QUESTIONS

1. Prolactin comes from which side of the pituitary? What controls its release?
    
2. Milk removal is VIP for continued lactation. Suckling represents "passive removal."  What is "active removal?"
    
3. Many hormones involved in lactation are also involved in parturition. What is prolactin's role in parturition?
    
4. What are the sources of progesterone?  What are the sources of estrogen?
    
5. For each statement put an E for estrogen, a P for progesterone & an EP for both.
   
   increases growth of the endometrial glands
   increases growth of the mammary glands
   increases secretion in the oviduct so as to promote survival of the
        ova & sperm
   promotes anterior pituitary gonadotropin secretion
   promotes psychic estrus in the bitch (& ewe)
   causes PGF2-alpha release from the uterus
   decreases uterine contraction in pregnancy
   suppresses gonadotropin release
   closes physeal plates
    
6. What hypothalamic product controls the release of FSH & LH?
    
7. What happens in the follicular phase of follicle growth?
    
8. Since cats are induced ovulators, how does ovulation work in this species?
    
9. How long does a CL last in a non-pregnant dog? How long does it last in  a pseudopregnant cat?
    
10. Signify whether each statement below applies to Proestrus, estrus, diestrus or anestrus (in the dog):
    
    Vaginal bleeding
    Male is allowed to mount
    Heightened follicular activity
    Phase of estrogen dominance
    Phase of declining estrogen
    Stage where progesterone peaks
     
11. True or False: The CL of a pregnant bitch lasts longer than the CL of a non-pregnant bitch.
     
12. How long is a lady cat in estrus?
     
13. When in the cat does the CL poop out & let the placenta take over progesterone production?
    
    
    
    
     

ANSWERS

1. Prolactin comes from the anterior pituitary. It is released in response to suckling & is inhibited by dopamine.
   
   
   
   
    
2. Active milk removal is the oxytocin-mediated contraction of myoepithelial cells leading to the forcing out of milk.
   
   
   
   
    
3. Trick question.  Prolactin is a hormone that does not have a role in parturition. (FYI, prolactin is luteotropic in the rat, mouse & ewe)
   
   
   
   
    
4. Sources of progesterone = CL, placenta, adrenal cortex
   
   Sources of estrogen = ovary(follicle/granulosa cells), feto-placental unit, & adrenal cortex.
   
   
   
   
    
5. increases growth of endometrial glands: EP
   increases growth of mammary glands: EP
   increases oviduct secretion: EP
   promotes ant. pit. gonadotropin release: E
   promotes psychic estrus in the bitch: P
   causes PGF2-alpha release: E
   decreases uterine contraction: P
   suppresses gonadotropin release: P
   closes physeal plates: E
   
   
   
   
    
6. The hypothalamic product is GNRH also called LHRH. The pituitary under the influence of estrogen is sensitized to GnRH, under the influence of progesterone, it is desensitized.
   
   
   
   
    
7. OK, FSH (from the pituitary) causes the granulosa cells to convert androgens produced by the theca into estrogens.  FSH also causes proliferation of FSH receptors in the granulosa cells so that the follicle becomes more & more sensitive to FSH which in turn leads to rampant estrogen production.  The estrogens cause the granulosa cells to divide which leads to still more FSH receptors. Estrogens & FSH together lead to secretions which form the antral cavity.  The granulosa cells also produce factors which prevent premature luteinization (keeping the whole process well coordinated).  You'd think at this rate that the whole female animal would soon turn into one big follicle and that some kind of nuclear estrogen accident would occur but here's what stops the process:
   
   FSH is also inducing LH receptors in the granulosa cells.  The end comes when sustained high estrogen levels lead to the famous pre-ovulatory LH surge.  The follicle ruptures & luteinization begins. In most species the LH surge lasts only a few hours (in the mare it lasts up to 7 days, though).
   
   
   
   
    
8. Vaginal stimulation initiates LH via sensory pathways in the spinal cord.  Cats, however, often do not match their behavioral estrus well w/their ovaries so there may not be a ripe follicle to ovulate when the LH surge comes thus, in this case, there would be no ovulation.  Other induced ovulators include minks, ferrets & rabbits.
   
   
   
   
    
9. The CL lasts approx 75 days in the non-pregnant dog & 35-37 days in the pseudopregnant cat. In the cat, there is a 7-10 day interestrous period after the 35-37 days before heat begins again.  In large animals, the CL is acutely lysed whereas in small animals it gradually wears out.
   
   
   
   
    
10. Vaginal bleeding - Proestrus
    Male is allowed to mount-Estrus
    Heightened follicular activity - Proestrus
    Phase of estrogen dominance - Proestrus
    Phase of declining estrogen - Estrus
    Stage where progesterone peaks - Diestrus
    
    
    
    
     
11. False. The non-pregnant CL lasts 75 days. The bitch is only pregnant for 63 days.
    
    
    
    
     
12. Lady cats are in estrus approx. 6 days. If they are not bred, they stay in estrus 8.5 days on the average. There is an 8 day interestrous period unless they are pseudopregnant.
    
    
    
    
     
13. Cats are pregnant 64 days or so. By day 50 the CL has pooped out & the placenta is doing the job.