Reproduction Overview::

Organs --> primary sex organs --> gonads

 function to produce gametes and steroid hormones

Accessory organs --> ducts, glands, external genitalia

 function to protect and aid in delivery

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Male Reproductive System ::

Male gonad --> testes :: to produce sperm and androgens

Accessory Organs --> scrotum, ducts, glands, penis

fxn : to protect sperm and aid in delivery

  A. Scrotum/Testes

  Scrotum :

 body temperature this is possible by the function of two muscles

1. Smooth muscle called the dartos m.

2. Skeletal muscle extension of the Internal Oblique muscle

 Testes : surrounded by two tunics :

1. Tunica Vaginalis : outer tunic from the two peritoneal layers (parietal and visceral)

2. Tunica Albuginea : inner tunic formed from fibrous connective tissue that creates a capsule that will divide the testes into compartments or lobules. Each lobule contains 1-4 coiled Seminiferous tubules. Seminiferous Tubules function to produce sperm and will be tied together at the rete testis --> efferent ductules --> epididymus

Interstial Cells : between the seminiferous tubules produce androgens.... primarily testosterone

Testicular descent :: testes start in the abdominal cavity at the ventral pole of the kidneys and will be "pulled" by the gubernaculum through the inguinal canal into the scrotum

  Blood supply :: testicular artery from the abdominal aorta

   Testicular vein that will form a network around the testicular artery and is called the pampiniform plexus.  The function is to absorb heat from the testicular artery   to cool the testes.

The spermatic cord is a connective tissue sheath that will contain the blood supply to the testes as well as lymphatics and ANS nerves as they travel through the inginual canal.

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B. Duct System :: epididymus, ductus defrens, urethra

1. Epididymus....has head, body, and tail

duct of the epididymus histology :

fxn --> transport of sperm that takes 20 days, during which the sperm become motile and fertile.

Also storage of sperm in the tail region for several months. If sperm not used, they are phagocytized.

 

2. Ductus Deferens (Vas Deferens)... from the epididymis into the spermatic cord & over the

ureter --> will then expand to form the ampulla and then join the duct of the seminal vesicle to form the ejaculatory duct.

The ejaculatory duct will empty into the prostate and then will empty into the urethra.

Fxn : propel sperm from storage sites to the urethra smooth muscle in the wall that creates peristaltic waves.

 

3. Urethra .. function for urinary and reproduction

Three regions ::

II. Accessory Glands ::  Seminal Vesicles, Bulbourethral, Prostate

a. Seminal Vesicle :: paired gland, posterior to the bladder

         secretion is 60% of the total glandular secretion

         contains :: sugar source, Vitamin C, prostaglandins, coagulating enzyme

b. Bulbourethral :: inferior to the prostate

      secretion is 10% of the volume, is a thick mucus and will neutralize the acidic urine traces in the urethra.

c. Prostate :: encircles the upper part of the urethra, in an encapsulated single gland

secretion is 30% of the total volume and is an alkaline enzyme fluid that functions to activate the sperm as they enter the urethra.

           Contains several enzymes

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III. External Genitalia ::

Penis.. fxn to deliver sperm

  External anatomy ... root, shaft, glans with loose skin at the proximal end called the prepuce

  Internal Anatomy ... spongy urethra

                                     erectile tissue in three columns

Erectile tissue ::

1. corpus cavernosum in the dorsal area in two columns, will expand proximally to form the crura to anchor the penis to the pubic arch

2. corpus spongiosum around the urethra will expand proximally to form part of the root called the bulb of the penis and expands distally to form the glans penis

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IV. Semen :: mixture of sperm and accessory gland secretions

approx. 2-6 ml per ejaculate containing 50-100 million sperm per ml.

liquid that provides transport medium, nutrients, & chemical for activation

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V. Physiology :: spermatogenesis :: sperm formation in the seminiferous tubules

A. Meiosis :: two nuclear divisions that decrease the chromosome number in half, called the haploid number , 1n

Meiosis I and Meiosis II

1. Meiosis I -->

replication and crossover in prophase I, meet at equatorial plate in metaphase I

separate, sister chromatids remain together, two daughter cells that are 1n by end of telophaseI

   Meiosis I is a reduction division and allows for genetic variability due to crossing over

2. Meiosis II -->

same as meiosis I, but no replication in prophase chromosomes of daughter cells parceled out into four cells and this division is called the Equitational Division

Fxn of meiosis

Mitosis and Meiosi in Seminiferous Tubules ::

Spermatogenic cells --> at the walls of the tubules that will give rise to sperm

Spermatogonia :: outermost, least differentiated in direct contact with basal lamina these stem cells that will divide by mitosis to form

Primary spermatocyte --> meiosis I --> secondary spermatocyte --> meiosis II --> spermatids

Spermatids undergo spermiogenesis to become a sperm(atozoa)

 

Sperm ::

Sustentacular Cells ::

Supporting cells that surround the dividing spermatogonia

Extend from the basal lamina to the lumen and are in two regions ::

a. Basal Compartment :: from lamina to stem

b. Adluminal Compartment active cells at the lumen

tight junctions between the two compartments form the blood testes barrier to prevent sperm antigen from escaping through the basal lamina into the blood.
also provides protection from the immune system as sperm membrane are antigenic since the immune system is not immunocompetent to sperm.
Sperm in the blood would provoke an autoimmune response and cause sterility.

function ::

Process of spermatogenesis from the primary spermatocyte to release of immature sperm takes 64-72 days.

