Exam 3

Question 1

True or False: In almost all species studied including humans, there is a marked increase in physical activity around the time of ovulation

Answer 1

True

Question 2

True or False: The bull and ram and dog are short copulators while the boar, tom cat, and camelids are sustained copulators

Answer 2

False

Question 3

True or False: Prenatal exposure of a female fetus to a large dose of estradiol results in decreased estrous behavior and an increase in male-like behavior

Answer 3

True

Question 4

True or False: Sexual preparation in the bull, increases sperm numbers in the ejaculate through oxytocin release from the posterior pituitary which stimulates contractions of the distal tail of the epididymis and ductus deferens

Answer 4

True

Question 5

True or False: When collecting see from a bull with an artificial vagina, both temperature and pressure are important to stimulate ejaculation, while only an optimal temperature is required for the boar

Answer 5

False

Question 6

True or False: Viagra causes a prolonged erection because it inhibits the conversion of cGMP to GMP thus prolonging vasodilation

Answer 6

True

Question 7

True or False: Following AI in cows, less sperm are lost by retrograde flow if they are deposited in the mid-cervix than if they are deposited in the uterus

Answer 7

False

Question 8

True or False: Superfecundation in dog is a result of their long duration of estrus and the prolonged interval after the onset of estrus when fertilization can occur

Answer 8

True

Question 9

True or False: During the acrosome reaction fusion of sperm plasma membrane and outer acrosomal membrane leads to vesiculation and loss of the acrosomal enzymes

Answer 9

True

Question 10

True or False: Acrosin, an enzyme released during the acrosome reaction allows the sperm to penetrate the vitelline membrane

Answer 10

False

Question 11

True or False: Zona protein 3 (ZP3) is a glycoprotein receptor which only allows sperm of the same species to bind to the zone pellucid

Answer 11

True

Question 12

True or False: In most mammalian species sperm capacitation occurs in the male accessory sex glands prior to ejaculation

Answer 12

False

Question 13

True or False: During cervical transport, viable sperm that encounter high viscosity sialomucin swim through the cervix with ease, while sperm encountering the low viscosity sialomucin are flushed out of the tract

Answer 13

False

Question 14

True or False: Loss of sperm from the female tract occurs mainly through the process of phagocytosis and retrograde flow

Answer 14

True

Question 15

True or False: The primary oocyte undergoes the first meiotic division at ovulation in cattle, sheep, and pigs, while the second meiotic division occurs at the time of fertilization

Answer 15

True

Question 16

True or False: Each blastomere (embryonic cell) of an 4 cell pig embryo and an 8 cell cow embryo are totipotent

Answer 16

True

Question 17

True or False: A morula is a solid ball of blastomeres, while a blastocyst contains inner cell mass cells surrounded by trophectoderm cells and a fluid filled cavity called the blastocoele

Answer 17

True

Question 18

True or False: The trophectoderm cells surrounding the blastocyst develop gap junctions between them to allow a free exchange of information, while the inner cell mass cells develop tight junctions to hold the inner cell mass together

Answer 18

False

Question 19

True or False: The collection of embryos from the uterus of donor cows and their transfer into recipient females should only be done after hatching of the blastocysts from the zona pellucida

Answer 19

False

Question 20

True or False: If inner cell mass cells from a goat blastocyst are collected and injected into the blastocyst of a sheep embryo containing its own inner cell mass, and the injected embryo placed into the uterus of a goat, it will give birth to a deep (cross between sheep and goat)

Answer 20

False

Question 21

urethralis muscle

Answer 21

propels sperm + seminal plasma (semen) through the pelvic urethra

Question 22

Bulbospongiosus muscle

Answer 22

pumps semen from the pelvic urethra through the penile urethra

Question 23

ischiocavernousus muscle

Answer 23

clamps off venous return from the penis resulting in penile extension

Question 24

Yolk sac

Answer 24

• develops the first blood vessels in the conceptus and is called the primitive gut
• splanchnic mesoderm + endoderm

Question 25

Allantois

Answer 25

* -thrust out from the hind gut of the embryo, and expands to vascularize the chorion * splanchnic mesoderm + endoderm

Question 26

Chorion

Answer 26

* not vascularized and acts as a protective outer covering of the conceptus * somatic mesoderm + trophectoderm

Question 27

Amnion

Answer 27

* a high pressure bubble which surrounds the embryo to prevent it from being crushed by uterine contractions * somatic mesoderm + trophectoderm

Question 28

necrotic tips form at each end of an elongating pig embryo when these parts of the placenta fail to fuse together

Answer 28

1. Allantois 2. Chorion

Question 29

this part regresses at implantation when the choir-allantonic membrane forms and attaches to the uterine wall to begin to take up nutrients directly from the maternal blood

