The Male Reproductive System Flashcards
intro
- 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
Testis
3 key functions
- produce spermatozoa by
-produce fluid to transport the sperm from testes into the female
- secrete testosterone
Testis development
- testes are not external until weeks - months after birth
- sometimes the testes can remain retained
- Cryptorchid - one testis retained
-Bilateral cryptorchid - both testes retained
Testis
- 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
Testicular tissue
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
Seminiferous tubules
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
Epididymis
- 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
Testis blood Supply
-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)
Vas Deferens
- 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
Penis
Coneys sperm and fluid from the testis into the female
convey urine from the bladder to the external environment
penis
- composed of muscle, erectile tissue and connective tissue
- Large blood supply and many sensory nerve endings
- Contains a bone called the os penis/ baculum
Penis : Dog
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
Penis Cat:
- 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
Boar penis
-corkscrew
- matches cervix in sow
mimicked in artificial insemination
Urethra
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
Accessory Glands
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
benign prostatic hyperplasia/hypertrophy
this is a common problem in older entire male dogs. prostate becomes enlarged as dogs age.
spermatogenesis
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
Spermatozoon
Head - contains nucleus of the cell
Mid - piece - large concentration of mitochondria
Tail - contains muscle - like contractile fibrils
