hello everyone we're back again uh in the female reproductive system this is probably one of the last lecture mini lecture that you will be getting from me I was hoping that we would make it all the way through pregnancy and into delivery uh but from my calculations and I'm doing these recordings before the semester actually occurs we probably won't have enough time but I wanted to make sure that we at least got through conception and the beginning stages of pregnancy there are a lot of factors that are literally against the sperm cell and the OVA coming together and generating that new beginning this image that I have up here is one of my favorites showing you a humanova and a human sperm cell penetrating the wall of the OVA itself now again there are many many parameters here that have to be met so that we can actually have conception take place one of the first of these parameters I guess we could say is that sperm only has a short period of time where it actually has a better than chance level of of penetrating the OVA the wall of the OVA in fact as I have here sperm must be introduced within five days of ovulation five days before to one day after ovulation now this is a pretty specific parameter here why why are we stating this well sperm itself and we've mentioned about mentioned this before sperm are viable and can last probably four to six days inside of the female reproductive tissues before enzymes acid secretions other things start to tear and break every last one of those sperm cells down in fact we'll talk here in a little bit about how many sperm cells die in the process of just trying to get to the OVA but that's not necessarily the most rate limiting step here the actual egg itself is only viable 24 to 48 hours after ovulation that's a very short period of time that is a very very short period of time and as we talk about uh ovulation the movement the moving of that OVA from the ovary to over to the Fallopian tubes you're going to see for ovulate excuse me for conception to actually take place it's most likely going to have to happen in the fallopian tube let's continue here in this image a really beautiful image here showing you over to the right the uterus the uterine wall you can see the fallopian tube extending away from the uterus itself and you can see the ovarian ligament attached to the ovary way over here very small little spot that's the OVA the egg actually bursting out of the ovary being thrown out pushed out towards the fimbria of the fallopian tubes now these fimbria of the Fallopian tubes actually have smooth muscle cells within them and those smooth muscle cells of the fembria are literally pushing and moving those those finger-like projections to kind of surround and be as close to the ovary as it possibly can the actual cellular components or the tissue that sits on these fembria are epithelial cells that have cilia on top of them and those cilia have wave-like beading motions that are actually trying to move the OVA that has been released towards the opening here within the fallopian tube within the fallopian tube itself this is a major uh process folks if I were designing the body I probably would not have designed it in this way but the way it's designed there's a lot of peril in getting that small little OVA over towards and into the fallopian tube now this moving of the egg into the fallopian tube once that egg moves in there are cilia inside of the fallopian tube with their wave-like contractions helping to move the over over towards the uterus Plus because of particular hormone secretions like estrogen and progesterone you will have contractions peristaltic contractions of the fallopian tube trying to move that egg over towards the uterus the problem is all these motions are very very slow and because they are so slow it can take up to four days for the egg to actually travel the distance of the fallopian tube over to the uterus well if you remember from just the previous slide for that OVA to be fertilized it has to be fertilized within 24 hours to 48 hours after it's been released from the ovary that means if fertilization is going to take place it's got to take place here someplace within the Fallopian tubes and most likely here along the beginning parts of the fallopian tube now estrogen and progesterone are going to play a big role in this because they will cause contractions or those peristaltic wave-like emotions from the edge of the fembria towards the uterus and at the same time we'll set off contractions at the other end of the fallopian tube closest to the to the uterus wavelength contractions are moving in the other direction the reason hopefully sperm is catching the waves over here moving towards the actual OVA here in the fallopian tube lots of things have to be moving correctly folks I brought both of those both of these images back again because I love them so much for a sperm moving over towards the OVA ejaculation and the propulsion that comes from ejaculation is really probably the most important part for getting sperm from the vagina over to the cervix of the uterus now the surface of the uterus and the vagina itself has lots of materials lots of fluids lots of mucus associated with them and you may remember from previous lectures that mucus is slightly acidic it's trying to um take care of the tissues by breaking down bacteria and other other foreign substances sperm unfortunately gets caught up in this as well this is a really difficult process here the mucus if you remember also is very very thick and if you remember from a previous lecture lecture us talking about kilocrinons breaking down or being secreted and actually making some of the semen a little more fluid those killer crinons are also important in the uterus or I should say in the vagina and uterus helping to change the consistency of mucus so that sperm cells can swim a little more easily this this process is also being facilitated by estrogen as well okay so that mucus can be