Male Reproductive System Anatomy

Reproductive System Overview

• Consists of primary sex organs (gonads) and accessory reproductive organs.
• Gonads produce gametes (sex cells) and secrete hormones.
• Male gonads are testes which produce sperm.
• Female gonads are ovaries which produce ova or eggs.
• Accessory reproductive organs include ducts and external genitalia.

Male Reproductive System

• Testes: there are two of them
• The duct system moves in order from the testis to the penis

Duct System Details

• Epididymis: think epidermis – outside, it is the worm-looking thing on the outside of the testis, there are two of them
• Vas deferens: the long pink tube going up from the testis, there are two of them
• Ejaculatory duct: the worm-looking thing in front of the urinary bladder, there are two of them
• Urethra connects into it

Testes Coverings

• Tunica Albuginea ("white coat"): the capsule that surrounds each testis for protection.
• Septa divides the testes into lobules, where septa refers to the wall.
• The extensions of the capsule extend into the testis.
• Each lobule contains 1-4 seminiferous tubules.

Interior of Testes - Seminiferous Tubules

• Sperm-forming factories
• Tightly coiled structures
• Leydig cells produce androgens such as testosterone.
• Sperm doesn't stay once made, instead empties into the rete testis
• Sperm then travels through rete testis before entering the epididymis.

Duct System - Epididymis

• Comma-shaped and filled with a tightly coiled tube.
• Positioned superiorly (on top) and extends down the posterior lateral side of testes diagonally.
• The tubes inside are 6 m long but are packed into a small space.
• Stores and matures sperm for a minimum of 20 days.
• Expels sperm via peristalsis of muscles in walls to vas deferens.

Duct System - Vas Deferens

• Also known as Ductus Deferens.
• Carries sperm from the epididymis to the ejaculatory duct, which unites with the urethra.
• Passes over the bladder.
• Transports sperm to the ejaculatory duct through peristalsis.
• Enclosed with blood vessels and nerves in a connective tissue sheath called the spermatic cord.

Duct System - Urethra

• Extends from the base of the urinary bladder to the tip of the penis.
• Sperm enters frome the ejaculatory duct
• Carries both urine and sperm, NEVER at the same time.

Regions of the Urethra

• Prostatic urethra: attached to the bladder, running through the prostate gland.
• Membranous urethra: begins from the prostatic urethra to the start of penile urethra.
• Spongy (penile) urethra: runs along the length of the penis, externally from body.

Accessory Organs (Male)

• Seminal vesicles (2)
• Prostate gland (1)
• Bulbourethral glands (2)

Male External Genitalia

• Penis
• Scrotum

Seminal Vesicles

• Located at the base of the bladder.
• Secretes a thick, yellowish fluid that makes up 60% of semen.
• Secretion contains fructose (sugar), vitamin C, and prostaglandins.
• Nourishes and activates sperm.

Prostate Gland

• Encircles the upper part of the urethra (prostatic).
• Secretes a milky fluid to help activate the sperm.
• Enters urethra through small ducts.

Bulbourethral Glands

• Pea-sized glands inferior to the prostate.
• Produce thick, clear mucus.
• Is the first fluid to pass down the penile urethra.
• Cleanses the urethra of acidic urine.
• Serves as a lubricant.

Semen Composition

• A combination of sperm and secretions from seminal vesicles, prostate gland, and bulbourethral glands.

Advantages of Accessory Gland Secretions

• Elements of semen supply energy and enhance sperm motility.
• Alkalinity of semen neutralizes the vaginal environment's acidity.
• Acidity in the vagina protects the female from bacterial growth.
• Semen inhibits bacterial multiplication due to factors that keep the female protected.

Penis

• Serves to deliver sperm into the vaginal canal.
• Contains spongy erectile tissue around urethra.

Regions of the Penis

• Shaft
• Glans penis - enlarged tip
• Prepuce (foreskin) - folded cuff of skin around distal end, which may be removed by circumcision.

Scrotum

• Divided sac of skin outside the abdomen.
• Testes are maintained at 3ºC lower than normal body temperature for sperm viability.

Female Reproductive System

• Ovaries

Female Duct System

• 2 fallopian tubes (also referred to as the uterine tubes)
• Uterus
• Vagina

Ovaries

• Composed of ovarian follicles
• Made up of 2 parts:
  • Oocyte (fancy word for egg)
  • A series of Granulosa Cells (surrounds the outside of the oocyte almost like a little shell)

Ovarian Cycle

• The ovarian cycle takes 28 days
• The follicular phase contains a primary follicle which contains an immature oocyte with a single layer of granulosa cells.
• The secondary follicle is a growing follicle with increasing amounts of granulosa cells and a maturing oocyte.
• The vesicular follicle has a fluid filled region called an antrum and a maturing oocyte is ready to be ejected from ovary
• The luteal phase occurs when the oocyte and follicle are mature leading to ovulation; the follicle ruptures, releasing the egg out of the ovary and into the fallopian tube
• Corpus luteum is a ruptured follicle which is transformed into a structure which produces hormones.
• The corpus luteum degenerates by day 28 if no pregnancy occurs.

Hormonal Control of Ovarian Cycle

• Ovarian cycle is controlled by 2 of the anterior pituitary hormones
• Follicle-Stimulating hormone (FSH) stimulates follicular development (follicular phase) Luteinizing hormone (LH) stimulates ovulation (luteal phase)

Fallopian Tubes

• Attached to uterus and receives the ovulated oocyte.
• Fertilization occurs inside the tubes and are about 10 cm long.
• There is little actual contact between the fallopian tubes and ovaries.

Fimbriae

• Finger-like projections at the distal end of fallopian tubes that receive oocyte.
• Create fluid currents to move oocyte towards uterus.
• Some eggs get lost in the body cavity.

