Lecture 37

• within one minute post-ejaculation the seminal plasma coagulates in the vagina
  
• -the semen contains fibrinogen which it got from seminal vesicle and it has a clotting enzyme it got from the prostate which can change fibrinogen to fibrin and the two mix during ejaculation
  

  -the prostate also puts out profibroglycin in and this is quickly activated
  

  -coagulin breaks down 20-30 minutes
  

  -gelling of the plasma for this short time helps the semen stay in place until cervix drops down into it
  

  -three types of sperm
  

  -seekers: trying to fertilize oocyte, vast minority of the sperm, move about 3mm/min, which is about 0.001 mph
  

  -killers: swim, kill very quickly, kill sperm from other males
  

  -blockers: don't swim very well at all, crooked tails, link tails to fill crevices in vagina, only pass same male sperm
  

  -as the sperm move through the female tract they become capacitated (capacitation is sometimes considered a maturation of the sperm, the removal of glycoproteins and other proteins from the head of the sperm, enahcnes their ability to adhere ot the oocyte and release hydrolytic enzymes, takes 7 hours)
  

  -when sperm reach isthmus of the fallopian tube, they stop being hypermobile and their mobility is greatly reduced, they are drawn there by a chemotaxic factor release by the ovum
  

  -some sperm go on and head to oocyte but most sperm are stored in the isthumus of the fallopian tube until ovulation and when it occurs the sperm become hypermobile again, the sperm will be released and fertilize the oocyte, fertilization usually takes place in the ampulla
  

  -avg ejaculation is ~3.5mL and average sperm count is 120 million/mL
  

  -semen can be as high as 6mL in volume
  

  -sperm count can be as high as 250million/mL, but using the averages during sexual intercourse 420million sperm are deposited in the vagina
  

  -100million die immediateily
  

  -a few thousand reach the fallopian tube, only 50-100 will reach the oocyte
  

   
   

  Female Sexual Cycle
  

  • Female sexual cycle is divided into ovarian cycle and uterine cycle –
    

  Ovarian cycle
  

  • Follicular phase – when early teriary follicles are stimulated to mature until 1 ovulates - already reached tertiary stage before they are stimulated
    
  • Ovulation
    
  • Leuteal phase – corpus leudium is secreting hormones including  progesterone (big one )
    

  Uterine cycle
  

  • The uterine cycle starts with menses – this is the menstruation – this is passing blood from the vagina – this starts with blood vessels of functional layer becoming neurcrotic and they open up and blood seems into the functional layer itself – this layer then shluffs off down to the site of the hemorrhages -  Fibro bysin is stopping blood clots form happening – the blood and tissue are passed out of the body via the vagina – called menstruation – the first day of menstruation is considered first day of womans cycle –
    
  • Proliferative Phase - The uterine cycle then goes into this – this is when the functional layer of endometrial is built and thickens – but cervical lining doesn't thicken – however cervical mucus thins and becomes more alkaline so it is more favorable for sperm
    
  • Secratory phase – during this phase the thickening of the endometrium is stopped – it now secretes a glygogen rich nutrient solution and prolactin – this feeds fertilized oveum until implantation occurs – role of prolactin unkown
    
    • LHRH /FSHRS – are pulsatile – different at different ages – after puberty become pulsitile again - LH or FSH become secreted - pulse on apprx. 1 hour cycle – however cycles aren't synchronized - the pulsatile burst are more frequent in follicular phase than leuteal phase – during the follicular phase – LH – FSH production are greatly stimulated in the anterior pituitary – however release is held to low levels by estrogen – thus a store of FSH and LH build up in the anterior pituitary
      
    • During follicular phase the number of theca interna and granulosa cells greatly increase – 6-12 follicles are growing 1 will ovulate – the increasing number of these cells produces higher and higher levels of estrogen until it gets to 200-300 pg/ml – and stays there for 36 hours – quick release of estrogen – quick reversal of inhibitory effect and it stimulates release of LH – this stimulation occurs on apprx. Day 11-13 of the woman's cycle - the stimulation of the burst of LH begins approximately 36 hours prior to ovulation - It will peak approx. 16 hours prior to ovulation.
      
    • The surge in LH increases the secretion of steroidal hormones by the graafian follicle- The graafian follicle is the un-ovulated follicle starts to produce steroid hormone (progesterone)  - Progesterone levels start to rise - This is called luteinzation of the follicle - The progesterone level will rise then have a spike - The spike does two things causes temperature spike and causes burst of release of FSH - The only effect of the spike of FSH is to inhibit or turning off FSH - The spike in LH will induce the oocyte to complete meiosis I and to enter into meiosis II - Oocyte was frozen in prophase of meiosis I but not frozen in metaphase meiosis II - It remain in metaphase II until fertilization.
      

