Pelvis and Contents

Pelvis and Contents

Reproductive Organs

Bones of the Pelvis

Pelvic / hip girdle

Function:

Attaches the lower limbs to spine

Supports the viscera of the pelvis

Transmits the weight of the upper body

Contents:

Paired hip bones (coxal bone)

Unite with each other anteriorly and with the sacrum posteriorly

Bony pelvis:

Os coxae, sacrum and coccyx

Use lab work to learn bony landmarks of pelvis

Os Coxae

Each pelvic bone during childhood:

Ilium

Superior region

Ishium

Posteroinferior region

Pubis
Anterior region

True and False Pelves

Separated by the pelvic brim

False Pelvis

Superior to the pelvic brim

Iliac blades

contains abdominal organs

attachment for muscles and ligaments to body wall

True Pelvis

Inferior to the pelvic brim

Space contains

part colon

rectum

bladder

uterus/ovaries (females)


Pelvic Diaphragm

levator ani and coccygeus muscles

Supports pelvic organs

Seals inferior opening of bony pelvis

Lifts to help release feces during defecation

Sexual Dimorphism

Females

Tilted forward

Cavity is broad, shallow

Pelvic inlet oval and outlet round

Bones are lighter, thinner

Pubic angle larger

Ischial tuberosities shorter, more everted

Coccyx more moveable, straighter

Males

Cavity is narrow, deep

Smaller inlet and outlet

Bones heavier, thicker

Pubic angle more acute

Ischial tuberosities longer, face more medially

Coccyx less moveable, more curved

Perineum

Anus and external genitalia

Diamond shaped

Pubic symphysis anteriorly

Ischial tuberosities laterally

Coccyx posteriorly

Females:

External genitalia

Anus

Males:

Scrotum

Root of penis

Anus 

Embryonic Development of the Sex Organs

Begin at week 5 as masses of gonadal ridges

Develop into the gonads

Sexually indifferent!

Both ducts are present in embryo, but only one develops:

Male

Mesonephric (Wolffian) ducts

Vas deferens, epididymis

Female

Paramesonephric (Müllerian) ducts

Uterus, oviduct, vagina

External genitalia develops from same structures

Embryonic structure Male Female

Labioscrotal swelling Scrotum Labia major

Urethral folds Penile Urethra Labia minor

Genital tubercle Penis Clitoris


Descent of the Gonads

Male Development:

Testes partially descend at 3 months, finish at 7 months

Enter the scrotum

Vaginal process

Outpocketing of the peritoneal cavity

Eventually closes off

Forms tunica vaginalis

Gubernaculum

Fibrous cord

Extends from the testis to floor of scrotal sac

Final teste descent:

Shortening of gubernaculum

Increase in intra-abdominal pressure

Testosterone stimulation

Descent of the Gonads

Female Development

Descend only into the pelvis

Broad ligament blocks further descent

Gubernaculum

Guides ovaries

Attached to labia major

Becomes:

Round ligament of the uterus (inferior portion)

Ovarian ligament (superior portion)

Vaginal process

Outpocketing of peritoneum guides descent

Puberty

Between ages 10 and 15

Reproductive organs grow to their adult size

Reproduction becomes possible

Changes occur due to the increase in reproductive hormones in each individual

Testosterone in males

Estrogens in females

Dimporhism at Puberty

Males

Age 13

Enlargement of the testes and scrotum

Secondary sex characteristics

Appearance of pubic, axillary, and facial hair

Enlargement of larynx

Oily skin 

Increase in body size and musculature

Females 

Age 11

Budding of breasts

Secondary sex characteristics

Increase in subcutaneous fat (hips and breasts)

Widening and lightening of the bones

Oily skin

Hair in pubic and axillary region

Menarche

Menstruation

Happens 1-2 years later

Reproductive System

Overall function is to produce offspring

Genitalia = sex organs

Primary = Gonads

Ovaries, testes

Produce the sex cells / gametes

Eggs, sperm

Secrete sex hormones

Secondary = Accessory

Glands, ducts, external genitalia

Nourish and transport of gametes

Male Reproductive System

Primary sex organ

Gonads = testes

Lie in the scrotum

Sperm-producing

Secondary sex organs

External Genitalia

Penis

Scrotum

Ducts

Epididymis

Efferent ductules

Duct of epididymis

Vas deferens

Ejaculatory duct



Urethra



Glands

Seminal vesicle

Prostate

Bulbourethral

Scrotum

Sac of skin and fascia

Hangs at the root of the penis

Contains the testes

Septum in midline divides right and left halves

Muscles:

Dartos

Inside skin of scrotum

Smooth muscle

Responsible for wrinkling of scrotal skin (warms)

Cremaster

Extends into scrotum from spermatic cord

Fibers from internal oblique

Skeletal muscle

Responsible for elevating and lowering the testes (warming and cooling)

Testes

Lie within the scrotum

Tunica vaginalis

Light sac partly covering each testes

Tunica albuginea

Fibrous capsule of the testes

Deep to tunica vaginalis

Divides testes into lobules

Lobules contain seminiferous tubules

Reproductive Duct System

Seminiferous tubules

“sperm factories”

Location of spermatogenesis

Converge into…….

