Reproductive Physiology Quiz 2

Cryptorchidism

Undescended testis, has a genetic component

When do testes descend for species

At different times across species

4 anatomy components of the testes

Testicular capsule, parenchyma, mediastinum, rete tubules

Testicular capsule

Dynamic suborgan covering the testes

Parenchyma

Functional tissue of the testes

Parenchyma % of cellular mass

60-70%

Mediastinum

Central connective tissue housing rete tubules

Rete tubules

Channels through which spermatozoa are transported out of the testes

2 functions of the testes

Produce spermatozoa (thermosensitive), synthesis of testosterone

4 functions of testosterone

Stimulates secondary sex characteristics, increases muscle development, promote accessory sex gland development (seminal fluid), maintains libido and reproductive tract form/function

Two layers of the testicular capsule

Visceral vaginal tunic, tunica albuginea

Histology of tunica albuginea

Highly vascularized

Histology of testicular muscularis

Contains smooth muscle fibers important to contract the testicular capsule and help spermatozoa movement into the rete tubules

2 functions of testicular capsule

Form the outer boundary of the testes and help spermatozoa movement into the rete tubules

2 anatomy components of the parenchyma

Tubular compartment containing seminiferous tubules and interstitial compartment containing leydig cells

What 4 components make up the interstitial compartment

Interstitial cell of leydig produces testosterone, capillaries, lymphatic vessles, and connective tissue to provide testes structure

Rete tubules function

Collect sperm from seminiferous tubules to take to the epididymis

Mediastinum function

Connects rete tubules to efferent ducts

3 anatomy components of the excurrent duct system

Efferent ducts, epididymal duct, and ductus deferens

Efferent ducts function

Move sperm and fluid from rete tubules to epididymis

Ductus deferens function

Transport sperm from epididymis to culatory ductus

Function of excurrent duct system

Final maturation, storage, and delivery of spermatozoa to the pelvic urethra

Anatomy of the epididymis

Single convoluted duct surrounded by smooth muscle

Three regions of the epididymis

Head, body, and tail

Epididymis head function

Proximal end absorbs fluid from rete testes while distal area secretes fluid

Epididymis body function

Sperm maturation takes place

Epididymis tail function

Storage of fully motile and fertile sperm that have undergone capacitation and therefore are able to bind oocytes

Epididymis function

Provides the environment for final maturation of spermatozoa conferring them with motility and potential fertility

Is sperm transport time in the epididymis affected by sexual stimulation

No

How do sperm mature as they move through the epididymis

Gradual maturation as sperm moves from the head to the tail while secretions infer biochemical changes to sperm

What percent of total epididymal sperm are located in the tail

70%

What does prolonged lack of sexual stimulation lead to

Increased stale sperm and decreased fertility when ejaculated

What does the concentration of stored spermatozoa depend on

Ejaculation frequency

What four anatomy components contribute to testicular thermoregulation

Scrotum, pampiniform plexus, cremaster muscle, dartos muscle

What does the pampiniform plexus do

Veins bringing blood back to the body from the testes absorb heat from the vein with warmer blood coming from the body to the testes.

Tunica dartos muscle function

Makes sure hot body temperature isn’t getting to the testes

Ductus deferens function

Transports sperm via muscle contractions from the tail to the ampulla

3 anatomy parts of the penis

Base, shaft, glans penis

What happens when there is more blood flow to the penis when aroused

The penis is less retracted

Retractor penis function

Retracts to allow for erection

Fibroelastic penis

Limited erectile tissue, utilizes sigmoid flexure (ram, bull, boar)

Glans penis

Stimulation is main trigger of ejaculation, heavily populated with sensory nerves

4 muscles involved with erection and ejaculation

Urethralis, retractor penis, ischiocavernosus muscle, bulbospongiousus muscle

Urethralis muscle function

Brings semen to the penile urethra

Retractor penis muscle function

Relaxes to allow for erection

Ischiocavernosus muscle function

Holds blood inside penis by contracting the crus penis

Bulbospongiousus muscle function

Contracts to empty extra-pelvic urethra during ejaculation

Accessory glands

Glands along the male reproductive tract that secrete fluid into the lumen of the pelvic urethra

