROUGH OVARIAN WALL, RELEASING THE SECONDARY OOCYTE INTO THE PELVIC CAVITY • Gradual increase in estrogen levels starts to have a positive feedback effect on GnRH and LH secretion. • Surge in LH causes rupture of mature follicle and expulsion of secondary oocyte. • Ovulated secondary oocyte is surrounded by cells of corona radiata (inner layer of follicular cells). • Ovulated oocyte is swept into uterine tube by cilia on fimbriae of infundibulum.

Ectopic Pregnancy

Embryo implants outside the uterine cavity. Most common site is the uterine tube. • Can be caused by tubal ligation, various disorders that result in scar tissue being present in the uterine tubes, smokers are 2x as likely to have ectopic pregnancies. • Life-threatening to the mother because uterine tube may rupture resulting in internal hemorrhaging. • Treated with a drug (methotraxate) that causes the embryonic cells to stop dividing or surgery to remove embryo.

Describe the Preovulatory Phase in the Female Reproductive Cycle

Follicular, Proliferative Phase (Day 6-13) BY DAY 6 A DOMINANT SECONDARY FOLLICLE HAS EMERGED. IT SECRETES ESTROGEN & INHIBIN • Estrogens and inhibin decrease FSH secretion and other (less-developed) follicles stop growing. • Dominant follicle develops into mature Graafian follicle. As the antrum fills with fluid it forms a blister-like bulge on the surface of the ovary. Ready for ovulation! ESTROGENS STIMULATE THE REPAIR OF THE ENDOMETRIUM IN THE UTERUS • Basal layer cells undergo mitosis. • Functional layer forms and thickens GRADUAL INCREASE IN ESTROGEN LEVELS STARTS TO HAVE A POSITIVE FEEDBACK EFFECT ON GnRH & LH SECRETION ....

Embryonic Development: 2nd week of development

Form chorion (precursor to placenta) --> chorion forms placenta Trophoblast develops into two layers and secretes human chorionic gonadotropin (hCG) hormone to maintain the corpus luteum and prevent menstruation Embryoblast develops into flat disc (embryonic disc) with 2 layers: Development of the amnion and amniotic cavity • Small cavity forms in epiblast (amniotic cavity) • Initially forms a membrane that surrounds embryo and adheres to it • Space slowly fills with amniotic fluid, and acts as shock absorber and temperature regulator. Amniotic fluid is inhaled and exhaled by the fetus and essential for proper lung development. It helps form the GI tract and produce urine.

State the functions of the sperm cell's head, acrosome, and middle piece

HEAD CONTAINS THE ACROSOME & NUCLEUS • ACROSOME: Caplike vesicle, contains enzymes for penetrating the female gametes to bring about fertilization • NUCLEUS which contains 23 chromosomes MIDDLE PIECE: Contains mitochondria that provide energy for locomotion Third structural unit is the tail

List the major regions of the Uterus and describe its blood supply

MAJOR REGIONS: Fundus, body, and cervix EXTENSIVE BLOOD SUPPLY: • Uterine, arcuate, radial, straight and spiral arteries

Describe Erectile Tissue

Numerous blood sinuses surrounded by smooth muscle and elastic connective tissue • Upon sexual stimulation parasympathetic fibers initiate and maintain an erection. • Smooth muscle relaxes, veins constrict, and blood pools.

Female Reproductive System Organs

OVARIES • Paired female gonads in abdominal cavity UTERINE (FALLOPIAN) TUBES or OVIDUCTS • Tubes transporting secondary oocyte to site of fertilization and zygote to uterus UTERUS (womb) • Site of embryo implantation and fetal development VAGINA • Passageway from cervix of uterus to exterior VULVA (pudendum) • Collective name for female external genitalia MAMMARY GLANDS • Considered part of integumentary and reproductive systems

Oogenesis (Female Reproductive System)

Oogenesis is the formation of gametes in the ovaries. BEGINS BEFORE BIRTH: • Oogonia complete mitosis during fetal development, develop into primary oocytes • Primary oocytes (diploid; 2n) begin meiosis, but are arrested in Prophase I (until puberty) • At birth: 200,000- 2,000,000 primary oocytes in primordial follicles within each ovary

