THE MALE AND FEMALE REPRODUCTIVE SYSTEMSExercise 42 & 47

A&P 233

MALE REPRODUCTIVE SYSTEM

Produces male games (sperm cells) in the seminiferous tubules in the testes

Transports gametes to the female reproductive tract

Secretes testosterone

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SCROTUM

The testes sit in the scrotum Sac of skin and superficial fascia that hangs

outside the abdominopelvic cavity at the root of the penis

Contains paired testicles separated by a midline septum

Its external positioning keeps the testes 3C lower than core body temperature

WALL OF THE SCROTUM In the dermis, there is

a thin layer of smooth muscle known as the dartos muscle. Contractions of this muscle causes wrinkling of the skin.

The cremaster muscle is a thicker layer of skeletal muscle that lowers and raises the testes based on temperature.

INSIDE THE SCROTUM

A fibrous (tough connective tissue) capsule covers each testis called the tunica albuginea.

TESTICLE

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The tunica albuginea gives rise to septa (partitions) that divide the testis into lobules (about 250)

Each lobule contains 3 or 4 highly coiled seminiferous tubules

These converge to become rete testis which transport sperm to the epididymis

CELLS OF THE TESTIS

Interstitial cells: produce testosterone Spermatogonia: reproduce by mitosis to

produce primary spermatocytes. Sustentacular (Sertoli) cells: form blood

testis barrier (BTB), supplies nutrients to developing sperm, protect. (Also called nurse cells)

Primary spermatocytes divide by meiosis to form secondary spermatocytes which are located closer to the lumen of the tubule.

The process of sperm formation from spermatogonia to sperm cells is called spermatogenesis

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SEMINIFEROUS TUBULES

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SEMINIFEROUS TUBULES HISTOLOGY

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SPERMATOGENESIS

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SPERMIOGENESIS: SPERMATIDS TO SPERM

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SPERM Sperm have three major regions

1. Head :contains DNA and has a helmet-like acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg

2. Midpiece: contains mitochondria spiraled around the tail filaments

3. Tail :a typical flagellum produced by a centriole

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EPIDIDYMIS

Epididymis: Storage and maturation area for sperm

Its head joins the efferent ductules and caps the superior aspect of the testis

The duct of the epididymis has stereocilia that: Absorb testicular fluid Pass nutrients to the sperm

Nonmotile sperm enter, pass through its tubes and become motile (propelled by peristalsis)

Upon ejaculation the epididymis contracts, expelling sperm into the ductus deferens

EPIDIDYMIS HISTOLOGY

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SPERMATIC CORD

Contains the structures running from the testicles to the pelvic cavity. Passes through the

inguinal canal Contents:

Vas Deferens Nerves Blood Vessels

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ACCESSORY GLANDS: SEMINAL VESICLES

Lie on the posterior wall of the bladder and secrete 60% of the volume of semen Seminal fluid:

Fructose and other carbohydrates: provides energy for the sperm.

As well as some protein, citrate and prostaglandins

Join the ductus deferens enlarges to form ampulla.

Each ductus deferens joins with the seminal vesicles which forms the ejaculatory ducts

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POSTERIOR BLADDER

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POSTERIOR BLADDER

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ACCESSORY GLANDS: PROSTATE GLAND

Doughnut-shaped gland that encircles part of the urethra inferior to the bladder

Plays a role in the activation of sperm Enters the prostatic urethra during

ejaculation Constitutes about 30% of semen. Prostatic secretions function to:

Buffer the vaginal and seminal acidity, raising the pH to about 7.5 and activating the sperm (pH of the vagina is about 3.5 – 4.0)

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BULBOURETHRAL GLANDS (COWPER’S GLANDS)

Pea-sized glands inferior to the prostate

Add lubricant to the seminal fluid

Seminal fluid consists of secretions from the seminal vesicles, prostate gland and bulbourethral glands.

Semen consists of seminal fluid plus the sperm cells from the testes.

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PENIS HISTOLOGY

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SPERM SUMMARY

Produced: Seminiferous tubules Stored: Epididymis Transported through epididymis by rhythmic

peristaltic contractions as they mature Epididymis Vas Deferens Ejaculatory duct

(ampulla of vas deferens fuses with duct of seminal vesicle “ejaculatory duct”) prostate prostatic urethra (then passes the bulbourethral gland) membranous urethra penile urethra

REVIEW QUESTIONS

What is the difference between mitosis and meiosis?

What are the results of meiosis?

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SPERMATOGENESIS

Spermatogenic stem cells of the seminiferous tubules give rise to sperm in a series of events Mitosis of spermatogonia, forming spermatocytes Meiosis forms spermatids from spermatocytes Spermiogenesis: spermatids form sperm

VASECTOMY

Male sterilization Cutting and tying of

the two ductus deferens.

Prevents sperm from traveling from the testes to the spermatic cords

Sperm is reabsorbed by the body

THE FEMALE REPRODUCTIVE SYSTEMExercise 47

A&P 233

FEMALE REPRODUCTION Unlike males, who

are able to produce sperm cells throughout their reproductive lives, females produce a finite number of egg cells.

During early fetal development germ cells migrate into the ovaries and differentiate into oogonia

GROSS ANATOMY The ovaries are solid,

ovoid structures, about 2 cm in length and 1 cm in width.

Like the testes, they develop from embryonic tissue along the posterior abdominal wall, near the kidneys.

Accessory organs include the uterine tubes, uterus, and vagina.