Answer 29

Yolk Sak

Question 30

the umbilical cord forms at the sight where this part of the placenta grew out of the embryo

Answer 30

Allantois

Question 31

**goat** * signal that maintains luteal function in specie during maternal recognition of preg. * CL indep. or dep.

Answer 31

1. interferon?? 2. Cl dependent specie

Question 32

**women** * signal that maintains luteal function in specie during maternal recognition of preg. * CL indep. or dep.

Answer 32

1. hCG 2. CL independent specie

Question 33

**sheep** * signal that maintains luteal function in specie during maternal recognition of preg. * CL indep. or dep.

Answer 33

1. interferon 2. CL independent specie

Question 34

**pig** * signal that maintains luteal function in specie during maternal recognition of preg. * CL indep. or dep.

Answer 34

1. estradiol 2. CL dependent specie

Question 35

**cow** * placental type * number of tissue layers separating fetal and maternal blood stream * placental shape

Answer 35

1. syndesmochorial placenta 2. five layers 3. cotyledonary shaped

Question 36

**mare** * placental type * number of tissue layers separating fetal and maternal blood stream * placental shape

Answer 36

1. eptheliochorial placenta 2. six layers 3. diffuse shaped

Question 37

**dog** * placental type * number of tissue layers separating fetal and maternal blood stream * placental shape

Answer 37

1. endotheliochorial placenta 2. four layers 3. zonary shaped

Question 38

**woman** * placental type * number of tissue layers separating fetal and maternal blood stream * placental shape

Answer 38

1. hemochorial placenta 2. three layers 3. discoid shaped

Question 39

female which requires the greatest area of association between the placental and the uterine wall per unit weight fetus for nutrient uptake from the mother

Answer 39

mare

Question 40

female in which endometrial cups are developed to stimulate the development of accessory corpora lutea

Answer 40

mare

Question 41

females whose young do not have an absolute requirement for colostrum if they are to survive

Answer 41

1. woman 2. dog

Question 42

females with decidua

Answer 42

1. woman 2. dogs( not true decidua)?

Question 43

female where the chorionic epithelium is bathed in maternal blood

Answer 43

woman

Question 44

female which forms binucleate cells which migrate out of the chorionic epithelium into the uterine luminal epithelium and secrete placental lactogen

Answer 44

cow

Question 45

Why does the cow commonly exhibit retained placentae following premature births or late term abortions while the sheep does not. Be specific

Answer 45

Although both species have cotyledonary placentas the ewe (and goats) have *concave cotyledons*, whereas in the cow (and giraffe) the *cotyledons are convex*. The convex shape leads to a greater susceptibility to retaining the placenta since it is more difficult to separate maternal and fetal tissue

Question 46

forms the postnuclear cap

Answer 46

manchette

Question 47

forms proacrosomal granules

Answer 47

golgi saccules

Question 48

gives rise to the attachment site for the sperm tail

Answer 48

proximal centriole

Question 49

gives rise to the axoneme

Answer 49

distal centriole

Question 50

spiral around the middle piece of the sperm tail

Answer 50

mitochondria

Question 51

provide stability to the sperm tail

Answer 51

nine fibers surround the axoneme

Question 52

forms the cap of the sperm head and contains hydrolytic enzymes

Answer 52

acrosome

Question 53

list the requirements of a good semen extender used for artificial insemination

Answer 53

1) minimize cold shock 2) prevent microbial growth 3) maintain viability 4) low in cost 5) be isotonic 6) be a good buffer 7) provide nutrients

Question 54

stimulates the leydig cells to produce testosterone

Answer 54

LH

Question 55

natural male hormone that exerts a negative feedback on GnRH secretion from the tonic release center of the hypothalamus

Answer 55

testosterone

Question 56

man-made hormone administered to promote muscle growth and performance

Answer 56

anabolic steroid

Question 57

stimulates androgen binding protein production by sertoli cells

Answer 57

FSH

Question 58

inhibits FSH secretion by the anterior pituitary gonadotrophs

Answer 58

inhibin

Question 59

this hormone binds to receptors on sertoli cells and maintains spermatogenesis at an optimal level

Answer 59

FSH

Question 60

this hormone stimulates sex drive and maintenance of the male genital duct system and through conversion to DHT promotes a male phenotype

Answer 60

testosterone

Question 61

when administered in high doses over a prolonged period it will kill the leydig cells resulting in sterility

Answer 61

anabolic steroid

Question 62

True or False: Lochia is necrotic placental and endometrial remnants left over after pregnancy which is expelled through the vulva

Answer 62

True

Question 63

True or False: the time required for uterine involution is less for the dairy cow than the suckled beef cow

Answer 63

False

Question 64

True or False: Resumption of ovarian activity occurs sooner in the dairy cow than in the suckled beef cow

Answer 64

True

Question 65

True or False: What differentiates mammals from other groups of animals is live birth and the presence of a mammary gland

Answer 65

False

Question 66

True or False: Elephants have paired mammary glands on the thoracic regions on the mammary ridges

Answer 66

True

Question 67

True or False: From birth to conception the mammary glands grow at the same rate as the rest of the body, but after puberty they begin to grow at an increased rate under the stimulus of estradiol (duct development) and progesterone (glandular development).