Name/Describe the Ovarian follicles

Ovarian follicles lie within the cortex of the ovaries. They are like little bags that surround developing oocytes. They consist of the developing oocyte and the cells that surround it (single layer = follicular cells; multiple layers = granulosa cells) PRIMORDIAL FOLLICLE • Single layer of cells surrounding primary oocytes PRIMARY FOLLICLE • Clear zona pellucida (glycoprotein layer), multilayered granulosa cells, and theca folliculi cells (organized outer layer) SECONDARY FOLLICLE • Corona radiata (inner layer of granulosa cells attached to zona pellucida), antrum (fluid-filled space), and theca interna (secretes estrogens) and theca externa (outer capsule-like layer) GRAAFIAN (MATURE) FOLLICLE • Larger than secondary follicle with much larger antrum. Ruptures and ovulates CORPUL LUTEUM • Remnants of Graafian follicle after ovulation, produces hormones CORPUS ALBICANS • Degenerated corpus luteum becomes a fibrous scar if fertilization does not occur

Describe the layers of Uterine Wall

PERIMETRIUM: Outer protective (serous) layer. MYOMETRIUM: Three smooth muscle layers important during labor. ENDOMETRIUM: Inner mucosa layer • Functional layer (Stratum functionalis) - next to lumen. Sloughs off each month if fertilization does not occur. • Basal layer (Stratum basalis) - divides to produce a new functional layer after menstruation each month.

Describe the role of Androgens during prenatal development and puberty in males

PRENATAL DEVELOPMENT: Androgens influence development of male reproductive system. PUBERTY: Androgens cause development/enlargement of male sex organs and muscular/skeletal growth that results in masculine secondary sexual characteristics. • SECONDARY SEXUAL CHARACTERISTICS: Traits distinguishing males from females that do not have a direct role in reproduction. - MALES: Wide shoulders, narrow hips, facial + chest hair, thickening of skin, enlargement of the larynx and deepening of the voice. Androgens also influence spermatogenesis in males, and sex drive (libido) in males and females

Follicular Development (Female Reproductive System)

PUBERTY: ~400,000 primary oocytes remain. Each month LH and FSH cause a few primordial follicles containing primary oocytes to develop. • First: primordial follicle --> primary follicle (granolosa cells form) • Then: Primary follicle --> secondary follicle (antrum and capsule form) • A single primary oocyte in a secondary follicle will become dominant and develop into a large mature Graafian follicle, and complete meiosis I (becomes a secondary oocyte- haploid; n) just prior to ovulation • Completion of meiosis I produces a secondary oocyte and 1st polar body (unequal cytoplasm distribution) • Ovulated as secondary oocyte (haploid; n) and corona radiata (innermost layer of granulosa cells) Meiosis II - only if penetrated by sperm in uterine tube Yields an ovum and a second polar body Fusion of nuclei = fertilization, forms diploid zygote

Explain how polyspermy is blocked (i.e. what keeps mutiple sperm from penetrating the oocyte)

Polyspermy block - fast and slow reactions prevent another sperm from penetrating the oocyte. The first sperm cell to reach the oocyte plasma membrane binds to a protein (integrin α6β1 rc) on the oocyte plasma membrane. • FAST-BLOCK TO POLYSPERMY: Binding triggers rapid depolarization of the oocyte plasma membrane and other sperm cannot attach. • SLOW-BLOCK TO POLYSPERMY: Depolarization triggers the release of intracellular Ca2+, which causes exocytosis of molecules that denature/harden the zona pellucida, denaturing ZP3. Without ZP3 other sperm cannot bind to and penetrate the oocyte. Zona pellucida separates further from oocyte.

Gonads

Produce germ cells called gametes Sexual reproduction involves gonads that produce gametes and sex hormones Male gonad is testes, gamete is sperm Female gonad is ovary, gamete is secondary oocyte

Describe the Testes (what they produce and how regulated)

Produce sperm & secrete hormones Paired male gonads in SCROTUM • Loose skin & underlying hypodermis supports testes in 2 internal sacs that hang from root of penis.

