Transcribed by Erica Manion 5.5.14Organ Systems Lecture 49

Histology of the reproductive System by Dr. Lopez

[Slide 1] Histology of the Reproductive SystemDr. Lopez: OK is everyone ready? We only have an hour to go through male reproductive histology and female, so this is going to be really rushed I think, well see how it goes. Anything we dont cover we can cover in the integration lecture.

[Slide 2] Reading AssignmentsJust to make sure you really get everything, here are the chapters you should read because we wont have time to go into too much detail today.

[Slide 3] Male Reproductive SystemSo for the first half we are going to talk about the male reproductive system. So just kind of an overview of the anatomy. You should remember it from the pelvis unit in the fall. So this is sort of a mid sagittal section, its not perfect. Its mid sagittal through the penis, so you can see the urethra here in purple, and then the bladder as well. So heres your bladder, prostate, and here is the urethra coming from the bladder going through the prostate to the penis. Everything else is bilateral. So even though its shown in this diagram, it really shouldnt be in the midline. You have your testes in the scrotum with the epididymis behind the testes. Vas deferens (or ductus deferens) going up here, so from the scrotum through the body wall. Seminal vesicle behind the bladder, bulbourethral gland is back here. So make sure you review the anatomy yourself.

[Slide 4] Development of the Male Reproductive SystemA brief discussion of development. In the embryo, the male embryos and female embryos develop the same at first, and then differentiate later. So here is the ventral side of the embryo. This is the gut tube, the mesonephros here, and thats going to be involved in renal development. We are cutting transversely across the embryo, thats what this picture is (referring to picture B, top part of slide). You have the aorta with blood vessels, this is the mesenephros right here. Medial and ventral to that you have a bulge I guess called the genital ridge. Thats going to develop into gonads in both sexes. So this is another picture of it (referring to picture B, lower part of slide). So heres the mesonephros, and then in red is the genital ridge. The genital ridge will develop into the gonads, which will contain sperm or eggs eventually. The cells that will develop into those sperm and eggs are germ cells. They migrate into the embryo from the yolk sac. So they start in the yolk sac, migrate into these genital ridges to eventually be more mature germ cells, the sperm or the eggs. Related to the genital ridges you have duct systems. In both sexes, again you have the mesonephric duct, also called the Wolffian duct, and the paramesonephric duct, which is called the Mullerian duct.

[Slide 5] Development of the Male Reproductive System, images of 4 week and 6 week indifferent gonadsSo this is very early on in development. Its just the same cross section I just showed you. You have the mesonephric ridge with a genital ridge medial and ventral to it. In the mesonephric ridge you have the mesonephric tubule, or the mesonephric duct (indicating green structure). This is all involved in kidney development. And here, this little arrow (in top image) is showing germ cells coming from the yolk sac to invade the genital ridge. This is happening in males and females.

[Slide 6] Development of the Male Reproductive System, images of 8 week and 16 week testis development.In males, this genital ridge will develop into the testes, and you can see here, the mesonephric tubule is going to persist (indicates green structure in top image, then green structure in lower picture). So here is your mesonephric tubule or Wolffian duct. Next to it you have a Mullerian duct.

[Slide 7] Nature Reviews imageIn male embryos, if everything develops correctly, the Wolffian duct, or the mesonephric duct, same thing, persists and develops into adult male structures like the epididymis, the vas deferens and the seminal vesicle, and the Mullerian ducts will disappear. The opposite will happen if you are a female embryo. You dont have to know too much about development, but know that male and female embryos are developed identically at first but then they differentiate a little bit later, and know which duct persists in which sex.

[Slide 8] TestisSo now lets move on to the histology. So first we are going to talk about the testis. In adult men they are located in the scrotum outside of the body wall. They produce sperm and testosterone. If you look inside a testis, youll see lots of microscopic tubules, the seminiferous tubules, arranged in lobes or lobules. The entire testis is surrounded by a dense irregular connective tissue capsule called the tunica albuginea. The capsule is going to sends septa deep into the testis, which is going to create these lobes.

[Slide 9] Testis, histology imagesSo here is a slide of that. So this is pretty much a section through an entire testis (referring to image on the left). Each of these little purple squiggles that you see is a seminiferous tubule. This is the capsule that surrounds it, so this is the tunica albuginea. I cant really see septa coming down from it at this magnification, but the seminiferous tubules are in these lobules.This is a higher magnification (referring to image on the right). You can see the capsule here. So this is the tunica albuginea, its dense connective tissue. Here its going to go deeper into the testis to create a septum dividing the seminiferous tubules into lobes or lobules. At this magnification, you can see the tubules are hollow tubes, so here would be the outline of the seminiferous tubule cut in cross section (referring to the structures labeled Seminiferous tubules on the lower right part of the image). Here would be one, and here would be one here.The midline of each testis is called the mediastinum testis. So just like you have a mediastinum in your chest, the testis does as well.

