topic 8: reproduction system Flashcards

Question

structure of cervix

Answer 1

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

Answer 2

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.

Answer 3

Receives the penis at breeding, and * Serve as the birth canal at birth

Answer 4

One mature ovum per cycle Horse, cow, human

Answer 5

Multiple ova produced per cycle Cat dog sow (female pig)

Answer 6

* 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

Answer 7

proestrus (9days) estrus (9 days, ovulation at day 2) metestrus (pregenant: 50-60days, not pregnant: 90says) anestrus (5 months)

Answer 8

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.

Answer 9

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

Answer 10

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.

Answer 11

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

Answer 12

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

Answer 13

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.

Answer 14

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.

Answer 15

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.