Acrosomal Reaction

Release of acrosomal enzymes to digest path through zona pellucida to plasma membrane of oocyte -Hydrolitic enzymes in the acrosome break down the jelly barrier

Male reproductive system of ducts

Reproductive ducts store and transport sperm DUCTS OF THE TESTES • Sertoli cells secrete fluid that pushes sperm into seminiferous tubule lumen and through a series of ducts leading to ductus epididymus EPIDIDYMIS: lies along posterior border of each testis • Sperm move through the tightly coiled ductus epididymis • Functionally epididymis is the site of sperm maturation where sperm develop motility and ability to penetrate the secondary oocyte. Also stores sperm. DUCTUS DEFERENS(vas deferens): ~18" long • Ascends, loops over ureter, and ends at dilated ampulla • Stores sperm and conveys them to urethra during sexual arousal. EJACULATORY DUCTS • Union of ductus deferens and duct of seminal vesicles • Empties sperm and seminal fluid into prostatic urethra URETHRA • Shared by reproductive and urinary systems • Prostatic, membranous, and spongy urethra • Ends at the external urethral orifice

What do the ovaries produce?

SECONDARY OOCYTES: Follicles in different stages of development surround and nourish developing oocytes within the ovaries ALSO PRODUCE/SECRETE HORMONES: Progesterone, estrogen, inhibin and relaxin

Placenta

SITE OF EXCHANGE OF NUTRIENTS AND WASTES BETWEEN THE MOTHER AND EMBRYO/FETUS • Fetal portion formed by the chorion • Maternal portion formed by endometrium • Functions for O2/CO2 exchange, protective barrier, stores nutrients, produces several hormones to maintain pregnancy • After the birth of the baby, the placenta detaches and becomes the "afterbirth".

Seminal Fluid

Secretions of the seminal vesicles, prostate, and bulbourethral glands. • Provides sperm with a transportation medium, nutrients, and protection from acidic pH.

Describe the Postovulatory Phase in the Female Reproductive Cycle

Secretory, Luteal Phase (Day 15-28) AFTER OVULATION, THE MATURE FOLLICLE LEFT WITHIN THE OVARY (INFLUENCED BY LH) BECOMES THE CORPUS LUTEUM. The corpus luteum secretes estrogen, progesterone, & inhibin If fertilization occurs, the chorion of developing embryo will secrete hCG (human chorionic gonadotropin- detected in urine pregnancy tests) and the corpus luteum will persist. • Progesterone, estrogen, and inhibin levels remain high • The endometrium is maintained and continues to grow/thicken If fertilization does NOT occur, the corpus luteum will degenerate within 10-12 days, forming the corpus albicans. • Progesterone, estrogen, and inhibin levels quickly decline • FSH levels increase (lack of negative feedback) • The menstrual phase begins again

Describe how sperm move from the vagina, through the uterus, and into uterine tubes

Sperm move from vagina, through uterus (<1%) and into uterine tubes (<200) • Sperm use flagella to swim from vagina into the cervical canal. • Smooth muscle contractions (aided by prostaglandins) in uterus and uterine tube moves sperm toward female gamete. • CAPACITATION occurs as they move through (changes in sperm that make it capable of penetrating the oocyte) - Tail beats more vigorously and plasma membrane around head weakens

Describe Penetration of the Oocyte

Sperm must go through: CORONA RADIATA: Loose matrix of cells surrounding oocyte Strong tail movements propel the sperm cell forward ZONA PELLUCIDA: Glycoprotein layer surrounding oocyte • Sperm cell cap molecule binds to a protein (ZP3) on zona pellucida and triggers the ACROSOMAL REACTION.

Completion of Fertilization (what processes constitute fertilization and result in the zygote?)

Sperm penetrating oocyte triggers completion of meiosis II by oocyte, producing second polar body and the haploid female pronucleus. Fusion of the male and female pronuclei constitutes fertilization and results in a diploid cell called a zygote.

State the function of flagella and the tail of the sperm cell

Sperm use flagella to swim from vagina into the cervical canal Strong tail movements propel the sperm cell forward

Describe how the testes are regulated

TEMPERATURE: Normal sperm production occurs at a 2-3 degrees below core body temperature. Regulated by CREMASTER MUSCLE: • Contract to elevate scrotum, bringing testes closer to warmth of pelvic cavity • Relax to move them further away for cooling

Male ducts, accessory glands, & supporting structures

TESTES: Paired male gonads in scrotum SYSTEM OF DUCTS: Epididymis, ductus deferens, ejaculatory ducts, and urethra ACCESSORY GLANDS: Seminal vesicles, prostate, and bulbourethral glands SUPPORTING STRUCTURES: Scrotum and penis

Parturition (Labor)

THE PROCESS BY WHICH THE FETUS IS EXPELLED FROM THE UTERUS THROUGH THE VAGINA (i.e. childbirth) Controlled by complex interactions of several hormones: • Rising levels of estrogens stimulate release of prostaglandins by placenta, which cause softening of the cervix • Estrogens also increase number of oxytocin receptors in uterine muscle fibers, enhancing oxytocin stimulation of uterine contractions by positive feedback cycle • Relaxin increases flexibility of pubic symphysis and helps dilate cervix • Oxytocin stimulates uterine contractions until the baby is delivered and the positive feedback cycle is broken.

