topic 8: reproduction system Flashcards
how many chromosomes do dogs have
39 pairs
what is mitosis
A type of cell division that results in two daughter cells
each having the same number and kind of
chromosomes as the parent cell (creating clones)
what is meiosis
A type of cell division that results in
daughter cells each with half the
number of chromosomes of the
parent cell
* Sex cells (sperm and ovum) are
produced in this way
Ensures that the fertilized egg from
the union of sperm and ovum has
the same number of chromosomes
as parent cell (fuse tgt will have the same number of chromosomes as parent cell)
what is male dog and male cat known as
male dog: male
male cat: tomcat
what are the parts of the male reproductive tract
-testes
-duct system( Epididymis, vas deferen, urethra)
external genetalia: scrotum and penis
accessory glands: prostate gland (dog, cat, rat) bulbourethral gland (cats)
describe the location of the testes
located outside of abdomen ( vecuase normal internal body temp is too high for sperm developement)
describe the function of the testes
-sperm production
hormone production: testosterone (influeces developement of sperm and male secondary sexual characteristics)
describe the structure of the testes
testicular tissue is devided into numerous conical compartments each containing a coiled mass of seminiferous tubules (where sperm is produced) and interstitial cells (secrete the male hormone testonsterone) . the seminiferous tubes eventually join to form the epididymis
structure of epididymis
a highly convulated duct dorsal to testes. the tail of the epididdymis continues as the vas deferens: sperm travels from epididymis to von deferens.
function of epididymis
-sperms formed in the seminiferous tubules mature during the passage into the epididymis
-they are stored within the epididymis before propelling along the vas deferen during ejaculation
function of the vas deferen
carry sperm quickly from epididymis to urethra during ejaculation
function of scrotum
-skin pouch that houses the testes
- helps regulate temperature of testes
-maintains testes at 3 degress celcius lower than body temperature to protect sperm viability
explain how scrotus regulation temperature of testes
two muscles ( cremaster and dartos) attach the scrotum to pull the scrotum closer to the body when its colder and relax when its warm
describe the structure of the penis
-consists of urethra surrounder by layers of erectile tissues, muscle and connective tissues to enable its entry into the female vagina during coitus
-embeded within the erectile tiddue close to the tip is the os penis: its function os to aid in the entry of the penis into the female tract before ejjaculation is fully complete
-penis also has a rich blood supply and many sensory nerve endings
what is the function of the penis
-convey sperm and fluid from the tesis into the femal reporductive tract during mating
-convet urine from the bladder to ouside via the urethra
list the major accessory glanf in dogs and cat reproductive system and describe their function
function: sperm only makes up a vert small portion of the semen, majority of semen is made up of secretion of the various accessory glands
the accessory glands produce an alkaline fluid ( electrolytes, fructose, prostaglandins) whuch protect the sperm by counteracting the acidity of the female reproductive tract
prostate gland: dog and cat (all domestic animals)
bulbourethral gland: cat only
what is a female dog and cat known as
female dog: bitch
female cat: queen
what are the parts of the female reproductive system
-ovary
-oviduct
-uterus
-cervix
-vagina
-vulva
describe the structure and location of the ovaries
structure: within the ovarian collective tissues are many primary follicles, each that develops into a mature folicle. each mature follicle contains a small amount of fluid and an ovum
location: lies on each side of the dorsal part of the abdominal cavity, caudal to kidney
function of ovaries
-produce ova
-secrete hormones: estrogen. progesterone
structure of the oviduct
Small tubes extending from the tips of
the uterine horns
* Finger-like projections at the tip
known as fimbriae, which capture the
ovum released from ovaries
* Oviduct also provide a site for
fertilization
* Cilia inside the uterine tube slowly
move the fertilized ova towards the
uterus (takes 3–4 days)
function of oviduct
To collect ova as they are
released from the ovaries
* To convey the ova from the
ovaries to the uterine horns
* To provide the correct
environment for the survival of
both the ova and sperm for
fertilisation
strucuture of the uterus
- Y-shaped structure
- The Uterine body
forms the base of the Y - Uterine horns form the
arms
Walls of the uterus - Endometrium: inner mucosal layer
– secreting mucus and other substances
– allows for implantation of a fertilized egg - During pregnancy this layer thickens to provide
nutrition for the embryo before implantation and to
support the developing placenta - Myometrium: middle layers of smooth muscle
– produces strong contractions during parturition - Perimetrium: outer visceral layer of peritoneum
– suspends the uterus from the dorsal body wall
function of the uterus
Provide a site where the embryos can develop
into new animal
* Provide the means whereby the developing
embryos can receive nutrition from the mother
– via the placenta.
