Chapter 28 - A&P

Reproductive System

Vesicouterine pouch

Space between urinary bladder and uterus

Rectouterine pouch

Space between rectum and uterus

Ovary

Paired oval organs lateral to uterus, anchored by CT

• Has 2 layers

Ovarian artery / vein

Branch off of abdominal aorta

Mesovarium

Double fold of peritoneum that attaches to each ovary at hilum

Hilum

Blood vessels / nerves (autonomic) enter here

Mesovarium

Broad ligament

Drape of peritoneum hanging over uterus

Ovarian ligament

Sticks ovary to side of uterus

Suspensory ligament

Superficial anchor, surround ovarian artery/vein

Germinal epithelium

Outer layer of ovary

• Simple cuboidal epithelial layer surrounding ovary

Tunica albuginea

Inner layer of ovary

• Connective tissue capsule

Cortex

Outside

• Contains ovarian follicles

Medulla

Inside (ovaries)

• Contains branches of ovarian blood
  vessels, lymph vessels, nerves

Ovarian follicle

Consist of oocyte (egg) surrounded by follicle cells for support

• Thousands found in cortex

• 6 main types of ovarian follicle representing different stages of development

• Primordial follicle → primary follicle → secondary follicle → vesicular follicle → corpus luteum → corpus albicans

Oocyte

Egg produced in the ovaries

Follicle cell (granulosa)

Cells surrounding an oocyte (egg) that provide support

Primordial follicle

• Most primitive type of ovarian follicle

• Primary oocyte and single flattened layer of follicle cells

  • Primary oocyte arrested in
    meiotic prophase

• 1.5 million present at birth

Primary oocyte

Arrested in meiotic prophase, immature female germ cell that undergoes meiosis to become an egg

Primary follicle

• Primary oocyte + follicle cells which
  matured → aka granlulosa cells

• Follicle secretes estrogen

• Thecal cells on periphery of follicle

  • Help control follicle development

  • Secrete androgens (precursor to estrogen)

Granlulosa cells

Primary oocyte + follicle cells which matured → __________ _____

• Support and nourish oocytes, forming the follicle

Estrogen

• Secreted by follicle

• One of the sex hormones

• Assists development of mature ovarian follicle

Thecal cell

On periphery of follicle

• Help control follicle development

• Secrete androgens (precursor to estrogen)

Androgen

Secreted by Thecal cells

• Precursor to estrogen

Secondary follicle

Primary oocyte, thecal cells, granulosa cells, fluid-filled space,
antrum

• In the antrum, serous fluid increases as ovulation nears

• Oocyte forced to one side of follicle

Antrum

Fluid-filled space

• Serous fluid increases here as ovulation nears

Vesicular follicle

• Contains a secondary oocyte

  • Primary follicle divides from
    46 chromosomes to 23 chromosomes in meiosis

  • One formed per month

Secondary oocyte

• Primary follicle divides from
  46 chromosomes to 23
  chromosomes in meiosis

• One formed per month

Corpus luteum

• After mature follicle ruptures (ovulation) and oocyte expelled

  • Remnants is left in ovary

• Secretes sex hormones progesterone
  and estrogen

  • = buildup of uterine lining

  • Prepare uterus for possible
    implantation of fertilized oocyte

Ovulation

• Release of secondary oocyte from
  mature follicle, one ovary

• Occurs on day 14 of 28-day cycle

• Increased LH causes antrum expands until ovarian surface thins

  • Eventually ruptures, expelling
    secondary oocyte

After mature follicle ruptures…

Progesterone

Secreted from corpus luteum

Corpus albicans

Formed from regression of corpus luteum, scar tissue

Oogenesis

• Maturation of a primary oocyte → secondary oocyte

• Occurs in stages over the life of a female

Oogonia

Ovary contains primordial germ cells called…

• 1.5 million follicles within ovarian
  cortex at birth

• During puberty they divide by mitosis
  into primary oocytes

Atresia

Regression of some primordial follicles in childhood

Ovarian cycle

From puberty to menopause
◦ Hypothalamus release of gonadotropin-releasing hormone (GnRH)
◦ This stimulates release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

• Levels vary in cyclical pattern

• Produce monthly sequence of events

• 3 phases
  ˗ 1. Follicular
  ˗ 2. Ovulation
  ˗ 3. Luteal

Follicular phase

• Days 1–13 of 28-day ovarian cycle

• ~20 primordial follicles are stimulated to mature by FSH and LH

• Follicular cells

  • Release hormone, inhibin which blocks FSH production

  • Prevents excessive follicle development

• Few primary follicles maturing → secondary follicles

  • Usually only one matures → vesicular follicle

• Volume of fluid increases within follicle antrum

• Oocyte forced to one side of follicle

Continued

Primary oocyte in vesicular follicle
◦ Diploid – 46 chromosomes
o Finishes meiosis I and forms two cells (haploid)
◦ One polar body
o Nonfunctional, regresses
◦ One secondary oocyte
o Receives bulk of cytoplasm
o Completes meiosis if fertilized – ovum (diploid)
o Added ½ genetic information from sperm