an impediment but with uh estrogen or excuse me that mucus can be a real problem from sperm cells but with estrogen being secreted it will help loosen up the mucus allowing sperm cells to be able to travel a little faster and a little farther along with other substances coming that are part of the semen itself well in this transport in this transport of of sperm cells trying to make it over to the Fallopian tubes or I should say through the uterus and up to the Fallopian tubes it is really dependent really dependent on the flagella of that sperm cell and all the energy that it may have associated with it and the contractions of the uterus and Fallopian tubes helping to move that sperm cell this is a long journey folks this is a very very long journey and because of this long journey the mortality rate of sperm cells is incredibly high again mainly because of the acidic environment of both the vagina and parts of the uterus as well so this is this is a big deal trying to get it to move as fast as it possibly can due to this length due to this journey if you remember we were probably putting out close to uh a few million sperm cells only a couple of hundreds of sperm cells will actually make it somewhere near the actual OVA for fertilization this is a huge attrition I guess you could say of of the sperm cells that have started this journey only a few will make it towards the end what's really pretty interesting though is that once they make it over to the Fallopian tubes special secretions from the cellular components that line the walls of the fallopian tube actually act to activate sperm cells kind of give them a second boost and energize I guess you could say the the surface of the sperm cell so that they're ready for penetrating the OVA this process is called capacitation that's the term down below capacitation I can only set it slowly to kind of make sure you understood it capacitation this capacitation is kind of an activating of these of these sperm cells well once those sperm cells have been activated we've got to get it into the actual OVA itself this image I have over to the right is the actual OVA in this kind of lightish brown color this is the actual cell membrane of The Yoga sitting just below it you can see what are called cortical granules these are going to be really important to us in a few moments folks these cortical granules above the actual cell membrane you will find this area in blue called the Zona pellucida the clear Zone above that or just outside of it you will see these cells and if you look up here at our image up to the upper middle here here's our OVA with what's left of the corona radiata or those granulosa cells remember those granulosa cells from inside of the ovary that are kind of traveling with the actual OVA these granulosa cells are still adding support to the actual logo and act as kind of a blocking mechanism for many sperm that are coming in you can see the actual sperm cells themselves once the sperm cells have been activated Remember by our by our process that we mentioned in the previous slide those sperm cells their job is to come in contact with the actual zone of palooza the Zona pellucida and the proteins associated with that act as a receptor for for proteins that are sitting on the surface of the actual acrosome of these sperm cells once they interact with each other that will help crack the top of the acrosome and allow the enzymes that are sitting within the acrosome to be released and start to eat away penetrating the zone of pellucidum and the membrane the cell membrane of the egg itself now I told you there were going to be some very important uh molecules that we're going to have to pay attention to one of those sets is the cortical granules that you see down below here once the acrosome breaks open and we get our acrisomal reaction enzymes Breaking Down the Walls one sperm cell will most likely beat all the others into the actual OVA once it enters the OVA once it enters the OVA it sets off a reaction a reaction with the cortical granules a reaction with the cortical granules those cortical granules those cortical granules will set off a defense a defense that's called the cortical reaction that cortical reaction these granules will will release enzymes that will start to inhibit and break down any other sperm cells that try to make it through the wall and try to make it through the wall of the actual OVA so here you can see the cortical reaction taking place over here this sperm cell has made it in these other cortical granules will start breaking down and prevent any other sperm cells from making it into the actual ovum this rupturing and releasing of these enzymes is important in trying to block what is called polyspermy polyspermy means having multiple sperm cells inside inside of the actual OVA that could cause some interesting problems all right we have one in the job is done the job is done we have fertilized the egg at this point let's go back and kind of review a little bit here so over to our left mini sperm bind to The receptors on the zone of pellucida and undergo the the acrosomal reaction of breaking down breaking down the Zona pellucida and the cell membrane sperm move through the zone of pellucida one sperm will bind to the egg plasma membrane and set off a reaction the egg releases contents of secretory vesicles these are our cortical granules enzymes enter the zone of pellucida and block any more sperm from entering sperm is drawn into the egg once that first one has moved egg completes its second mitotic division and now we have the development of a zygote all right and of course at the same time the egg is activating other enzymes that will promote the actual myogenic processes that are going to have this OVA start to replicate itself creating a blastosis how we're doing so far folks well if we let's move to the next stage here in this image we have our uterus we have our ovary we have our fallopian tube and as you can see we