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OVARIES

Each follicle consists of an immature egg called an oocyte

Cells around the oocyte are called: Follicle cells (one cell layer thick)

Stimulated to mature by FSH from the pituitary gland Granulosa cells (when more than one layer is

present) Thecal cells: Cells in the ovarian stroma

Thecal & granulosa cells work together to produce estrogen

A protective layer of glycoprotein forms around the egg called the zona pellucida

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OVARY HISTOLOGY

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Zona pellucida

1° Oocyte(arrested in prophase I)

Granulosa cells

Thecal cells

Nucleus

Primary Follicle

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SECONDARY FOLLICLEFluid-filled antrum

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GRAAFIAN FOLLICLE

Fluid filled antrum

Granulosa cells

Oocyte 2°

Corona radiata

Stalk

Zona pellucida

OVARIAN FOLLICLES

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FOLLICLE DEVELOPMENT

1. Primordial follicle: one layer of squamous-like follicle cells surrounds the oocyte

2. Primary follicle: one or more layers of cuboidal granulosa cells enclose the oocyte

3. Secondary follicle: has a fluid-filled space between granulosa cells that coalesces to form a central antrum

4. Graafian follicle: secondary follicle at its most mature stage that bulges from the surface of the ovary

5. Corpus luteum : ruptured follicle after ovulation

CORPUS LUTEUM

After ovulation, the remains of the follicle are transformed into a structure called the corpus luteum.

If a pregnancy occurs, it produces progesterone to maintain the wall of the uterus during the early period of development.

CORPUS ALBICANS

If fertilization does not occur, the corpus luteum will begin to break down about 2 weeks after ovulation.

Degeneration occurs when fibroblasts enter the corpus luteum and a clump of scar tissue forms called the corpus albicans.

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UTERINE TUBES (FALLOPIAN TUBES)

Receive the ovulated oocyte and provide a site for fertilization

The ampulla ends in the funnel-shaped, ciliated infundibulum containing fingerlike projections called fimbriae

Expand distally around the ovary forming the ampulla

Empty into the superolateral region of the uterus via the isthmus

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UTERINE TUBES (FALLOPIAN TUBES)

Fimbriae sweep oocyte into tube, cilia & peristalsis move it along, sperm reaches oocyte in ampulla, fertilization occurs within 24 hours after ovulation & zygote reaches uterus about 7 days after ovulation

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FALLOPIAN TUBE HISTOLOGY

Cilia sweep egg/zygote toward the uterus

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UTERUS

Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder

Body: Major portion of the uterus Fundus: Rounded region superior to the

entrance of the uterine tubes Isthmus: Narrowed region between the body

and cervix

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UTERUS

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UTERINE HISTOLOGY

Endometrium Simple columnar epithelium Stroma of connective tissue and endometrial glands

Stratum functionalis: Shed during menstruation

Stratum basalis: Replaces stratum functionalis each month

Myometrium 3 layers of smooth muscle

Perimetrium Visceral peritoneum

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UTERINE HISTOLOGY

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ENDOMETRIUM

Simple columnar epithelium

Endometrial glands

ENDOMETRIUM Proliferative phase:

glands and blood vessels scattered throughout the functional zone with little or no branching.

New glands form and endometrium thickens.

Secretory phase: glands are enlarged and have branches. Preparing the endometrium for implantation

If no implantation then endometrium breaks down and menstruation begins.

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CERVIX

Narrow lower neck of the uterus which projects into the vagina inferiorly

Cervical canal – cavity of the cervix that communicates with: The vagina via the external os The uterine body via the internal os

Cervical glands secrete mucus that covers the external os and blocks sperm entry except during midcycle

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Fornix

Endocervical canal

OVARIAN AND UTERINE CYCLES

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FEMALE: LATERAL VIEW

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VAGINA

Thin-walled tube lying between the bladder and the rectum, extending from the cervix to the exterior of the body

Wall consists of three coats: fibroelastic adventitia, smooth muscle muscularis, and a stratified squamous mucosa

Mucosa near the vaginal orifice forms an incomplete partition called the hymen

Vaginal fornix: upper end of the vagina surrounding the cervix

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FEMALE EXTERNAL GENITALIA

Vulva: all external female genital structures Mons pubis: fatty pad over the pubic symphysis Labia majora & minora: folds of skin encircling

vestibule where find urethral and vaginal openings

Clitoris: small mass of erectile tissue Bulb of vestibule: masses of erectile tissue just

deep to the labia on either side of the vaginal orifice

Perineum: Area between the vagina and anus

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FEMALE EXTERNAL GENITALIA

Perineum

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BARTHOLIN’S GLANDS

(AKA: VESTIBULAR GLANDS) The Bartholin's glands are located on each side

of the vaginal opening. They secrete fluid that

helps lubricate the vagina. Sometimes the ducts of

these glands become obstructed. Fluid backs up into the gland

and causes swelling (Bartholin's cyst)

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MAMMARY GLANDS

Modified sweat glands that produce milk (lactation) Amount of adipose determines size of breast Milk-secreting glands open by lactiferous ducts at

the nipple Areola is pigmented area around nipple Suspensory ligaments suspend breast from deep

fascia of pectoral muscles (aging & Cooper’s droop) Mammary line is a thickened ridge of embryonic

tissue that extends from the axilla to the groin.

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BREAST

Prolactin from the pituitary gland stimulates the synthesis of milk

Oxytocin from the posterior pituitary gland stimulates milk ejection

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LYMPHATIC DRAINAGE

Lymph nodes draining the breast are located in the axilla.

TODAY’S LAB

ID structures on the models View slides