Tubulus rectus

Straight tube that conveys sperm into….

Rete testis

Lead to the……

Efferent ductules

Lead to epididymis ….

Reproductive Duct System

Epididymis

Site of sperm maturation

Smooth muscle layer leads to ejaculation

Contains:

Head 

Contain the efferent ductules

tube from rete testes to duct of epididymis

Ciliated simple columnar epithelium

Body and Tail

Duct of epididymis

Highly coiled

Leads into the vas deferens

Pseudostratified columnar epithelium with stereocilia

Resorb testicular fliud

Transfer nutrients and secretions to sperm stored in the epididymis

Reproductive Duct System

Vas Deferens (Ductus Deferens)

Stores and transports sperm during ejaculation

Runs from epididymis to ejaculatory duct

ED then runs within the prostate gland and empties into the prostatic urethra

Layers:

Pseudostratified epithelium

Lamina propria

Thick muscularis

Adventitia

Vasectomy

Cut vas deferens, close off ends

Sperm STILL produced, but cannot exit the body

Reversible sometimes!

Reproductive System

Spermatic Cord

Collective name for structures associated with the scrotum

Passes through inguinal canal

Includes

Vas Deferens

Testicular arteries and veins (pampiniform plexus)

Lymphatic vessels

Cremaster muscle fibers

Nerves

Cell Division

Mitosis

Events in which replicated DNA of original cell is divided into 2 new cells

Cell division with chromosome duplication and division à2 daughter cells = parent

Have Diploid = 2n number of chromosomes

Occurs in body (somatic) cells

Meiosis = Reductional division

Events that reduce the number of chromosomes (1/2 of the parent)

Have Haploid = n number of chromosomes

Occurs in sex cells
Spermatogenesis

Production of sperm

Stages:

Stem cells = Spermatogonia (2n)

Mitosis

Formation of 2 daughter cells

Type A become precursor cells (2n)

Type B become primary spermatocytes (2n)

Meiosis

Primary spermatocytes undergo Meiosis I

2 secondary spermatocytes (n)

Secondary spermatocytes undergo Meiosis II

4 spermatids (n)

Spermiogenesis

Spermatids differentiate into sperm

Sperm cell (spermatozoan)

Head (acrosome), tail and midpiece

Controlled by FSH (pituitary gland) and testosterone (testes)

Within Seminiferous Tubules

Sustentacular cells (Sertoli cells)

Surround the spermatogenic cells in the lumen

Provide nutrients to spermatogenic cells

Move cells toward tubule lumen

Secrete testicular fluid

Phagocytize cytoplasm shed by developing spermatids

Secrete Androgen-binding protein (concentrates testosterone)

Secrete Inhibin (hormone slows rate of sperm production)

Blood-testis barrier

In tight junctions between the sustentacular cells

Prevent escape of membrane antigens from sperm into the bloodstream

Within Seminiferous Tubules

Myoid cells

Layers of smooth muscle cells

Contract to squeeze sperm thru tubules and out of testis

Interstitial cells (Leydig cells)

Make and secrete male sex hormone (androgens)

In CT between tubules

Accessory Glands

Seminal Vesicles (2)

Lie on posterior surface of the bladder

Joins the vas deferens to form an ejaculatory duct

Contracts during ejaculation to empty

Secretion contains:

Fructose to nourish sperm

Prostaglandins to stimulate contraction of the uterus

Suppress immune response in females

Sperm motility enhancers

Enzymes that clot ejaculated semen in vagina, then liquefy it so sperm can swim out

Accessory Glands

Prostate gland

Inferior to bladder, anterior to rectum

Encircles the first part of the urethra

Contracts during ejaculation

Secretion contains:

Substances that enhance sperm motility

Enzymes that liquefy ejaculated sperm

Bulbourethral gland (2)

Inferior to prostate gland

Within urogenital diaphragm

Empties into spongy urethra

Produce a mucus

Neutralize urine in urethra

Lubricate semen for passage

Penis

Male external genitalia

Delivers sperm into the female reproductive tract

Anatomy:

Root

Attached end

Crura

Anchored to pubic arch, covered by ischiocavernosus muscle

Bulb

Secured to urogenital diaphragm

Body / Shaft

Free; not attached

Glans penis

Enlarged tip

Prepuce / Foreskin

Loose cuff around glans

Spongy urethra

Tube within penis

Penis

Erectile bodies

3 cylindrical bodies around the spongy urethra

Thick tube covered by DCT

Filled with smooth muscle, CT, and vascular spaces

Corpus spongiosum

Midventral erectile body

Distally forms the glans penis

Proximally forms the bulb of the penis

Corpora cavernosa

Paired, dorsal erectile bodies

Proximal ends are the crura of the penis (crus)