have ovulation taking place here we have the different stages after that ovulation of fertilization trying to take place the sperm cells coming trying to break through the zone of pellucida one of them being able to break through and now finally having the mitotic activity take place within the cell that will kind of Define this over now as a zygote meaning that it's starting to divide it is starting to create the new being that is actually been started by fertilization you can see here that this there are multiple stages of division that are going to take place and that this process happens immediately immediately so going from A two stage to eight stages takes a couple of days a couple of days for the most part to kind of occur and and get this process moving all the while the OVA is moving or I should say the zygote is moving through the fallopian tube now with peristaltic waves pushing it towards the uterus it will take remember from previous slides three four in some cases five days before that OVA can act or that zygote could actually make it over to the uterine wall over to the uterine wall now if everything's been going well estrogen has been secreted from the corpus luteum over in the ovary helping estrogen and progesterone I should say to help build up the tissue of the uterus ready and getting it ready for implantation of the actual zygote as it's moving the zygote as it's moving and moving into a stage where it has multiple divisions of cells we're going to be calling this the blastocyst and this blastocyst if we get up here about five to six days this ball of cells actually has multiple layers on the inside and we need to kind of look at that very very quickly in this image we have the blastocyst and now it is meeting up with the cells of the uterine lining of the uterine wall if you look inside of the blastocyst you'll see what's called an inner cell Mass an inner cell Mass this Inner Cell mass is what the actual child will develop from these are the cells that will create all the tissues that we have talked about all semester long but that could only happen if this blastocyst and the outer areas the triple blast can invaginate or embed itself within the uterine wall in this second image down below here you can see parts of the tropoblast have now invaded the tissues of the uterine wall this is a very important stage this invading tissue is called the chorion and chorionic villi these are invading into the tissues of the uterine wall this chorion and chorionic Dylan will develop into the placenta develop into the placenta it will help incorporate all the blood vessels within the wall of the uterine of the uterus the other cell tissues and bring all of that material in so that the Inner Cell mass will have nutrition for its development at the same time as these chorionic villi invaginate into the wall of the uterus they will all be working together to create another hormone the hormone HCG human chorionic gonadotropin human chorionic anatotropin this is released into the tissues and into the bloodstream mainly for the development of the chorion and the the creation of the placenta but this is a the hormone that we look for in determining do we have a pregnancy occurring HCG is what most pregnancy tests are testing for pretty cool now with all this let me just show you this graph here months after the beginning of the last Administration so we have over here the 30 days and of fluctuations associated with hormone secretions depending on whether we have fertilization or not taking place once fertilization has occurred and we have implantation you can see this Spike of human chorionic gonadotropin human chorionic gonadotropin which will signal yes that we have a viable pregnancy taking place you can also see how hormones secretions for estrogen and progesterone start to really take off at this point and you're hoping that that's going to occur because this is going to help uh push the development of the child of that inner Mass where is this estrogen and progesterone coming from it's probably not all coming from the ovaries remember back over here the ovaries and the corpus luteum are probably falling off by this point in time so where is this estrogen or progesterone coming from we'll talk about that here in a few moments in this last image that we're going to be looking at or last couple of images here we have the implantation of the OVA into the wall of the uterus and the area inside of that inner mass and inside of that OVA now is filling with an amniotic fluid that is going to be developing from what we will be calling the placenta now you can't see it very well in this image up on the top but here in this middle image you can see this strange imagination that's taking place here in the wall of the uterus if I zoom in on that so that we can look at that a little more closely this is what that looks like this is the development of the chorionic villi and the chorion and you can see how it will incorporate pulling in blood vessels pulling in the connective tissue and nerve tissue from all the area within the uterine wall that will come together and grow and move into this stock which will help Supply the developing fetus the developing fetus this will be the umbilical cord and all of this tissue over here to the left in this image is the developing placenta the developing placenta now that developing placenta is going to be important not just for the development of the child from this angle providing blood flow and all and and other tissue cells but also in producing the estrogen and progesterone that is going to be necessary for the development of the child in the womb in the uterus itself that was a long mini lecture folks but this is probably our last mini lecture for the semester I hope you've enjoyed them I hope that you've been able to gather information from all of this this was a long mini lecture go back over it's really fascinating and ask me questions in lab we'll talk to you later