3 male accessory glands

Seminal vesicles (vesicular glands) prostate, cowper’s (bulbourethral) glands

Vesicular glands (seminal vesicles)

Secrete fluid directly into pelvic urethra, ejaculate volume in bull and boar, plug in stallion

Prostate

Present in all species, cleans and lubricated urethra and adjusts to a neutral pH

Bulbourethral (cowpers) gland

Secrete alkaline fluid similarly to prostate

5 functions of seminal plasma

Transport (adds fluid volume and facilitates sperm movement), nourish, stimulates sperm motility (increases metabolic activity), retards sperm capacitation by coating with proteins, stimulates sperm transport in females

Chemical composition of seminal plasma

Energy source (fatty acids, amino acids), buffers, amino acids (protect sperm membranes), glycoproteins

What is accessory gland development dependent on

Testosterone

What triggers testosterone secretion

LH produced by Leydig cells

What makes up the adluminal compartment

Seminiferous tubules, sertoli cells

What makes up the basal compartment

Basement membrane and tight junctions

What makes up the interstitial compartment

In between space around leydig cellsW

What hormone is essential for spermatogenesis

Increased testosterone in seminiferous tubules from pulsatile LH

What happens if there is chronic and high LH

Leydig cells become refractory and stop producing testosterone

Spermatogenesis function

Continual gamete supply via stem cell renewal, recombination, maximize reproduction, immunologically privileged site

Where does spermatogenesis occur

Seminiferous tubules

3 phases of spermatogenesis

Proliferation, meiotic, differentiation

Proliferation phase

Spermatatogonial stem cells start diving mitotically (2n) and differentiate into spermatogonia

Meiotic phase

Meiosis 1 (secondary spermatocytes, 2n) and meiosis 2 (spermatids, n) completed

Differentiation phase

Spermatids become spermatozoa by undergoing intracellular rearrangement and released into lumen of seminiferous tubule, no further cell divisions

Where does the meiotic phase take place

Adluminal compartment

4 phases of the differentiation phase

Golgi phase, cap phase, acrosomal phase, maturation phase

Acrosome

Contains enzymes that digest a path through the jelly coat of the oocyte

Mitochondria function sperm

Provide energy in the form of ATP for the tail

Centrosome

Needed for 1st zygotic division

What does a nucleus of a sperm include

23 chromosomes, DNA tightly wound around protamines

Golgi phase

Initial acrosome formation, tail development, translocation of centrioles

Proximal centriole

Attachment point of tail (flagellum)

Distal centriole

Central portion of tail (tail fibers)

Cap phase (4 steps)

Acrosomal vesicle flattens and caps the nucleus, primitive tail grows from distal centriole, acrosome membrane formed, production of hydrolytic enzymes

Acrosome reaction

Exocytosis during fertilization, digest zona pellucida

Acrosomal phase

Acrosome covers 2/3 of nucleus, nucleus elongates, neck and annulus formation

Annulus

Junction between midpiece and principal piece

What do manchette microtubules become

Postnuclear cap

Maturation phase

Final sperm assembly, mitochondria surround midpiece, tail completed, released from seertoli cells

Spermiation

Release of sperm from sertoli cells

What is the maturation phase dependent on

FSH

What protects DNA while inside sperm

Chromatin keratinized with increased disulfide cross linking

Principal piece fiber arrangement

2 central fibrils through all tail pieces, 9 double fibrils through mid and principal pieces, 9 course outer fibers in the mid piece only

Laminated columns purpose

Gives neck flexibility so tail can move laterally when mobile

Total sperm count calculation

Total sperm= sperm concentration (per mL) x total volume (mL)

Ejaculate volum:8 mL

Concentration:1.2×10^9/mL

Progressive motility:70%

Normal morphology:92%

How many straws can be produced? How much semen extender is required?

412 straws, 198 mL

Primary sperm defects definition

Defects which occur during spermatogenesis

Secondary sperm defects definition

Defects which occur subsequent to spermiation