Spermatogenesis, heat cycle

Question 1

Production of normal numbers of fertile
spermatozoa requires: (4)

Answer 1

– Endocrine regulation of the testis
– Mitotic divisions of spermatogonia

– Meiotic divisions resulting in haploid
spermatids
– Morphologic transformation of spermatids into
spermatozoa

Question 2

where is GnRH recreted from

Answer 2

gondaotropin releasing hormone from the hypothalamus

Question 3

FSH and LH secretion from

Answer 3

the anterior lobe of the pituitary / adenohypophysis

Question 4

what cells produce spermatozoa?

Answer 4

leydig cells

Question 5

testes are composed largely of

Answer 5

seminiferous tubules—coiled tubes, the walls of which contain cells that produce sperm, leydig cells.

Seminiferous tubules may constitute up to 90 percent of the testis.

Question 6

precursor to testosterone in the testes

Answer 6

progesterone

Question 7

Steps of Development of primary gametes in males (5)

Answer 7

Prespermatogenesis
Spermatogenesis
Spermatocytogenesis
Meiosis
Spermiogenesis

Question 8

duration of spermatogenesis

Answer 8

approx. 30- 75 days dependent upon species
so roughly 2-3 months

Question 9

what do the sertoli cells protect spermatozoa from?

Answer 9

the bodies own immune system

Question 10

Semen ingredients

Answer 10

Spermatozoa & Seminal plasma/fluid

Question 11

Seminal plasma is produced by (3)

Answer 11

Accessory sex glands
Epididymis
Ampullary gland

Question 12

What are the accessory organs of the male?

Answer 12

paired ampullary glands
vesicular glands
prostate gland
bulbourethral glands

Question 13

another name for bulbourethral gland and in which species missing and in which, well-developed

Answer 13

Cowper’s glands

absent in ca, well developed in su

Question 14

seminal plasma purposes (5)

Answer 14

Optimal osmotic pressure
Constant pH
Dilution of spermatozoa
Transport media
Stimulates sperm transport in female reproductive tract

Not important for fertility.

Question 14

in which species is the prostate absent and in which, well developed

Answer 14

absent in eq, well developed in car

Question 15

paired vesicular glands contribute what percentage of seminal plasma and contains what?

Answer 15

60%, fructose, ascorbic acid,
prostaglandins

Question 16

what stimulates sperm to begin to swim?

Answer 16

mixing with seminal plasma enzymes

Question 17

Prostate gland contributes what percentage to seminal plasma and contains what imporant component?

Answer 17

5-6 % for bulls

33% enzymes for sperm activation

Question 18

what component of seminal plasma do the Paired bulbourethral glands contribute?

Answer 18

viscous secretion for lubricating female reproductivetract and provides gel fraction in the boar

Question 19

duration of spermatogenesis

Answer 19

man 75 days
bull 61 days
stallion 55
ram 47
boar 39

Question 20

estrus cycle is divided into either

Answer 20

2 or 4 parts

luteal/follicular or

pro-, estrus, met-, di-

Question 21

when estrus is divided into two, what are the two parts:
which one takes up a larger portion of the cycle?

Answer 21

luteal or follicular phase

follicular phase is shorter (approx. 20%)

(corpus luteum development and follicular development)

Question 22

name the stages of the estrus cycle

Answer 22

proestrus 18-21 days
estrus 1-2 days
metestrus 2-5 days
diestrus 5-18 days
(anestrus e.g. during pregnancy)

the days here apply to bovine

Question 23

how quickly after calving does a cow begin to cycle again

Answer 23

2-3 months

“Mature cows usually take about 60 days to come on heat again after calving; young cows may take 90 days or more.”

Question 24

how quickly after foaling do mares begin to cycle again

Answer 24

Postpartum mares will have a “foal heat” 7 to 14 days following foaling, and a second cycle approximately 30 days later. Breeding on foal heat is still somewhat of a controversial practice.

Question 25

how quickly after farrowing do sows begin to cycle again

Answer 25

sows experience lactation anestrus factory farmed piglets are weaned at approx. 21-28 days old after weaning the sows typically come into heat again in 3-5 days

Question 26

how quickly after lambing do sheep begin to cycle again

Answer 26

the following autumn Ewes are seasonally polyestrous, cycling every 16–17 days during the breeding season.

Question 27

in which month of gestation does the CL regress in equine

Answer 27

3-5 months as the placenta begins to produce progesterone "Individual CL appear to regress at different times in the same ovaries of individual pregnant mares after Day 100 of gestation."

Question 28

features of proestrus (3)

Answer 28

growth of preovulatory follicles increase in estrogen, estradiol peak at end of proestrus endomtetrial development

Question 29

features of metestrus (5)

Answer 29

in cows ovulation occurs during metestrus, not estrus like in other species estrogens go low corpus hemorrhagicum develops uterine contractions and some vaginal bleeding can occur fsh stimulates follicular growth

Question 30

features of diestrus (4)

Answer 30

is longest period of cyclicity. progesterone is high FSH develops 2nd wave follicles no uterine contractions involution of CL if no pregnancy -> release of PGF2alfa

Question 31

why do bovine experience some vaginal bleeding during metestrus

Answer 31

estrogen withdrawl's effect on blood vessel permeability, is considered physiological. 17-18 days post bleeding, heat should occur again (full cycle is 21 days)

Question 32

how long does a CL persist in bitches?

Answer 32

2 months ish

Question 33

length of estrus in dog

Answer 33

five to nine days many sources say up to 2 weeks but that includes proestrus which is difficult to diffrentiate from estrus dogs ovulate an immature oocyte

Question 33

what estrus phase is unique to cats?

Answer 33

"postestrus" because cats are induced ovulators

Question 34

cat gestation duration

Answer 34

58-60 days other sources say 63-65 days

Question 35

How soon after giving birth can a cat go into heat?

Answer 35

Most queens will return to estrus about 4 weeks after weaning their kittens if it is still the breeding season. However, it is entirely possible for a queen to return to estrus while still nursing.

Question 36

horse gestation

Answer 36

11 months (10-12)

Question 37

name 3 polyestrus animals

Answer 37

sow cow cat (or seasonally)

Question 38

name seasonally polyestrus long day breeder

Answer 38

horses begin to come intro estrus as days grow longer in the springtime. (so foals are typically born the following spring)

Question 39

name a seasonally polyestrus short day breeder

Answer 39

sheep begin to come into estrus as days grow shorter in the autumn (so lambs are born the following spring, approx. 5 months later)

Question 40

name 3 monoestrus animals

Answer 40

dog wolf bear (even thought some dogs may cycle twice per year)

Question 41

what percentage of spermatozoa is typically 'imperfect'

Answer 41

approx. 20%

Question 42

how are spermatozoa defects classified

Answer 42

primary secondary tertiary

Question 43

seasonally polyestrus species cycles are regulated by what hormone

Answer 43

melatonin

Question 44

ewe estrus cycle length? duration of heat?

Answer 44

17 days 24-36 hours

Question 45

mare estrus cycle length? duration of heat?

Answer 45

21 days 3-8 days

Question 46

sow duration of heat?

Answer 46

48-72 hours

Question 47

bitch duration of heat?

Answer 47

9 days (same goes for queen)

Question 48

when might cows experience bloody vulvar discharge?

Answer 48

1-4 days after heat and approx. 18 days before next ovulation (?) due to estrogen's effects on vaginal membrane permeability.

Question 49

when are cows typically inseminated afetr parturition?

Answer 49

50-55 days after parturition some variation can occur of course, but 3 months is considered too long and insemination at the first post-parturition heat is a bit too soon.