The Male Reproductive System

Question 1

intro

Answer 1

• specialised germ cells/gametes are used for procreating
• male germ cells: spermatoza
• female germ cells: ova

They fuse together to form a single zygote

the zygote goes through numerous cell division processes to form the embryo

remember the reproductive system shares the urinary tract and so can be called the urogenital tract

Question 2

Testis

Answer 2

3 key functions

• produce spermatozoa by

-produce fluid to transport the sperm from testes into the female

• secrete testosterone

Question 3

Testis development

Answer 3

• testes are not external until weeks - months after birth
• sometimes the testes can remain retained
• Cryptorchid - one testis retained
  -Bilateral cryptorchid - both testes retained

Question 4

Testis

Answer 4

• inside scrotum outside body cavity
• in order for spermatogenesis to happen- testicles require a cooler temp

Dartos muscle - helps control testicular temp
- thickens and contracts sctrotal skin in cold weather

• relaxes and becomes thinner in hotter weather

Question 5

Testicular tissue

Answer 5

consists of seminiferous tubules and lines with 2 types of cells

• spermatogenic cells - divide by meiosis to produce immature sperm or spermatids and these contain the haploid number of chromosomes

Sertoli cells - these secrete oestrogen and nutrients to prolong the survival of sperm

Question 6

Seminiferous tubules

Answer 6

between these are cells called leydig cells or intestitial cells

• secrete testosterone under control of the a hormone secreted by the anterior pituitary glands
• these train into the larger efferent ducts that drain into the epididymis

Question 7

Epididymis

Answer 7

• lies dorsal to the testis
• Cauda epididymis or tail is attached to the caudal extremity of the testes and the point at which the temp of the testis is the lowest
• storage and maturation of spermatozoa

Question 7

Testis blood Supply

Answer 7

-Blood supply to the testes is via the testicular artery

• this artery leaves the aorta in the abdomen caudal to the renal artery

testicular artery enters scrotum, runs down side of the epididymis and divides to form the pampiniform plexus (a capillary network)

Question 8

Vas Deferens

Answer 8

• deferent duct / spermatic duct
• thick smooth muscle walls
• connects with urethra
• during ejaculation the sperm and fluid produced in the seminiferous tubules are propelled along the epididymis and up the deferent duct to join the urethra
• the prostate gland surrounds the point where the deferent duct joins the urethra

Question 9

Penis

Answer 9

Coneys sperm and fluid from the testis into the female

convey urine from the bladder to the external environment

Question 10

penis

Answer 10

• composed of muscle, erectile tissue and connective tissue
• Large blood supply and many sensory nerve endings
• Contains a bone called the os penis/ baculum

Question 11

Penis : Dog

Answer 11

Bulb of the penis (bulbus glandis) - enlargement toward rear of the penis

• Engorges with blood; reaches full size after ejaculation
• remains clamped in place by contractions of the cingulum muscles in the vagina
• erection of the bulb subsides in 15-20 minutes

Question 12

Penis Cat:

Answer 12

• shorter and points backwards
  -barbed
• queens are induced ovulators
• barbs thought to induce ovulation at the end of mating
• Os penis lies ventral to the urethra

Question 13

Boar penis

Answer 13

-corkscrew
- matches cervix in sow

mimicked in artificial insemination

Question 14

Urethra

Answer 14

pelvic portion - entry point of vas deferens and accessory reproductive glands

• Penile portion - runs down the length of the penis
• Spermatozoa from vas deferens and secretions from accessory reproductive glands enter urethra and are pumped out as semen
• Also carries urine from the urinary bladder outside the body
• Urine flow temporarily blocked when ejaculation occurs

Question 15

Accessory Glands

Answer 15

Prostate and Bulbourethral glands

these are not present in dogs

function - secrete seminal fluid

seminial fluid increases the volume of ejaculate to aid passage of sperm

provide the correct environment for sperm survival

Neutralise the acidity of the urine found within the urethra

Question 16

benign prostatic hyperplasia/hypertrophy

Answer 16

this is a common problem in older entire male dogs. prostate becomes enlarged as dogs age.

Question 17

spermatogenesis

Answer 17

production of male sex cells

the hormone testosterone is produced in the interstitual spaces by the Leydig cells

stimulates production of sperm in seminiferous tubules of the testes

secretions from the sertoli cells in the seminiferous tubules nourish the sperm

When the spermatozoa are fully developed, they detach and are carried to the epididymis for storage before ejaculation

Question 18

Spermatozoon

Answer 18

Head - contains nucleus of the cell

Mid - piece - large concentration of mitochondria

Tail - contains muscle - like contractile fibrils