Non-pregnant female reproductive physiology quiz

WIKIQUIZ

Questions reviewed by:

Peter G.G. Jackson BVM&S, MA, DVM&S, FRCVS David Bainbridge, VetMB MA PhD MRCVS David Kilroy MVB CVMA MRCVS

1

Which single cell in the female is haploid? Primary oocyte Secondary oocyte Blastomere Zygote Oogonium Please select an option Incorrect. A primary oocyte is formed when a diploid oogonium undergoes mitosis, thereby creating cells with a full complement of chromosomes i.e. diploid cells. A secondary oocyte is formed when a primary oocyte undergoes meiosis, therefore it has half the number of chromosomes making it haploid. WikiVet Article: embryonic development of the blastocyst. Correct! A secondary oocyte is formed when a primary oocyte undergoes meiosis, therefore it has half the number of chromosomes making it haploid. WikiVet Article: embryonic development of the blastocyst. Incorrect. A blastomere is formed when the zygote undergoes mitosis thereby creating cells with a full complement of chromosomes i.e. diploid cells. A secondary oocyte is formed when a primary oocyte undergoes meiosis, therefore it has half the number of chromosomes making it haploid. WikiVet Article: embryonic development of the blastocyst. Incorrect. A zygote is formed when the male and female pronuclei fuse resulting in a single diploid nucleus. A secondary oocyte is formed when a primary oocyte undergoes meiosis, therefore it has half the number of chromosomes making it haploid. WikiVet Article: embryonic development of the blastocyst. Incorrect. An oogonium is produced when a primordial germ cell (which is diploid) undergoes mitosis thereby creating cells with a full complement of chromosomes i.e. diploid cells. A secondary oocyte is formed when a primary oocyte undergoes meiosis, therefore it has half the number of chromosomes making it haploid. WikiVet Article: embryonic development of the blastocyst

2

Which hormone causes luteolysis in ruminants? Oestrogen Progesterone Oxytocin Prolactin Prostaglandin F2α (PGF2α) Please select an option Incorrect. Oestrogen promotes development of mammary tissue and is vital for thickening of the endometrium prior to implantation. Oestrogens regulate the oestrus cycle. PGF2α from the endometrium is transported to the ipsilateral ovary through a vascular counter-current exchange mechanism. This ensures a high proportion of PGF2α produced by the uterine glands will be transported directly to the ovary and corpus luteum without dilution in the systemic circulation, thereby causing luteolysis. WikiVet Article: luteolysis. Incorrect. Progesterone converts the endometrium to its secretory stage to prepare for implantation, reduces the immune response within the uterus to allow for acceptance of the conceptus, and decreases contractility of the smooth muscle. PGF2α from the endometrium is transported to the ipsilateral ovary through a vascular counter-current exchange mechanism. This ensures a high proportion of PGF2α produced by the uterine glands will be transported directly to the ovary and corpus luteum without dilution in the systemic circulation, thereby causing luteolysis. WikiVet Article: luteolysis. Incorrect. In addition to allowing milk let-down and promoting uterine contractions, oxytocin works along with oestrogen to induce endometrial production of prostaglandin F2α resulting in luteolysis. WikiVet Article: luteolysis. Incorrect. Prolactin acts on mammary secretory epithelial cells to stimulate synthesis of milk proteins. It is released during suckling and in response to the rise in oestrogen and glucocorticoids in parturition. PGF2α from the endometrium is transported to the ipsilateral ovary through a vascular counter-current exchange mechanism. This ensures a high proportion of PGF2α produced by the uterine glands will be transported directly to the ovary and corpus luteum without dilution in the systemic circulation, thereby causing luteolysis. WikiVet Article: luteolysis. Correct! PGF2α from the endometrium is transported to the ipsilateral ovary through a vascular counter-current exchange mechanism. This ensures a high proportion of PGF2α produced by the uterine glands will be transported directly to the ovary and corpus luteum without dilution in the systemic circulation, thereby causing luteolysis. WikiVet Article: luteolysis.

3

In the mare, how will melatonin and gonadotrophin-releasing hormone (GnRH) production change as daylight increases? Increased secretion of melatonin from the pineal gland and increased GnRH from the hypothalamus. Increased secretion of melatonin from the pineal gland and decreased GnRH from the hypothalmus. Decreased secretion of melatonin from the pineal gland and increased GnRH from the hypothalamus. Decreased secretion of melatonin from the pineal gland and decreased secretion of GnRH from the pituitary gland. Decreased secretion of melatonin from the pineal gland and decreased GnRH from the hypothalamus. Please select an option Incorrect. Increased light leads to increased retinal firing and in turn increased firing of the nerves of the cranial cervical ganglia. This has an inhibitory effect on the pineal gland which secretes melatonin. Melatonin has an inhibitory effect on the hypothalamus (in long day breeders, as opposed to short day breeders) therefore less melatonin is released leading to more GnRH and therefore more FSH and LH from the pituitary thereby inducing ovulation. WikiVet Article: pineal gland. Incorrect. Increased light leads to increased retinal firing and in turn increased firing of the nerves of the cranial cervical ganglia. This has an inhibitory effect on the pineal gland which secretes melatonin. Melatonin has an inhibitory effect on the hypothalamus (in long day breeders, as opposed to short day breeders) therefore less melatonin is released leading to more GnRH and therefore more FSH and LH from the pituitary thereby inducing ovulation. WikiVet Article: pineal gland. Correct! Increased light leads to increased retinal firing and in turn increased firing of the nerves of the cranial cervical ganglia. This has an inhibitory effect on the pineal gland which secretes melatonin. Melatonin has an inhibitory effect on the hypothalamus (in long day breeders, as opposed to short day breeders) therefore less melatonin is released leading to more GnRH and therefore more FSH and LH from the pituitary thereby inducing ovulation. WikiVet Article: pineal gland. Incorrect. Increased light leads to increased retinal firing and in turn increased firing of the nerves of the cranial cervical ganglia. This has an inhibitory effect on the pineal gland which secretes melatonin. Melatonin has an inhibitory effect on the hypothalamus (in long day breeders, as opposed to short day breeders) therefore less melatonin is released leading to more GnRH and therefore more FSH and LH from the pituitary thereby inducing ovulation. WikiVet Article: pineal gland. Incorrect. Increased light leads to increased retinal firing and in turn increased firing of the nerves of the cranial cervical ganglia. This has an inhibitory effect on the pineal gland which secretes melatonin. Melatonin has an inhibitory effect on the hypothalamus (in long day breeders, as opposed to short day breeders) therefore less melatonin is released leading to more GnRH and therefore more FSH and LH from the pituitary thereby inducing ovulation. WikiVet Article: pineal gland.