[Slide 10] Testis + Intratesticular Genital DuctsFirst, lets talk about the seminiferous tubules. There are multiple seminiferous tubules in each testis. They are very long, convoluted, hollow tubes where sperm development takes place.

[Slide 11] Seminiferous tubulesSooo its not showing us a cross section here. This is a very magnified picture. So imagine that this (indicating Basal Lamina) is the base or the outside of the tube, its going to continue around in a giant circle that goes off the screen. So down here is the outside of the tubule (indicating area containing fibroblasts, below the area labeled Basal Lamina) and this would be the lumen of the tubule (white area above the structures labeled Late Spermatids). So a giant circle that is too large to fit on the screen. Around the outside of the tubule we have a layer of connective tissue, blood vessels, and interstitial cells. This will be the basal lamina surrounding the tubule, because its epithelium so it will have a basal lamina. The epithelium itself is very unique. Its stratified but you will have columnar cells as well. The stratified cells here (indicating green, purple, and white cells) are the spermatogenic cells, the cells that actually develop into sperm. And the very tall cells, the sertoli cells, they are there to support the spermatogenic cells.

[Slide 12] SpermatogenesisSo on this slide, MAKE SURE YOU REALIZE THERE WAS A PRETTY BIG TYPO HERE. To create spermatozoa we are using meiosis, NOT mitosis.

So the cells in the previous picture, the spermatogenic cells, undergo meiosis to give us spermatozoa. So this process of sperm development is called spermatogenesis. In males, spermatogenesis begins at puberty, so its not happening before puberty, and continues for almost your entire life. From the outside of the tubule, so here, this is the outside of the tubule, (orange area labeled in picture as Tubule Wall), this is the lumen (to the right of the immature sperm), we have a population of spermatogonia, these are diploid cells. And they divide via mitosis, so its giving you another diploid cell. That mitosis renews the stem cell, the spermatogonia population.. The mitotic divisions here will also gives us primary spermatocytes. These are also diploid cells. These cells begin meiosis. They undergo meiosis one to go from primary spermatocytes to secondary spermatocytes. And those undergo meiosis II to give us spermatids. And the spermatids are still going to be round cells, they arent going to look like sperm yet. So we go from spermatogonia, which are diploid, to primary spermatocytes, still diploid, secondary spermatocytes, then spermatids.

[Slide 13] - SpermiogenesisThe spermatids will mature into spermatozoa, and this process is called spermiogenesis. So the entire process, going from the original diploid cells to spermatozoa, is spermatogenesis, and the maturation of spermatids into sperm is spermiogenesis. So similar words, but they mean slightly different things. And that is going to be this maturation from this round looking cell to a typical sperm, where the nucleus forms the head of the sperm. You get a middle piece with lots of mitochondria, and this very long tail. So the middle piece and the tail are moving the sperm towards the egg.[Slide 14] Path of spermSo the sperm are all made in the seminiferous tubules. From there, they have to get out of the body. So they go from the seminiferous tubules, and these are all very convoluted, to straight tubes, or tubuli recti, which then go into the rete testis, which is here, a network of tubes in the mediastinum. From there they go through efferent ductules to get to the epididymis. The epididymis is one long tubule that is continuous with the ductus deferens. From there it goes to the ejaculatory duct, and then the urethra, and the outside world. And well look at each of these but this is just a pathway of how the sperm gets out.

[Slide 15] Seminiferous tubulesSo heres a slide of two seminiferous tubules. This is the outside of one, with the lumen down here (white area at bottom of image), and this is the outside of the other, and the lumen would be up here (see image below). So you can see the spermatogonia would be towards the base of the tube, and the spermatocytes are more toward the lumen of the tube. Here theyd be higher up. Heres a spermatogonium, and spermatocytes down here. A sertoli cell (SC) is supporting the spermatogenic cells. You can tell the difference between a sertoli cell and the spermatogenic cell because the sertoli cell has a very oval shaped, pale nucleus. And then, when you see these skinnier nuclei, those are spermatozoa (Sz). So development is going from the outside of the tube towards the lumen.