Sperm are moved by peristaltic waves through the tubular system of the testes to the epididymis where they undergo further maturation.

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VI. Male sexual response ::      

1. Erection of the penis

2. Ejaculation

\1. Erection :: erectile tissue of the penis becomes engorged due to parasympathetic reflex, from the sacral division

a. arterioles dilate

b. expansion compresses drainage of veins and decrease the blood outflow

cause --

failure to attain an erection --> impotence : can be temporary and reversible or irreversible

 

\2. Ejaculation :: propulsion of semen from male duct system

sympathetic nerves (L1 - L2)

* ducts/glands contract, peristaltic waves

* bladder sphincter constrict to prevent urine from entering into the urethra

* bulbospongiosus muscle contract to propel semen from the urethra

  Entire event called :: Climax or Orgasm

  Will be followed by ...

VII. Hormonal Regulation :

Brain-Testicular Axis

* spermatogenesis

* androgen production

  Hypothalamus --> GnRH  ==> AP --> FSH, LH ==> testes

FSH :: makes the testes more responsive to testosterone & allows for spermatogenesis

LH :: interstitial cells to secrete testosterone

1. Hypothalamus - AP  .... negative feedback inhibition

2. Inhibin by Sustentacular (sertoli) cells

3. Androgen Binding protein from the Sustentacular cells

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VII. Testosterone ::

Synthesized from cholesterol, activated genes to transcribe mRNA

* spermatogenesis

* accessory reproductive structures

* secondary sex characteristics ::

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Female Reproductive System ::

1. reproductive organs ... Ovaries

* gamete production....ova

* hormone production...

2. Accessory Ducts ... transport, support fetus

 

Ovaries and ducts are the internal genitalia

  External Sex organs are the external genitalia

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I. Ovaries ::

A. Ligaments will contain blood vessels, lymphatics, and nerves and provide support for the internal structures

* ovarian ligaments -- anchors ovary to uterus

* suspensory ligaments -- anchors ovary to the abdominal wall

* mesovarium, part of the broad ligament, and is between the ovary and uterine tube.

the broad ligament is a peritoneal fold and consists of

B. Blood Supply :: ovarian a. from abdominal aorta & the  ovarian br. of the uterine artery

C. Coverings :: tunica albuginea

D. Divisions :: cortex, medulla (small area), hilus where blood vessels, lymphatics, nerves enter

Cortex... ovarian follicles which have oocytes with various layers and will be at different stages.

  Ovulation :: mature follicle ejects oocyte

  Corpus Luteum :: ruptured follicle

  Corpus Albicans : degenerated Corpus Luteum (CL)

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II. Duct System -->

A. Uterine Tubes (Fallopian tubes, oviducts)

tubes supported by mesosalphinx (visceral peritoneum)

Fxn : receives oocyte and is the site of fertilization

Around the ovary, the tube expands to form the ampulla  and this will enlarge to form a funnel shaped region called the infundibulum that has fimbrae that will beat in wave like motion to capture the oocyte that is released at ovulation. At the uterine end, will constrict to form the isthmus

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III. Uterus

Function :: retain/nourish fertilized egg

Regions :: fundus, body, isthmus, cervix, cervical canal with internal & external os

  Histology of the Uterus

Perimetrium :: outermost, serosal layer, visceral peritoneum

Myometrium :: middle layer, smooth muscle

Endometrium :: inner layer, mucosal lining consisting of the lamina propria

  (basement membrane) and simple columnar epithelium in two layers

 

Blood Supply ::

Uterine Artery (branch of internal iliac) --> arcuate a.

(supplies myometrium) --> radial a. branch ( to the endometrium) and will form :

1. Straight A.  for supply to Stratum Basalis

2. Coiled (Spiral) A. for supply to Stratum functionalis.

      This artery will go into spasms, decrease the blood flow and O2 to this layer, causing it to die and eventually slough off during menses.

  Support :: ligaments

Ligament function :: provide support and allow some mobility and position change of the uterus

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IV. Vagina

A fibromuscular tube that extends from the cervix to the exterior.

Proximal region is folded near the cervix to form the vaginal fornix and loosely surrounds the cervix

Fxn :: menstrual flow, passageway for the infant (birth canal) organ of copulation

Histo....