Inhibin

Follicular cells release this…

• Blocks FSH production

• Prevents excess follicle development

Polar body

Nonfunctional, regresses

Diploid

46 chromosomes

• Finishes meiosis I and forms two cells (haploid)

Haploid

Finishes meiosis I and forms two cells

• 46 → containing 23 chromosomes each

Ovum

Completes meiosis if fertilized – ____ (diploid)

• Added ½ genetic information from sperm

Ovulation

• Release of secondary oocyte from mature follicle, one ovary

• Occurs on day 14 of 28-day cycle

• Increased LH causes antrum expands until ovarian surface thins

  • Eventually ruptures, expelling secondary oocyte

Luteal phase

◦ Remaining follicle cells become corpus luteum
◦ Days 15—28 of cycle
◦ Corpus luteum

• Temporary endocrine gland

• Secretes progesterone and estrogen to build lining for fertilized oocyte

• Life span of 10 to 13 days if oocyte not fertilized

◦ Corpus luteum regression

• Causes drop in secreted progesterone and
  estrogen

• Causes shedding of uterine lining –
  menstruation

Menstruation

Shedding of uterine lining

Menopause

Women cease cycling for 1 year
◦ Age 45 to 55
◦ No more ovarian follicles remain or follicle maturation stops, uterine lining no longer growing, decrease in progesterone and estrogen production

Hypothalamus

Secretes GnRH

• Stimulates anterior pituitary to secrete FSH and LH

GnRH

Stimulates anterior pituitary to secrete FSH and LH

Negative feedback

Maturing ovarian follicles secrete inhibin and estrogen
o Negative feedback effect on hypothalamus and anterior pituitary (ovarian cycle)

Positive feedback

• Estrogen assists development of mature ovarian follicle

• Mature follicle produces a larger amount of estrogen
  o Positive feedback loop initiated

• Feedback loop results in an LH surge from anterior pituitary

Uterus

• Muscular organ

• Implantation site for pre-embryo

• Supports, protects, nourishes developing embryo
  o Forms vascular connection that develops into placenta

• Ejects fetus at birth

• Contracts and sheds lining if oocyte not fertilized

Uterine tubes (Fallopian tubes)

◦ Extend laterally from both sides of uterus toward ovaries
◦ Transport ovulated oocyte → uterus
o Wall: Mucosa, muscularis, serosa
o Mucosa has cilia on cells to draw oocyte into uterin

Infundibulum

o Free, funnel-shaped, lateral margin of uterine tube
o Numerous fingerlike folds, fimbriae

Ampulla

o Expanded region of tube medial to infundibulum
o Fertilization happens here

(Uterine tube region)

Isthmus

Region of uterine tube extending from ampulla

Uterine part of tube

• Extends medially from isthmus

• Penetrates wall of uterus

Uterus— Main structures

• Muscles of pelvic floor

• Round ligaments (CT fibromuscular band supporting the uterus in females)

• Transverse cervical ligaments (paired structures providing support to the female pelvic organs and help maintain position of the uterus)

• Uterosacral ligaments (thick bands of CT that help support your uterus. Travel from the base of uterus to lower spine.

Tunics of uterus

3 concentric tunis of uterine wall: perimetrium (outermost), myometrium (muscle), and endometrium (innermost, sheds each month if not fertilized)

Fundus of uterus

Top part of the uterus, above the entrance of the uterine tubes, dome shape

Body of uterus

Thick wall of smooth muscle

Isthmus of uterus

Narrow part of the uterus located between the body and cervix.

Cervix

Projects to vagina

Vagina

◦ Thick-walled, fibromuscular tube
◦ Thin, distensible wall with 3 tunics
o Mucosa, muscularis (lots of this), adventitia (elastic fibers)

Uterine cycle

◦ Cyclical changes in endometrial lining
◦ Influenced by estrogen and progesterone
◦ 3 phases: menstrual, proliferative, secretory

Menstrual phase

• Days 1-5 of cycle

• Sloughing off of the functional layer

• Lasts through period of menstrual bleeding

• During ovarian follicular phase

Proliferative phase

• Days 6-14 of cycle

• Development of new functional layer of endometrium

  • Overlaps time of follicle growth and ovary estrogen secretion

• During ovarian follicular phase and ovulation

Secretory phase

• Days 15-28 of cycle

• Increased progesterone secretion from corpus luteum

• Results in increased urine vascularization

• If fertilization does not occur

  • Degeneration of corpus luteum

  • Dramatic drop of progesterone

  • Without progesterone, sloughs off functional layer

• During ovarian luteal phase

Ovarian cycle and uterine cycle phases

◦ Menstrual phase during ovarian follicular phase
◦ Proliferative phase during ovarian follicular phase and ovulation
◦ Secretory phase during ovarian luteal phase

Clitoris

A small, sensitive organ located at the anterior part of the vulva, playing a key role in female sexual arousal and pleasure.