[Slide 16] Sertoli cellsSertoli cells are not dividing to create spermatozoa, they are nurse cells to support those spermatogenic cells. They provide nutritional support, they clean up any debris left over from spermiogenesis, they produce anti-Mullerian hormone, which is involved in getting rid of the Mullerian duct in fetal development, and they also have tight junctions between them to create a blood-testis barrier which will protect the developing spermatogenic cells. So in the lower picture here, the giant cells in pink are sertoli cells. So there is one sertoli cell here, and one sertoli cell here, and they have projections so that they touch. At the base, there are going to be tight junctions to separate anything in the blood down at the outside of the tube from affecting the environment of these spermatogenic cells. So they create a blood-testis barrier. And you can see how much in contact the sertoli cells are with the spermatogenic cells, so they are really there as support or nurse cells.

[Slide 17] Tunica propriaSo on the outside of the seminiferous tubules you have the tunica propria. It is a layer of interstitial cells. You have myoid cells directly below the basal lamina and interstitial cells outside the tubes. The interstitial cells are also called Leydig cells.

[Slide 18] Interstitial cells or Leydig cellsLeydig cells are involved in producing testosterone. Testosterone is needed for proper sperm development but the seminiferous tubules dont create this testosterone themselves, the leydig cells outside the seminiferous tubules do that. So here is a seminiferous tubule here (indicating image on left). So inside will be the spermatogenic cells and sertoli cells, while the leydig cells creating the testosterone will be outside the tubes.

[Slide 19] Testis +Intratesticular Genital DuctsAfter we leave the seminiferous tubules, spermatozoa pass into the tubuli recti, which are the straight part of the seminiferous tubules not shown on this diagram, and then into a network of tubules called the rete testis. That is going to lead you from the seminiferous tubules into the efferent ductules here.

[Slide 20] Rete testisThe rete testes are just a network of tubules. Theyre in the mediastinum testis, so in the midline of the testis.

[Slide 21] Testis +Intratesticular Genital DuctsNext up are the efferent ductules or the ductus efferentes. For most of these youll see Latin names and English names, you can use either one. And these connect to the epididymis.

[Slide 22] Ductus efferentesHere you have two different kinds of cells. You have non-ciliated and ciliated cells which give the efferent ductules a scalloped appearance in cross section. So here is one efferent ductile in cross section and you can see there is an alternating pattern of ciliated and non-ciliated cells that give it this undulating outline. The cilia will help move the sperm towards the epididymis. The sperm arent mature yet, so theyre not swimming anywhere. Theyre just moving because of the cilia.

[Slide 23] Extratesticular DuctsSo next up, we have a series of ducts outside the testes. So first the epididymis. Its one very long, skinny convoluted tubule. Then the ductus deferens, which is also called the vas deferens, and then the ejaculatory duct to get into the urethra.

[Slide 24] EpididymisSo first the epididymis. Its behind the testis. It has a head, a body, and a tail, heres the tail. The tail is continuous with the ductus deferens.

[Slide 25] EpididymisThis is where sperm hang out for a long period of time. Its for sperm storage and sperm maturation. Heres a more realistic picture. So head, body, and tail, and the tail is continuous with the ductus deferens.

[Slide 26] EpididymisIt has epithelium with stereocilia, so its one of the few places in the body that you see stereocilia. We can see two cross sections through the epididymis here, so heres one and then the one at the bottom. In the lumen you see lots of sperm cells, spermatozoa. Around the base of the tubule youll see basal cells (BC), so, short, round, or pyramidal shaped cells. These are going to be stem cells that can act as a reserve for principle cells (PC). Principle cells are tall and have oval shaped nuclei, so all of these are principle cells. They absorb any excess fluid with their stereocilia and they produce a glycoprotein that inhibits capacitation. So thats the final step in sperm maturation. While the sperm is in the epididymis it will mature, but it doesnt fully mature. It doesnt undergo capacitation until its in the female reproductive tract.

[Slide 27] EpididymisHeres another picture of the epididymis that I put on because I really like it, I like the long stereocilia, I think its pretty. So I gave you an extra picture of that.

[Slide 28] Ductus deferensNext up is the ductus deferens. The unique thing histologically about this is how thick the muscular wall is.

[Slide 29] Ductus deferensSo if you look at this, heres the outer edge of the ductus deferens, and heres the lumen. The wall is extremely thick with three layers of muscle that alternate longitudinal, circumferential, and then longitudinal again. So heres one layer, heres another layer, and heres the third layer. And then it has a pseudostratified epithelium, ciliated, along the lumen. And in this more magnified picture you can see that there is some cilia there, but definitely pseudostratified.

[Slide 30] Ejaculatory ductThe ductus deferens goes in through the body wall, goes behid the bladder, hooks over the ureter, and is going to have a shared duct with the seminal vesicles which we will look at in a minute. That duct is called the ejaculatory duct, so there will be an ejaculatory duct on either side that will empty into the prostatic urethra. So heres your bladder, seminal vesicles in the back, prostate is inferior to the bladder, and here are the ejaculatory ducts emptying into the urethra. It is a simple columnar epithelium, and there is no smooth muscle unlike in the ductus deferens.

