A. Testis

B. Epididymis

C. Scrotum

D. Spermatic Cord

E. Accessory Sex Glands

F. Urethra

G. Penis

H. Testicular Thermoregulation

Purpose of this system is to produce sperm and deliver the sperm to the female so fertilization can occur.

Function of the testis

1. Endocrine organ – produces hormones, lots of testosterone, inhibin, estradiol

2. Exocrine organ – produces sperm In land mammals - testes are suspended in a scrotum outside the body cavity (adult male). -Body communicates to testis through the inguinal canal with

– similar to an orange Seminiferous tubules are the flesh of the orange flesh separated into sections connective tissue layers skin of orange

– scrotum membrane - tunica albuginea segments

– septa (tunica vasculosa) central core - mediastinum

Parenchyma – seminiferous tubules, functional

Stroma – connective tissue layers

 – outermost portion of the testis, fibromuscular, smooth muscle elements and contractile, supports the tubules, applies pressure

-Projections from the tunica albuginea (septa) radiate into the parenchyma of the testis to the mediastinum to form lobules of seminiferous tubules.

 – site of spermatogenesis, sperm producing epithelium called germinal epithelium, tubule contortus 

-Interstitial space contains blood vessels (capillaries), lymphatics, macrophage, Interstitial cells of Leydig (Leydig cells).

L.C. – close to blood vessels, produce testosterone in response to hormone LH

Remove a tubule and cut it as a cross-section

Seminiferous tubule

1. Outer cell – peritubular myoid cells – modified smooth muscle cells, help keep the tubule together

2. basement membrane “myoid layer”

. Sertoli cells

4. differentiating germ cells

5. lumen

- wall of tubule which has germ cell producing region 4-5 cell layers thick including germ cells (developing sperm cells) in various steps of development

-The most undifferentiated or undeveloped cells are at the base of the epithelium and most developed at the lumen or apical surface. Sertoli (sustentacular) cells – support germ cell physically and with nutrients

-There are no capillaries in s. tubules – avascular

-Sperm proteins can cause an immune response to be generated by the male if these proteins leak out and enter the bloodstream.

-These proteins (sperm) are recognized as foreign.

-Antibodies form from sperm (or proteins)

immune response destroy the foreign cells - cell mediated response.

-Autoimmune infertility can result where male destroys his own sperm producing epithelium

1.Capillary wall – not very exclusive, leaky

2. peritubular myoid cell layer – some exclusion between adjacent cells

3. basement membrane – not much exclusion, immune cells can penetrate

4.Sertoli cells – most exclusive integral/important component of BTB, tight junctions (occluding junctions) form very selective permeability seal. For material to get into the adluminal compartment of the tubule, the material has to pass through the

Sertoli cell Keeps out: immune and other cells, toxins

1.basal compartment – differentiating germ cells undergoing mitosis

2. adluminal compartment – differentiating germ cells undergoing meiosis and differentiation

a. peripheral adluminal compartment

b. deep adluminal compartment

-The fluid composition of these two compartments is different and reflects the exclusive properties of the tight junctions.

– (ductus efferentes) small series of tubules connect rete testis and epididymal duct located at a dorsal pole of testes Epithelium – pseudostratified columnar epithelium principle columnar and basal cells

Muscularis of efferent duct is unique – only thin circular smooth muscle layer Lumen is collapsed with an uneven surface Efferent duct is responsive to estrogen (Estrogen knockout is infertile)

-Convoluted tubule lying in close opposition to the testes. -Comprised of epididymal duct and connective tissue support to form entire epididymis runs dorsal to lateral in reference to testis -Caput (head)

-Corpus (body)

-Cauda (tail)

Epithelium - pseudostratified columnar epithelium with basal cells and principal columnar cells with stereocillia (not really cilia - longer than more typical cilia found on epithelium, microvilli) increase surface area

-Also supporting the epithelium is a prominent layer of smooth muscle that is circular

-Lumen of the epididymal duct tends to be open and even

Functions of the epididymis

1.sperm transport –peristaltic like contractions (stereocillia)

2.concentration – fluid absorption (Sertoli and rete testis derived fluid) in the caput, sperm concentration increases

3.secretion – various segments of the epididymis contribute materials (proteins, etc) to the fluid

4.storage – cauda functions as the major storage regions, sperm can remain viable in the cauda for up to 60 days

5. maturation – sperm are not competent for motility or fertility until they transit through the epididymis, sperm are completely formed morphologically but they are not mature

– outer protective covering of testes

Four layers – skin, tunica dartos, fascia, parietal vaginal tunic

skin 

– hair covers the skin and skin is infiltrated with sweat and sebaceous glands, comprised of three layers, epidermis, dermis, hypodermis, lacks subcutaneous fat

 – smooth muscle running through the entire scrotum/continuous with skin gives rise to the scrotal septum (septum scroti) that forms two separate cavities in the scrotum (one testis in each).

-gives rise to the scrotal septum (septum scroti) that forms two separate cavities in the scrotum (one testis in each).

-Contraction causes testes to be brought close to body wall whereas relaxation causes testes to drop away.