V. External Genitalia ::  Collectively called the Vulva

All organs that lie external to the vagina :

1. Mons Pubis :: fatty area over the pubic symphysis

2. Labia Majora :: counter part to the scrotum

3. Labia Minor :: counter part to the ventral penis enclose the vestibule which has the openings ::

4. Clitoris :: erectile tissue --> corpora spongiosum (analogous to the glans penis)

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VI. Mammary Glands

Present in both sexes, normally functional only in females

Modified exocrine sweat glands that produce milk when active

External Anatomy of the Mammary Glands ::

Internal Anatomy of the Mammary Glands ::

15-25 lobes that are separated by connective tissue & fat

C.T. forms suspensory ligaments for breast attachment to the pectoral muscle fascia

Lobes consist of lobules that have glandular alveoli that function to produce milk

Alveolar glands --> lactiferous ducts --> lactiferous

       sinus --> opening of duct at nipple

Hormones ::

Milk production ::

In the nonpregnant female, the mammary glands are primarily ducts and adipose tissue

In the pregnant female, there is increased gland development.

Colostrum is the first "milk" produced, and milk production is under a positive feedback control.

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Female Reproductive Physiology ::

Oogenesis :: starts before birth and continues @ puberty

1. Fetal Development

Oogonia.... 2n stem cell will undergo Mitosis to produce primary oocyte

This oocyte will have a single layer of squamous follicle cells and be referred to as a Primordial Follicle
The primary oocyte will continue into Meiosis I and stop at prophase I after duplicating its chromosomes.
Some primordial follicles will degenerate, most in arrested state in the cortex of the ovary

2. At puberty, Meiosis I continues in one selected follicle.

From Meiosis I division there is a first polar body (1n) that has very little cytoplasm and
a secondary oocyte (1n) that gets most of the cytoplasm and all of the organelles

This secondary oocyte stops in metaphase II of meiosis II, and will be ovulated from the tertiary follicle.

 

3. The ovulated oocyte will degenerate if no sperm fuses with the membrane.

   If a sperm fuses with the membrane, the secondary oocyte will complete Meiosis II and divide into a secondary polar body and a functional gamete called the ovum

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Ovarian Cycle :: three phases that last 28 days (4 weeks)

1. Follicular phase.... maturation of the primordial follicle on the days 1-10

primordial follicle (primary oocyte w/ single layer) --> primary follicle (secondary ooctye w/ multi layers)

Primary follicle has 2+ layers of cuboidal follicle cells and will become a secondary follicle that has more cuboidal cells called the granulosa cells and a connective tissue cell layer called the thecal cells.  Both cells (granulosa and thecal) will secrete estrogen and the granulosa cells will also secrete a glycoprotein membrane around the secondary oocyte.
This membrane is called the Zona Pellucida

Secondary Follicles will become Tertiary Follicles (also known as Graafian) follicles as the antrum (chamber) expands. 
The granulosa cells will form the corona radiata around the secondary oocyte and maintain the connection by a stalk of cells

2. Ovulatory phase .... ovulation,  days 10-14

increases in fluid will free the secondary oocyte from the follicle
ovulation :: ovarian wall ruptures and releases the secondary oocyte with its corona radiata

 

3. Luteal Phase... corpus luteum activity,  days 14-28

Ruptured follicle collapses and fills with blood and is called a corpus hemorrhagicum

The remaining granulosa cells and internal thecal cells increase in size and form the C.L.

(Corpus Luteum ). The CL will secrete progesterone and some estrogen .

If no pregnancy... within 10 days the CL will degenerate and form a scar tissue called the corpus albicans.
If pregnancy... CL persists until the placenta takes over

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Ovarian Cycle :: Hormonal Regulation ...

GnRH from hypothalamus -->  FSH, LH from the Anterior Pituitary --> Ovaries

FSH.... affect the follicles and granulosa cells

LH... affect the Thecal Cells

Both will produce estrogens

With increases in estrogen, there is an LH surge from the AP  to causes the mature follicle to ovulate oocyte

Uterine Cycle :: Changes in uterine endometrium, in three phases::

1. Menses :: stratum functionalis destruction and shedding

   lasts 3-5 days

   spiral arteries constrict to decrease blood flow to decrease oxygen and tissue dies.

Arterial walls rupture and there is bleeding into the connective tissue of this layer. Degenerating tissue breaks away

 

2. Proliferative (pre-ovulatory):: stratum basalis replaces the stratum functionalis

uterine glands multiply and under the influence of increasing estrogen, there is growth and revascularization

This phase is occurring during the changes in the ovarian follicle from a primary to a secondary follicle.

3. Secretory (post-ovulatory):: begins at the time of ovulation

Increased progesterone from CL causes the

Estrogens :: a cholesterol derivative, functions to

Progesterone :: (Progestin)  a cholesterol derivative

Female Sexual Response ::

a. Erection.... engorgement with blood for the clitoris, vaginal mucosa and breasts

b. Orgasm... increased muscle tension and uterine contraction

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Problems ::

Infertility, Infection, Cancer (ovarian, uterine)

Sexually Transmitted diseases [STD] ::

1. Gonorrhea ... Neisseria bacterial

2. Syphilis ... Treponema, bacterial

3. Chlamydia .. bacterial, can infect infant when passing through birth canal

4. Genital Herpes .. viral

5. AIDS ... viral

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Aging Changes ::

1. Females --> Menopause, due to decreased estrogen levels  despite increased FSH, LH (decrease receptors)

2. Males --> decreased testosterone, decreased libido