4

Which hormone is produced by the endometrium? Oestrogen Progesterone Oxytocin Prolactin Prostaglandin F2α (PGF2α) Please select an option Incorrect. Oestrogen is produced by the granulosa cells of the follicle and the placenta. In response to increasing amounts of oxytocin production by the corpus luteum during the luteal phase, the endometrium produces luteolytic prostaglandin F2α (PGF2α) to cause degeneration of the corpus luteum if the female is not pregnant. WikiVet Article: the uterus. Incorrect. Progesterone is produced by the corpus luteum and later on by the placenta. In response to increasing amounts of oxytocin production by the corpus luteum during the luteal phase, the endometrium produces luteolytic prostaglandin F2α (PGF2α) to cause degeneration of the corpus luteum if the female is not pregnant. WikiVet Article: the uterus. Incorrect. Oxytocin is produced by the corpus luteum during the luteal phase and the endometrium responds by producing luteolytic prostaglandin F2α (PGF2α) to cause degeneration of the corpus luteum if the female is not pregnant. WikiVet Article: the uterus. Incorrect. Prolactin is produced by the lactoroph cells of the anterior pituitary. In response to increasing amounts of oxytocin production by the corpus luteum during the luteal phase, the endometrium produces luteolytic prostaglandin F2α (PGF2α) to cause degeneration of the corpus luteum if the female is not pregnant. WikiVet Article: the uterus. Correct! In response to increasing amounts of oxytocin production by the corpus luteum during the luteal phase the endometrium produces luteolytic PGF2α to cause degeneration of the corpus luteum if the female is not pregnant. WikiVet Article: the uterus.

5

What is the average length of the oestrous cycle in the cow? 20 days 21 days 28 days 36 days 17 days Please select an option Incorrect. In heifers, the average length of the oestrous cycle is 20 days (18-22). In cows, the average length of the oestrous cycle is 21 days (18-24). WikiVet Article: oestrous cycle. Correct! In cows, the average length of the oestrous cycle is 21 days (18-24). In heifers, the average length of the oestrous cycle is 20 days (18-22). WikiVet Article: oestrous cycle. Incorrect. In cows, the average length of the oestrous cycle is 21 days (18-24). WikiVet Article: oestrous cycle. Incorrect. In cows, the average length of the oestrous cycle is 21 days (18-24). WikiVet Article: oestrous cycle. Incorrect. In ewes the average length of the oestrous cycle is about 17 days. In cows, the average length of the oestrous cycle is 21 days (18-24). WikiVet Article: oestrous cycle.

6

What is the average length of the oestrous cycle in the ewe? 28 days 36 days 17 days 93 days 21 days Please select an option Incorrect. In the ewe, the average length of the oestrous cycle is 17 days. WikiVet Article: oestrous cycle. Incorrect. In the ewe, the average length of the oestrous cycle is 17 days. WikiVet Article: oestrous cycle. Correct! In the ewe, the average length of the oestrous cycle is 17 days. WikiVet Article: oestrous cycle. Incorrect. The oestrous cycle is on average 93 days in the bitch. In the ewe, the average length of the oestrous cycle is 17 days. WikiVet Article: oestrous cycle. Incorrect. The oestrous cycle is 21 days in the mare, sow and cow. In the ewe, the average length of the oestrous cycle is 17 days. WikiVet Article: oestrous cycle.

7

Which species is a short day breeder? Cat Dog Sheep Cow Horse Please select an option Incorrect. Cats are seasonally polyoestrus. Sheep are short day breeders, they start cycling in response to a decreasing photoperiod usually at the end of summer or beginning of autumn. WikiVet Article: seasonality of reproduction. Incorrect. Seasonality does not affect reproductive cycling in dogs. Sheep are short day breeders, they start cycling in response to a decreasing photoperiod usually at the end of summer or beginning of autumn. WikiVet Article: seasonality of reproduction. Correct! Sheep start cycling in response to a decreasing photoperiod usually at the end of summer or beginning of autumn. WikiVet Article: seasonality of reproduction. Incorrect. Seasonality does not affect reproductive cycling in cattle. Sheep are short day breeders, they start cycling in response to a decreasing photoperiod usually at the end of summer or beginning of autumn. WikiVet Article: seasonality of reproduction. Incorrect. Horses are long day breeders so they start cycling as the photoperiod increases, in the northern hemisphere this occurs in April - June. This photoperiod can be manipulated to alter the timing of the breeding system which is particularly important in producing foals for the racing industry. Racehorses run from the age of two years old, with the age of the horse being measured from the 1st of January. Producing horses born as close to the 1st of January as possible gives them a performance advantage when racing. Sheep are short day breeders, they start cycling in response to a decreasing photoperiod usually at the end of summer or beginning of autumn. WikiVet Article: seasonality of reproduction.