Uterus

• Located between bladder and rectum.
• Functions to retain and nourish a fertilized egg.

Three Regions of the Uterus

• body – main body
• fundus – area where the fallopian tube enters
• cervix – narrow outlet that protrudes into vagina

Walls of the Uterus

• Perimetrium is the outer layer (Peri = around)
• Myometrium is the middle layer of smooth muscle responsible for uterine contractions during delivery (Myo = muscle).
• Endometrium is the inner layer and a mucous membrane that becomes blood rich (Endo = inside).
  • Allows for implantation of a fertilized egg
  • Shed if no pregnancy occurs (menses)

Vagina

• Extends from cervix to exterior of body.
• Behind bladder and in front of rectum.
• Serves as the birth canal.
• Receives the penis during sexual intercourse.
• The hymen partially closes the vagina until it is ruptured.

Female External Genitalia (Vulva)

• Mons pubis: a fatty area overlying the pubic bone and covered with pubic hair after puberty..
• Labia: skin folds
  • Labia majora: outer folds
  • Labia minora: inner folds
• Vestibule: enclosed by labia minora, surrounds several things
  • Urethral orifice: opening to the urethra
  • Vaginal orifice: opening to the vaginal canal
  • Orifices of the great vestibular glands: produces mucus for lubrication
• Clitoris: contains erectile tissue that swells with blood.
• Perineum: diamond-shaped marked by the anterior labial folds, posterior anus and sit bones.

Mammary Glands

• Present in everyone, but function to produce milk in only those with estrogens.
• Modified sweat glands stimulated by sex hormones to increase size at puberty.
• Areola includes a central pigmented area and nipple with 15-25 internal lobes radiate around nipple

Mammary Structures

• Lobule: smaller chamber within the lobe.
• Alveolar glands (alveoli): produce milk within the lobules.
• Lactiferous ducts: connect alveolar glands to nipple.

Menstrual (Uterine) Cycle

• Cyclic changes of the endometrium
• Menstrual phase: the superficial functional layer of endometrium is sloughed off and flows through vagina (days 1-5)
• Proliferative phase: basal layer regenerates the functional layer of the endometrium (days 6-14)
• Secretory phase: endometrium increases blood supply and readies for implantation (days 15-28)

Estrogens production in ovaries.

• Increasing amounts are products through an increasing numbers of granulosa cells in secondary follicles.
• This stimulates the proliferative phase.

Progesterone

• Production is by the corpus luteum.
• Helps in implantation of an embryo in the uterus.
• Helps maintain pregnancy and prepare breasts for milk production.

Hormonal Cycle Control Summary

• Ovarian and menstrual cycles are controlled by hormones.
• Ovarian cycle control is anterior pituitary
  • FSH for follicular phase (follicular development)
  • LH for luteal phase (ovulation)
• Menstrual cycle involves 2 main hormones
  • estrogen = Proliferative phase (increases endometrium) – an ovarian hormone - comes from the granulosa cells
• progesterone = prepares endometrium for implantation - comes from the corpus luteum if the egg gets fertilized

Contraception Overview

• Contraception is also called birth control and is any method to prevent pregnancy.
• Understanding the failure rate is important when choosing a contraceptive.
• Interference in the reproductive process occurs in different ways among the available products.

Further Contraceptive Details

• Birth control pills are widely used and taken daily; failure rate is less than 6%.
  • Contains tiny amounts of estrogens and progesterone.
  • Tricks body to thinking it is pregnant, therefore ovaries do not ovulate.
  • A menstrual cycle still occurs, but the flow is reduced.
• Morning After Pills (MAP) are emergency contraception.
  • Taken within 5 days of unprotected intercourse or contraceptive failure.
  • Contains ingredients that disrupt hormonal signals of female to temporarily delay ovulation
  • Failure rate of approx. 10% Abortion pills induce miscarriage and failures occur 2% of the time.
  • Correct name is RU486 and is taken within 7 weeks of pregnancy to block progesterone

Progestin Use as Contraception

• Progestin is a synthetic progesterone that prevents ovulation by tricking the body into pregnancy
• Implants and Injections are available

Contraceptive Progestin Implants

• Flexible rod(s) are placed under the skin of the arm
• Release progestin over 3-yrer period
• Failure rate = 0.05% (there is no human error vs pills)

Contraceptive Progestin Injections

• Injectable every 3 months
• Depo-Provera
• Failure rate = 0.04%

Intrauterine Device (IUD)

• Plastic or metal device inserted in uterus to prevents implantation
• Newer version also secretes progestin preventing ovulation
• Failure rate = 0.1%

Vasectomy

• Cutting of vas deferens at the level of the testes to prevent transportation of sperm and has a < 0.2% Failure rate.

Tubal Ligation

• Involves cutting/cauterizing fallopian tubes to prevent transport and 0.2% Failure rate.
• Used by 33% of couples in North America

Coitus Interruptus

• Withdrawal of penis before ejaculation (pulling out)
• Is difficult to control
• Female must avoid intercourse during period of ovulation
• Requires daily records of body temp and vaginal mucus as ovulation clues -Failure rate = 4% - 20%, assuming proper procedure of the contraceptive method.

###Barrier Methods (Prevent Sperm Transport)

• Diaphragms (failure rate < 6%)
• Cervical caps (failure rate ~ 20%)
• Sponge (failure rate ~ 20%)
• Condoms (failure rate is 3%)

Contraception Sites of Interference

• No contraceptive is 100% effective
• It is important to know relative failure rates because some of terrible, some are okay, and some are excellent
• Knowing how these devices interrupts pregnancy/reproductive process