Labia

The folds of skin surrounding the vaginal opening, providing protection and sensitivity as part of the female external genitalia.

Prepuce

A fold of skin that covers the glans of the clitoris, often referred to as the clitoral hood, which protects the sensitive area.

Mammary gland

(breast)

◦ Each located within anterior thoracic wall
◦ Composed of tubuloalveolar apocrine gland
◦ Secretory product, breast milk
o Proteins, fats, lactose sugar for infant nutrition

Suspensory ligament (breast)

A connective tissue that supports the breast, helping to maintain its position and shape.

Lobe (breast)

A large division of the breast composed of glandular tissue that produces milk, typically containing several lobules.

• Individual section of breast tissue

Lactiferous sinus

Stores milk prior to release

Lactiferous ducts

Drain lobe of breast

Lobule of breast

A small division within a lobe of the breast that contains glandular tissue responsible for milk production.

Alveoli

Small sacs in the breast where milk is produced.

Areola

The pigmented skin area surrounding the nipple that contains small glands to help lubricate the nipple during breastfeeding.

Nipple

The projection on the surface of the breast through which milk is delivered during breastfeeding, surrounded by the areola.

Prolactin

Produced in anterior pituitary and responsible for milk production

Oxytocin

• Produced by hypothalams and release from posterior pituitary

• Responsible for milk ejection

Breast milk release (lactation)

Occurs in response to internal and external stimuli

Testes

• Relatively small organs housed within the scrotum

• Produce sperm and androgens

• Covered by a serous membrane

  • Outer parietal layer and inner visceral layer

    • Separated by cavity filled with serous fluid

• Tunica albuginea

Penis

Carries sperm into the female body and also lets urine exit the body.

◦ Root
o Internally attached portion of _____
◦ Body
o Elongated movable portion
◦ Glans
o Tip of ______
o Contains external urethral orifice
◦ Prepuce (foreskin)
o Circular fold of skin

Accessory reproductive organ

Scrotum

◦ Skin-covered sac between thighs
◦ Provides cooler environment
o Needed for sperm development and
maturation
o Raphe - Midline seam in scrotal sac
oTestis reside inside
o Sac has the ability to contract and relax
based on temperature to move the testes towards and away from the body
o Position controlled by the dartos and
cremaster muscles

Raphe

Midline seam in scrotal sac

Dartos

Smooth muscle layer in the scrotum that helps regulate temperature by contracting or relaxing.

Cremaster

Skeletal muscle that raises or lowers the testes to regulate temperature.

Tunica albuginea

• Thick fibrous capsule covering the testis

• Deep to visceral layer

Mediastinum testes

• Thickening of tunica albuginea projecting into interior testis

• Blood vessels, ducts, lymph vessels, nerves enter or leave through here (basically the hilum of the testis)

Septa

o Internal projections of tunica albuginea
o Subdivide internal space into 250 lobules

Lobule

A small compartment within the testis, formed by the septa of the tunica albuginea, housing seminiferous tubules where sperm production occurs.

Seminiferous tubule

o Extremely convoluted and elongated, up to 4 per lobule
o Sustentacular cells
o Contain dividing germ cells continuously producing sperm

Sustentacular cells

Non-dividing support cells
˗ Nourish developing sperm
˗ Release hormone inhibin when sperm count high
˗ Inhibits FSH secretion and regulates sperm production

Blood-testes barrier

Protects developing sperm from material in blood

Interstitial spaces

Spaces surrounding seminiferous tubules

Interstitial cells

o Reside in interstitial spaces
o Stimulated to produce androgens by luteinizing hormone
o Most common androgen, testosterone
o Majority released from these cells; small amounts secreted by adrenal cortex

Androgen binding protein

FSH stimulates sustentacular cells to secrete this…

• Binds to testosterone increasing level in testes

Libido

Testosterone stimulates ______

• Refers to an individual's overall sexual drive or desire for sexual activity, influenced by hormones such as testosterone.

Secondary sex characteristic

Testosterone stimulates the development of…

• Hair growth in axillary and pubic regions, deeper voice, facial hair