Summarize Spermatogenesis

Takes 65-75 days 1. BEGINS WITH SPERMATOGONIA DIVISION (2n stem cells): • Spermatogonia begin mitosis at puberty • Some remain near basement membrane as undifferentiated stem cells (replace themselves). • Others move between Sertoli cells toward lumen, differentiating to become PRIMARY SPERMATOCYTES (diploid; 2n) 2. PRIMARY SPERMATOCYTE REPLICATES ITS DNA, THEN... 3. MEIOSIS PRODUCES 4 HAPLOID SPERMATIDS IN 2 PHASES: • Meiosis I: Homologous chromosomes separate. (2n --> n) -Forms: 2 secondary spermatocytes (haploid; n) • Meiosis II: Sister chromatids separate. -Forms: 4 spermatids (haploid; n) 4. SPERMIOGENESIS: Spermatids develop into sperm cells. • Sperm cells (spermatozoa) move into lumen of tubule

Describe Testosterone's role in the male reproductive system

Testosterone is converted to another androgen called DHT (dihydrotestosterone) in some target cells. Testosterone and DHT both bind to nuclear receptors and influence gene expression in target cells.

Name the 4 phases of the Female Reproductive Cycle and when they occur

The female reproductive cycle consists of 4 phases, with accompanying hormonal, ovarian, and uterine changes during each. 1) MENSTRUAL PHASE (Day 1-5) 2) PREOVULATORY PHASE (Day 6-13) • Also called the Proliferative phase/Follicular phase 3) OVULATION (Day 14) 4) POSTOVULATORY PHASE (Day 15-28) • Also called the Secretory phase/Luteal phase

Briefly name/describe the cycles in the Female Reproductive Cycle

The female reproductive cycle consists of the ovarian cycle, the uterine cycle, and the hormonal changes that regulate them. OVARIAN CYCLE • Occurs in ovary during and after maturation of oocyte UTERINE CYCLE • Concurrent changes in endometrium of uterus to prepare to receive fertilized ovum and support its development • Each cycle takes around 28 days (24-35d)

Fetal Period

The fetal period (from week nine to birth) is primarily concerned with the growth and differentiation of tissues and organs that developed during the embryonic period.

Reproductive System

The male and female reproductive systems work together to produce offspring through sexual reproduction.

Birth control methods

The principal method of sterilization for females is TUBAL LIGATION (having their "tubes tied") - analagous to a vasectomy in males • Uterine tubes are cut and then sealed off • Alterative to surgical sterilization: Essure plugs inserted into uterine tubes promote the development of scar tissue, sealing off the uterine tubes from the uterus. HORMONAL METHODS (the pill, NuvaRing, patch, shot) • Estrogen & progesterone • Inhibit ovulation by suppressing FSH and LH. Estrogen levels do not slowly rise and there is no midcycle LH surge. (inhibits the release of the female gamete) • IUD (Intrauterine device) Inserted into the cavity of the uterus, can be copper or hormonal-based. • CONDOMS (barrier method) prevent sperm from gaining access to the uterine cavity and tubes. Protect against STDs.

Describe the vasectomy procedure. Does it interfere with testosterone production or libido?

The principal method of sterilization for males is vasectomy STERILIZATION: methods that intentionally leave a person unable to reproduce. IN A VASECTOMY, A PORTION OF EACH OF THE DUCTUS DEFERENS IS REMOVED & THE ENDS ARE SEALED. • Sperm production in testes continues, but sperm can no longer reach the urethra • Sperm degenerate and are destroyed by phagocytosis • Blood vessels remain intact, so testosterone is still produced and distributed normally in the body NO EFFECT ON LIBIDO, EJACULATION, ETC.

Fertilization

The process that results in the union of a male gamete with a female gamete.