structure of cervix
A short, thick
-walled muscular
sphincter, which connects the
uterine body with the vagina
* The lumen of the cervix is known as
the cervical canal
* It is normally tightly closed, and
dilates only to allow the passage of
sperm, or foetus during parturition
* During pregnancy, the canal is
blocked by a mucous plug which
protects the embryos from infection
function of cervix?
strucutre of vagina and vulva
The Vagina is the tube that leads to the external
opening
The Vulva is external part of the female
reproductive system.
* Guarded by a pair of vertical labia.
* It is the labia that become visibly engorged with
blood when the bitch is in season.
* Lying between the labia is a knob of erectile
tissue known as the clitoris.
function of vagina and vulva
Receives the penis at breeding, and
* Serve as the birth canal at birth
Examples of uniparous species
One mature ovum per cycle
Horse, cow, human
Example of multiparous species
Multiple ova produced per cycle
Cat dog sow (female pig)
- Describe a complete ovarian cycle starting from a primary
follicle to corpus luteum regression
- Beginning with primary follicle: immature ovum
surrounded by a single layer of follicular cells (thousands of
primary follicle) - Once activated by follicle stimulating hormone (FSH,
pituitary), a few of primary follicles start to develop - Follicular cells thicken and multiply into multiple layers
- Follicular cells produce increasing amounts of estrogens as
follicle becomes larger - Fluid-filled spaces form between follicular cells
- Spaces gradually merge into one large fluid-filled space
- When follicle reached its maximum size, it is called mature
follicle, - At this stage estrogen production peaks
Subsequently, surface of mature follicles weakens, ruptures - and release the ova into oviduct
- Fluid released goes along with ovum
- Empty follicle fills with blood after ovum release
- This process is known as ovulation
Ovulation occurs spontaneously in most species as a
result of rising levels of LH (luteinizing hormone from
pituitary gland)
The empty follicles will develop into Corpus luteum - This process is Influenced by continued stimulation of hormone
LH (luteinizing hormone) - Corpus luteum produces hormone progesterone
- Necessary for maintenance of pregnancy
- If ovum implants in uterus, endocrine signal to ovary to cause
corpus luteum to be maintained - If no implantation takes place, the corpus luteum regresses
what are the four stages of the heat cycles in bitches
proestrus (9days)
estrus (9 days, ovulation at day 2)
metestrus (pregenant: 50-60days, not pregnant: 90says)
anestrus (5 months)
what happens during proestrus
female release pheromones to
attract males.
* Female usually does not allow the male to mate
but becomes increasingly receptive.
* There is increased blood concentration of
estrogen causing swelling of the vulva and
* bloody vulval discharge is present.
what happens during estrus
female dog becomes
receptive to mating.
* The female dog may actively seek out
male dogs for mating and may exhibit
behavioural changes like restlessness,
increased urination frequency, and even
changes in appetite
hormones: Estrogen level starts to decline, and
* LH reaches to its peak level and triggers
ovulation (release of the ovum from the
ovary).
* Fertilization can take place if the female
mates with a male dog.
* Corpus luteum forms in place of the
released ovum and secretes progesterone
what happens during metestrus
if fertilization has
occurred, the corpus luteum in ovaries
produce progesterone, which helps
maintain the uterine lining in preparation for
the implantation of fertilized eggs.
* If the female dog does not conceive, she
will enter a non-pregnant diestrus phase in
which the uterine returns to a normal state.
what happens during anestrus
characterized by a lack of ovarian activity and typically
lasts for several months. Anestrus allows the reproductive
system to rest before the next estrus cycle begins.