Covered by ischiocavernosus muscle

Make up most of the mass of the penis

Penis Innervation and Vasculature

Arterial supply

Branches of internal pudendal

Innervation

Branches of pudendal from sacral plexus provides sensory innervation

Parasympathetic

Engorgement of blood in erectile bodies = erection

Sympathetic

Contraction of smooth muscle in ducts and glands and bulbospongiosum muscle = ejaculation

Autonomic from inferior hypogastric plexus

Female Reproductive System

Primary Sex Organs

Ovaries = gonads

Secondary Sex Organs

External Genitalia = vulva

Labia major + minor

Mons pubis

Clitoris

Ducts

Uterine tube = oviducts

Vagina

Glands

Greater vestibular gland

Anatomy

Ovaries (2)

Produce and store ova (eggs)

Produce estrogen

Tunica albuginea

Fibrous capsule that surrounds the ovary

Germinal epithelium

Covers the tunica albuginea

Mesothelium

Anatomy

Ovaries

Held in place by mesentery and ligaments made of peritoneum

Ligaments

Broad ligament

Supports uterus and oviducts

Suspensory ligament

Attaches ovaries to lateral pelvic wall

Ovarian ligament

Anchors the ovary to the uterus medially

Round ligament

Part of broad ligament

Attaches uterus to labia majorum

Oogenesis: production of eggs (ova)

Stem cells = oogonia undergo Mitosis

All of female’s oogonia produced while fetus

Oogonia become oocytes

Oogonia begin Meiosis I are called primary oocytes (2n)

Meiosis I is stalled before birth and until ovulation

During ovulation, Meiosis I completed and Meiosis II begins

Once Meiosis II begins, primary oocytes now called secondary oocytes (n)

Meiosis II is completed when sperm penetrates plasma membrane of the egg

When Meiosis II is completed, secondary oocyte is now called ovum (egg)

Meiosis II results in 4 daughter cells

1 ovum and 3 polar bodies (degenerate)

Uterine Tubes

Also called oviducts, fallopian tubes

Begins laterally near ovary and ends medially at uterus

3 parts:

Infundibulum

Lateral, funnel shaped portion

Fimbrae on edges

Ampulla

Medial to infundibulum

Expanded portion

Site where fertilization occurs

Isthmus

Medial part of the tube

Layers

Visceral Peritoneum

Smooth Muscle

Ciliated simple columnar epitheliu

Movement of Ova

Through the oviduct

Receives oocyte after ovulation

Peristaltic waves

Cilia lining tube

Contains cells to nourish ova

Ectopic pregnancy 

Implantation of embryo outside of the uterus

Uterus

Function: 

Receive, retain, nourish fertilized egg (=zygote)

3 layers of wall:

Perimetrium (outer)

Myometrium (middle)

Endometrium (inner)

Portions:

Body

Fundus

Isthmus

Location:

Anterior to rectum

Posterosuperior to bladder

Cervix

Location:

Below the isthmus of the uterus

Considered the narrow neck of the uterus

Projects into the vagina

Function:

Keeps uterus closed and fetus within it during pregnancy (collagen)

Vagina

Location:

Inferior to the uterus

Anterior to the rectum

Posterior to the urethra and bladder

Birth canal

3 layers:

Adventitia

Muscularis

Mucosa

Rugae


Vaginal orifice

Hymen

Extension of mucosa

Incomplete wall / diaphragm

Female External Genitalia = “Vulva”

Mons pubis

Rounded pad over the pubic symphysis

Labia

Major

Fatty skin folds with hair

Minor

Smaller, hairless folds inside major

3 parts:

Vestibule

created by labia minor

opening for urethra and vagina

Central tendon

Fourchette

Junction of labia minor

Female External Genitalia = “Vulva”

Clitoris

Superior to vestibule

Composed of erectile tissue

Homologous to the penis

Components:

Crura

Prepuce

Corpus cavernosa

No corpus spongiosum

Bulbs of vestibule

Engorge with blood to help grip the penis

Greater vestibular glands

Either side of vaginal opening

Secrete mucus to make intercourse possible

Vasculature and Innervation

Vasculature

Uterine arteries from internal iliac and arcuate branches = uterus

Ovarian arteries from abdominal aorta and ovarian branches of uterine arteries = ovaries

Innervation

Branches of Pudendal nerve (hypogastric plexus & pelvic splanchnic nerves)

Fertilization: sperm meets egg

Path of sperm:

Seminiferous tubules àtubulus rectus àrete testis àefferent ductules à duct of epididymis à vas deferens à ejaculatory duct à urethra àfemale’s vagina à uterus àoviduct

Path of egg:

ovary àperitoneal cavity àinfundibulum (oviduct) àoviduct

The meeting:

Sperm + egg meet in uterine tube àsperm penetrates egg = fertilization

Zygote à uterus for implantation in uterine wall

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 Pelvis and Contents