Functions of the scrotum

1. Mechanical protection

2. thermoregulation – functions to regulate testicular temperature by proximity to body cavity, also hair and sweat glands participate in thermoregulation If the testes are maintained at core body temperature then the mammalian male is infertile.

 – condition in which testes have remained in the body cavity and have not descended into the scrotum

Bilateral cryptorchid – both testes are abdominal, this animal would be infertile

Unilateral cryptorchid – one testis is descended, animal could be fertile

Animal will display secondary sex characteristics because testes still produce testosterone

There is space between the visceral and parietal vaginal tunics; cavity of the tunica vaginalis

1. Ductus deferens

2. Artery and veins – pampiniform plexus

3. Lymphatic ducts and nerves

4. Cremaster muscle

5. Visceral and parietal vaginal tunic

Accessory Sex Glands

-Void secretions into the urethra, secretions make up the bulk of semen (seminal plasma), provide a vehicle for sperm transport and provide nutrients for sperm

-Androgens (testosterone) are important for growth and maintenance of all accessory sex glands.

-Generally, smooth muscle in walls that compresses gland and move fluid into urethra. (Exception is bulbourethral gland that also has skeletal muscle associated with it.)

– organic fluid, secretions of testis, epididymis, accessory sex glands complex solution with cells, sugars, amino acids, etc

– paired, grapelike appearing gland, multiple lobes, produces most of the seminal plasma in most species. Paired on either side of the urethra.

-Secretions consist of proteins, sugars, prostaglandins.

-Major source of fructose.

-Large in bull, boar and stallion

-absent in dog and cat.

 – most responsive to androgens, large in dogs and humans Cancer of prostate in humans and dogs. Benign hypertrophy - constrict the urethra.

The prostate is a fibromuscular exocrine gland

•complex proteolytic solution

•proteolytic enzymes liquefy the semen after ejaculation

•modify the vaginal environment to enhance sperm survival

•many of the components not determined

Two types

a. lobulated/discrete/corpus – body of the gland can be easily dissected out as a pair of lobes, situated on top of the pelvic urethra cat, dog, stallion, human

b. desseminate – gland is scattered throughout the pelvic urethralis muscle, imbedded in this muscle, small ducts lead from the glands into the urethral ram

c. mixed – both corpus and dessminate combined, boar, bull

Paired gland, very large in the boar surrounded by skeletal muscle called the bulbospongiosus (bulboglandularis) muscle. ----Secretions are thick – mucus and mucopolysaccharides.

-Vesicular glands proteins combine with mucus in the bulbourethral gland secretion forms the gel fraction in the boar ---Serves as the cervical plug in female

 – thickened, glandular region of the ductus deferens some secretions & some storage

-Present in boar, bull, ram, dog, stallion, with varying degrees of size and differentiation, absent in cat

(rodents) secretion forms vaginal plug (hard mucus deposit) vesiculase (enzyme) produces a plug

-Lies along the vesicular gland in mice, same embryonic origin as vesicular gland and prostate gland

– portion of the urethra extending through the penis

loss of muscle/skeletal muscle found in pelvic urethra so this is basically a tube in the penis

 – transport urine and semen

Emission - transport of sperm between the epididymis and the pelvic urethra

Ejaculation – transport of sperm/semen through the pelvic and penile urethra

Colliculus seminalis – site of the pelvic urethra where the ductus deferens/ampulla joins with pelvic urethra

Penis (plural penes)

There two types of penes:

Vascular (musculocavernous) – stallion, dogs, cats, human Fibroelastic – ruminants, boar

Major difference between the two types: proportion of vascular to fibroelastic tissue

 – dorsal, length of the penis arises from the ischial arch as a pair of cavernous canals called the crura (anatomic nomenclature for a leglike part)

Crura

 - attached to the descending portions of the pubic bone (singular = crus) The ischial arch is where the pelvic-penile urethra junction is located

– the vascular/spongy tissue surrounding the penile urethra, arises as a bulb of vascular tissue - the penile bulb

Penile bulb – surrounded by the paired skeletal muscle called the bulbospongiosus muscle

Erection canals

 – specialized structures in fibroelastic facilitates blood movement during erection to distal portions of the penis (CCP)

 – paired tubular shaped smooth muscle, arises from the vertebral column in the vicinity of the first coccygeal or last sacral vertebrae and attaches to the underside of the penis. 

 – S shaped bend in penis, associated with fibroelastic species

-Important in the fibroelastic species and functions to maintain the sigmoid flexure in its S shape. Important in erection and protrusion from the prepuce.

: CCP are large, during erection, size of the penis increases due to blood engorgement of the CCP

 – sheath of skin that the penis retracts from and into

Two parts :

pre-penile prepuce cranial of the penis Penile prepuce – immediately surrounding penis

Preputial pouch – boar, diverticulum of the prepenile prepuce that collects urine, epithelia cells, semen; gives the boar a particularly strong odor

Pampiniform plexus

-In the pampiniform plexus, the spermatic artery is intertwined with the spermatic vein, highly convoluted network.

-Blood is cooler leaving the testis from the testicular veins, the cooler venous blood cools the warm arterial blood before the arterial blood enters the testes.

-The net effect of importance is the cooling of the warm arterial blood before it enters the testes to keep testicular temperatures at 33-34 C.