  Ovulation
  

  • The LH and the FSH combine to cause swelling of the tertiary follicle a few days prior to ovulation - The original production of the tertiary follicle was strictly due to FSH, no LH receptors - When It began in follicular phase LH started to appear on the granulose cells and increase in number all through that phase - Now the FSH is shut down and LH takes over - FSH and LH act together to get to ovulation but the pressure in the follicle stays about the same about 15-20 mmHG
    
  • The spike in LH causes the theca externa of the graafian follicle to release collagenase which weakens the capsular walls which allows more swelling which allows new blood vessel to grow into the follicular wall - The follicle secretes vasodilators which increase the transudation and increase the swelling of the follicle - Just prior to ovulation a protrusion appears in the outer wall of the follicle. This is called stigma - The stigma will exist about 30 minutes. After about 30 minutes the stigma starts to leak fluid - Thus the follicle is shrinking and dropping in pressure - what causes the explosion of ovulation are the specialized cells of the theca externa (smooth muscle cells) - they are stretched around as the follicle as got bigger, when it shrinks the start to contract - Once they contract for about 2 minutes there is a giant contraction –this is what causes ovulation
    
  • The oocyte is released in to the abdominal cavity - The oocyte is still surrounded by the zona pellcuiea. It is also surrounded by the corona radiadae (first layer of granulosa cells outside the zona pellcuiea) and the cumulus oophorus -The remainder of the follicle is left in the ovary - The remainder left there becomes the corpus luteum - The CL produces progesterone, estrogens, and relaxin - As LH levels drop the CL becomes non functional - It becomes non functional approx 4 days prior to the start of the menstrual cycle - The degradation of the CL is possibly due to a oxidosen reaction of prostaglandins
    
  • If fertilization occurs HCG (human chorionic gonadotroin) is secreted by the chorion and binds to the same receptors as the LH - So when the LH drops the receptors still stay stimulated and the CL stays functional - The chorian eventually become the placenta. HCG is the first placenta hormone. HC somatomamotropin works on estrogen and progesterone to promote breast development/growth - HCT HC thyrotroin increase the maternal metabolism - Relaxin has several roles - Inhibit myometrial contractions - Also relaxes pubis synthesis and other pelvic joints. In preparation for child birth. It relaxes the cervix -The last two hormones from the placenta are estrogen and progesterone.
    

  Fertilization
  

  • When the sperm comes in contact with the cumulus oophorus it releases hyaluronidase which dissolves the cumulus oophorus - Sperm goes to the zona of the oocte and loosely  attaches to ZP-2 glycoprotein  (weak bond) Then it will bond to the ZP-3 glycoprotein (species specific) - The sperm then undergoes the acrasomal rxn - The sperm head binds to the carbohydrate of the glycoprotein and the protein cause the acrasomal rxn
    
    • Acrasomal rxn - is when the sperm releases digestive enzymes, which eat through the zona. Then it enters the perivitelline space (the space between the oocyte and the zona) - It goes through that space and comes in contact with the plasma membrane of the oocyte. Binds with fertilin and cryitestin, binds then to: Izumo from the sperm head fuses at this point. This point is called fertilization (when fusion occurs)
      
  • The head of the sperm will release NO, which opens calcium channels which causes calcium waves across the oocyte - the calcium stimulates the oocyte to finish meiosis II -The polar body disintegrates - Following the calcium wave will occur for the next few hours lasting only a few minutes - the calcium spurts cause cortical granules - the granules release their contents into the perivitelline space - This causes two effects
    
    • Water is dragged out into the perivitelline space- This increases the size of the perivitelline space preventing more sperm to enter - Shrinks the sona pulling the plasma membrane away from the zona
      
    • The second effect changes the shape of the ZP-3 and the digestive enzymes stop being effective. Even though the sperm can still bond to the ZP-2 it cannot bond the ZP-3. This is called a block to poly sperm. 
      
  • The tail is always destroyed weather it breaks off outside or dissolves inside (also includes the mitochondria.) Every mitochondria in your body came from your mother - The nuclear envelope is dissolved and a pronucleus is made - The only thing that survives are the chromatin material and the centrioles - The DNA then replicates - The centrioles from the parents form a spindle - The envelopes come up from each side and mitosis is completed. - 2 daughter cells with same nucleus are made. 30 hours have passed since fertilization has occurred.
    

   
   

  Pregnancy
  

  • Chance of pregnancy – based on normal men and women
    
    • 7 days prior = 0%
      
    • 6 days prior to ovulation 0% people got pregnant
      
    • 5 days prior to ovulation 8% got pregnant 
      
    • 2 days prior 36% got pregnant and stays there till the day of ovulation
      
    • Thru 1, thru day of ovulation = same
      
    • The day after ovulation it drops to 0% immediately.
      
  • Spike shows how the sperm can live up to 5 days in the isthmus of the fallopian tube
    
  • The oocyte has short viability - that's what the flat part/drop off represent
    
  • Types of Labor
    
    • Rule #1 = there are no rules
      
    • Rule #2 = number 1 never change
      
    • Braxton Hicks contractions - First described by John Braxton Hicks - Coming from the mother - Caused by estrogen produced which increase the number of oxytocin receptors in the mitometrium and the dissidua(part of placenta) - To the point where the receptors are 100-fold more than during early point in gestation - When there were very few receptors there are no contractions (in the early months)
      
      • Used to be called false labor, but that's a misnomer
        
    • True labor - Coming from the baby (baby saying I'm ready to be born) - When the baby is ready to leave, it gives a rise in fetal oxytocin which stimulates the dissidua oxytocin receptors - Receptors release prostaglandins which stimulate myometrial contractions - Cervix is separate organ from the uterus - Uterus contracts – cervix expanding - As cervix dilates stretch receptors send back neural signals to the hypothalamus which increases the oxytocin which increases the contractions of the uterus and dilation of the cervix (positive feedback system, continues until baby is released)
      
    • As baby moves into vagins, stretch reflexes in walls of vagina reflexively activate abdominal muscle contractions at the same time as uterine contractions
      
    • At same time, mother gets urge to contract abdominal muscles too. Called pushing - this aids in delivery of baby, although most places say to fight the urge to push until cervix is dilated 10cm - once mother starts, its virtually impossible to stop
      
    • After baby is born series of contractions continue until placenta is delivered