* In non-pregnant bitch, progesterone level gradually declines
* At late stage of anestrus, some of the primary follicles will
begin to develop to repeat the cycle
what are the different stages of mating
canine mating occurs in estrus stage of heat cycle
First stage (takes around 2 minutes):
The male dog will sit on the female
dog. As dogs will not be able to stay
in this position for long due to severe
cramps that will occur, they will
change position.
The male remains “tied” to the female
after the first stage.
* The turn (takes about 5 seconds):
The males dog achieves this by
swinging one of its hind legs over the
female dog’s body.
* Second stage of mating:
The male and female dog will be standing rear to rear during this stage.
Ejaculation occurs.
The male remains tied to the female for 5 minutes to an hour.
This can be painful for the male as his penis is not in an ideal position,
but you’ve got to let them be and stay around to reassure both dogs
describe the process of fertilisation
The ova released at ovulation are propelled
down the uterine tubes (oviduct).
* At the time of ovulation the ova contain the
haploid number of chromosomes (half the
normal number) and are immature and
incapable of being fertilized.
* They are known as primary oocytes and they
mature to become secondary oocytes
approximately 3 days later.
* During ejaculation sperms are propelled up the
ductus deferens into the urethra, through the
penis and into the female tract.
* The sperm, containing the haploid number of
chromosomes, use their tails to swim from the
vagina through the cervix into the uterus.
* They then enter the uterine tubes where
fertilization takes place.
* Sperm are able to survive within the female tract
for up to 7 days waiting for mature ova to be
available.
Fertilization occurs when a single sperm
penetrates an ovum
* and the nuclei coalesce.
* When a sperm penetrates into the
cytoplasm of the ovum. Further sperms
are prevented from entering by a rapid
chemical change which causes
thickening of the surface of the ovum.
* Fertilization of the ovum by the sperm
results in a zygote, which contains the
diploid number of chromosomes.
* Now the zygote is ready for its first
mitotic division.
describe the process of pregnancy
After fertilization the zygote moves down the uterine tube and by the
time it reaches the uterine horns it has already divided several times.
* It develops a fluid-filled cavity and is known as a blastocyst.
* By about the 19th day the blastocysts space themselves evenly along
the uterine horns and implantation begins.
* In order to create equal numbers within each uterine horn, one or more
blastocysts may cross the body of the uterus to implant in the opposite
horn.
* In the uterus, the endometrium and myometrium
thickens, new blood vessels grow and the endometrium
becomes secretory.
* When the blastocysts reach the uterine horns they are
bathed in the uterine secretions, which provide nutrients
and create the correct environment for survival.
The blastocyst divides and forms an embryo.
* During pregnancy, the female dog’s body undergoes various
physiological changes to support the developing fetuses.
* Hormonal changes occur, with increased production of
progesterone to maintain the pregnancy.
* The female dog may also experience physical changes, such
as
* weight gain,
* enlargement of the abdomen, and
* development of mammary glands.
what are the three different stages of parturition/ describe the process of birth
Stage One:
* This initial stage can last up to 24 hours.
* The female dog may exhibit signs of restlessness, nesting behaviour, and a decrease
in body temperature.
* Uterine contractions begin as the body prepares for labour.
* The cervix gradually dilates to allow the
passage of the puppies
Stage Two:
* Stage Two can last from a few hours to a full day.
* The active delivery of the puppies occurs.
* The uterine contractions intensify, and
* the female dog actively pushes to deliver each puppy.
* The puppies are enclosed in individual amniotic sacs,
which may rupture during delivery.
* The mother typically breaks the sacs, cleans the
puppies, and stimulates their breathing.
* The interval between each puppy’s delivery can vary,
but it usually ranges from 10 minutes to an hour.
Stage Three:
* The final stage involves the delivery of the
placentas or afterbirths.
* After each puppy is born, the placenta that
nourished and protected it during gestation is
expelled.
* The female dog may eat the placentas, which
is a natural behaviour and can provide
nutrients and help clean the whelping area.