Answer 67

True

Question 68

True or False: Colostrum is a result of increased pressure in the lumen of alveoli prior to offspring suckling which breaks the tight junctions between the mammary secretory cells

Answer 68

True

Question 69

True or False: Rennin is secreted by the gastric epithelium of very young ruminants and causes milk proteins (caseins) to form curds to facilitate protein digestion

Answer 69

True

Question 70

True or False: The composition of alveolar milk is changed significantly as it travels through the duct system to the teat

Answer 70

False

Question 71

True or False: The secretion of milk protein and lactose by the mammary secretory cell into the alveolar lumen removes part of its apical cell membrane which is replaced by the secretion of milk fat

Answer 71

False

Question 72

Fully discuss, how **increased cortisol production** by the bovine fetal adrenal prepares the fetus for life outside the uterus, and how this elevated fetal cortisol initiates the hormonal events resulting in cervical softening, delivery of the fetus and delivery of the placenta during the process of parturition. Be specific about the _source of the hormones_, and the _location of their receptors_ in the gravid uterus.

Answer 72

1. **Step 1: Preparatory Phase (cervical softening and initiation of myometrial contractions)** 1. as fetal cortisol continues to increase it causes 1. a _decrease in progesterone_ production by the placenta and/or CL 2. an _increase in PGF2alpha_ by the uterine endometrium and placenta 3. the _increase in PGF2alpha and estradiol_ abolish the progesterone block --\> myometrium begins to contract 4. _PGF2alpha_ also kills the CL of all species, causing a further decline in progesterone and the dying CL releases _relaxin_ which softens the cervix and opens the birth canal by opening the pelvic ligament 2. **Step 2: Expulsion of the Fetus** 1. _increased estrogen_ causes the development of gap junctions between mymetrial cells and increases nubmers of _PGF2alpha and oxytocin_ receptors on the myometrial cells --\> initiation of directional uterine contractions 2. Fetus is pushed against the inside of the cervix, _exposing sensory receptors signaling oxytocin release._ 3. Oxytocin stimulates powerful peristaltic contractions which ruptures the allantois 4. Fetus is forced into the birth canal and amnion ruptures 5. Ab muscles finish expelling fetus via contractions 3. **Step 3: Expulsion of Fetal Membranes** 1. Expulsion of fetal membranes requires that chorionic villi become dislodged from the crypts on the maternal side of the placenta 2. requires continued uterine contractions--\> _oxytocin release_

Question 73

Describe the sequence of hormonal events which time lactogenesis (initiation of milk secretion) with the delivery of the calf at parturition the cow. (Hint: Remember that progesterone progressively declines over the last week of gestation in the cow.)

Answer 73

1. a couple weeks before parturition, progesterone decreases thus causing the stimulation of corticosteriod binding globulin by the liver to decrease 2. as free cortisol is increased in the blood, it enters and begins to differentiate mammary secretory cells 3. placental estradiol levels begin to increase markedly in the blood which increases pituitary secretion of prolactin but prevents it from binding to its receptors on mammary secretory cells 4. at parturition, the placenta is expelled and estradiol levels drop, allowing prolactin to bind to mammary secretory cells and stimulate lactose synthesis. 5. As lactose is synthesized within the mammary secretory cells, they draw in water by osmosis which initiates milk secretion

Question 74

What are the 4 major events of the puerperium?

Answer 74

1. myometrial contractions and expulsion of 2. endometrial repair 3. resumption of ovarian function 4. elimination of bacterial contamination of the reproductive tract

Question 75

Mammogenesis definition

Answer 75

* growth and development of the gland between birth and puberty * between birth and puberty, growth is isometric * between puberty and conception growth is allometric

Question 76

Lactogenesis

Answer 76

intitation of milk secretion at term and results from hormonal changes

Question 77

Colostrum

Answer 77

first secretions from the mammary gland * rich in immunoglobins

Question 78

what do immunoglobins do for offsring

Answer 78

passive immunity to offspring

Question 79

how is colostrum formed

Answer 79

high pressure within the mammary duct system, which breaks in tight junctions between the mammary secretory cells in alveoli allowing blood plasma to enter alveolar lumen

Question 80

how does milk ejection happen

Answer 80

When sensory neurons in the teat or nipple are stimulated by tactile stimuli, a neural signal is sent to the interneuron of the spinal cord which convey the signal to paraventricular nucleus which results in oxytocin release from posterior pituitary into blood