Lactation

The secretion and ejection of milk from mammary glands Involves 2 hormones: PROLACTION • Secreted by anterior pituitary gland • Promotes milk synthesis and secretion • Inhibited by progesterone until maternal levels drop after delivery • Principal stimulus maintaining PRL secretion is suckling of baby stimulates stretch receptors, initiating nerve impulses from hypothalamus, causing release of PRL. OXYTOCIN • Suckling of baby stimulates stretch receptors, initiating nerve impulses from hypothalamus • Oxytocin secreted by posterior pituitary gland • Promotes milk ejection and contraction of myoepithelial cells to move milk from alveoli into mammary ducts, where it can be suckled.

Name/Describe the ligaments of the ovaries

The two ovaries are suspended on either side of uterus in peritoneal cavity, held in position by ligaments. BROAD LIGAMENT: Encloses ovaries and attaches them to pelvic wall. MESOVARIUM: Fold of the peritoneum that forms part of the broad ligament and further stabilizes the ovaries. OVARIAN LIGAMENT: Attaches the ovaries to the uterus. SUSPENSORY LIGAMENT: Attaches the ovaries laterally to the pelvic wall.

Define Fertilization

The union of the genetic material from a haploid sperm and haploid secondary oocyte to form a diploid zygote. Male and female pronuclei (n) come together to form a single nucleus (2n) Typically occurs in uterine tube 12 to 24 hours after ovulation. • Sperm are viable for ~48 hours after deposition in the vagina • Secondary oocytes are viable for ~24 hours after ovulation • Window for fertilization: ~3 days (2 days before + 1 day after ovulation occurs)

Role of Ducts, Accessory Sex Glands, & Supporting Structures

There are anatomically distinct reproductive organs for producing gametes, facilitating fertilization, and sustaining embryonic growth and development (females). DUCTS: store and transport gametes. ACCESSORY SEX GLANDS produce substances that protect gametes and facilitate their movement. SUPPORTING STRUCTURES assist in the delivery of gametes and the growth of the embryo during pregnancy.

How do the testes produce sperm?

They contain SEMINIFEROUS TUBULES that produce sperm during spermatogenesis. SEMINIFEROUS TUBULES CONTAIN 2 TYPES OF CELLS: 1) SPERMATOGENIC CELLS: sperm-forming cells. Begin sperm production at puberty 2) SERTOLI CELLS: supporting cells. Nourish and control movement of developing sperm cells for release into the lumen, and secrete inhibin to decrease rate spermatogenesis.

Describe the Uterine Tubes

Uterine tubes (or fallopian tubes/oviducts) extend laterally from uterus toward ovaries. • INFUNDIBULUM: distal funnel shape end of tube, open to serous fluid of peritoneal cavity • FIMBRIAE: fingerlike extensions lined with cilia that sweep the ovulated oocyte into the infundibulum • Ampulla: widest, longest portion, typically site of fertilization • Isthmus: short, narrow connection to uterus

State the general name for and describe the components of the female external genitals

VULVA • LABIA MAJORA: large folds of skin that enclose the medial components of the vulva. • LABIA MINORA: smaller protective folds of skin. • CLITORIS: small mass of erectile tissue • VESTIBULE: region between the labia minora. Contains: Vaginal orifice, external urethral orifice, vestibular glands (produce mucus), vestibular bulb (erectile tissue on either side of vaginal orifice)

What constitutes male infertility?

When <20 million sperm per mL in ejaculate

Describe the function of mammary glands

Within each breast is a mammary gland that functions in the production & ejection of milk (lactation). Modified sudoriferous gland that produces milk Lobules composed of milk-secreting alveoli (glands) separated by adipose tissue Myoepithelial cells contract to propel milk through ducts • Secondary tubules, mammary ducts, lactiferous sinuses, and lactiferous ducts drain milk to nipple

Hormones of Pregnancy

hCG: HUMAN CHORIONIC GONADOTROPIN • Secreted by chorion to maintain corpus luteum until about 4th month, when placenta produces enough progesterone and estrogens PROGESTERONE & ESTROGENS • Secreted initially by corpus luteum, then chorion, and later placenta • High estrogen level prepares myometrium for labor; progesterone ensures myometrium is relaxed and cervix tightly closed RELAXIN • Secreted initially by corpus luteum, and later by placenta • Increases the flexibility of pelvic ligaments and helps dilate cervix for delivery