[Slide 31] Accessory Genital GlandsSo while we are back here lets look at the glands. We have three glands that will form the fluid part of semen. The testes form the cellular part, the spermatozoa. So we have seminal vesicles, one on either side, A single prostate gland, and two bulbourethral glands.

[Slide 32] Seminal vesiclesThe seminal vesicles are producing the majority of the semen, and its going to be very rich in fructose which will provide energy for the spermatozoa. Its actually just one lumen, but the wall of the gland is so folded and convoluted, that you might be confused into thinking that its lots of tubules, but if you expanded this thing it would be just one lumen thats very folded up. It has pseudostratified epithelium surrounded by smooth muscle. So this is a magnification (image on right). You can see smooth muscle cells here (SM), but this isnt really showing you how folded it is, but this picture is good at that (image on left).

[Slide 33] Prostate glandThe prostate gland also produces a fluid that is in semen, including some enzymes and citric acid. It has multiple glands arranged in layers. So this diagram is showing the urethra is in the center of the prostate and there are glands in three layers around it. And the glands are lined by either simple up to pseudostratified columnar epithelium. Just like in some other parts of the body, with age you might get concretions or calcifications and thats what is shown here (indicating pink spot in top right image). So here is a clacification, and it is magnified right here (lower image)

[Slide 34] Bulbourethral gland (Cowpers gland)The Bulbourethral gland, a.k.a. Cowpers gland also produces fluid thats part of semen. Its epithelium is simple cuboidal to simple columnar. So this part looks pretty cuboidal, while this part looks more columnar.

[Slide 35] Histophysiology of Accessory Genital GlandsOk, you can read that on your own because we are running out of time for the male.

[Slide 36] PenisIf you look at the penis in cross section you can see that it is made of three erectile pieces or columns. So you have two corpus cavernosum up here, and one corpus spongiosum. The corpus spongiosum is where youll find the penile urethra, or spongy urethra. Same thing. In cross section it kind of looks like a face. So the two corpus cavernosum are on top and the corpus spongiosum is below. Each of these are made of erectile tissue, so youll see lots of spaces here where it can fill with blood.

[Slide 37] Female Reproductive SystemOk, now we are onto the female reproductive system. So again, a quick overview of the anatomy. We have the uterus here. Below the uterus we have the vagina. The cervix is the part of the uterus that projects downwards into the vagina. Then either side of the uterus you have uterine tubes, they are also called fallopian tubes or oviducts. The ends of the uterine tubes have these fimbriae sticking out. And next to it but not connected youll have the ovaries. So there is a physical space between the ovaries and the uterine tubes, they are not fused together in any way. The ovaries are showing different stages of oocyte formation. The ovaries are attached to the uterus via the ovarian ligaments. I dont have a picture of the external genitalia but Im sure its in your book.

[Slide 38] Development of the female reproductive systemSo just like with male development, females start out with the mesonephric ridge, with the genital ridge right next to it. The Wolffian or mesonephric duct (pointed out the structures on the top figure, 4 weeks). The germ cells migrate into this genital ridge from the yolk sac but here (bottom figure, 6 weeks), this is going to develop into the ovaries, not the testes.

[Slide 39] Development of the female reproductive systemSo if you go back to the similar slide showing male development, it will show multiple cords here (bottom figure, 20 weeks), or tubules, in the developing testis. Here, you dont have developing cords so much, you have more connective tissue, vascular medulla of the ovary, and well see that histologically in a second. You still have the Wolffian duct and Mullerian duct, the mesonephric duct and paramesonephric ducts. However, now... (next slide)

[Slide 40] Nature Review figurethe Mullerian ducts stay and the Wolffian ducts degenerate. So in the female, the Mullerian ducts form the fallopian tubes, uterus, cervix, and vagina. If you look here, you have one Mullerian duct on either side, so you keep bilateral uterine tubes from the Mullerian duct, but hopefully everything fuses together in the midline, so you get one uterus, one cervix, one vagina. Sometimes that doesnt happen and you end up with two. Remember the Mullerian ducts continue in females and the Wolffian ducts degenerate, and the opposite happens in male development.Oh one thing to note: Since the gonads in males and females develop identically at first, that means they are both developing in the abdomen. In males, the testes are pulled down into the scrotum, and in the females the ovaries are pulled down a little bit to get near the uterus, but are not pulled down all the way to the labia the way they would be if the embryo was developing into a male. So they both start off in the abdomen and descend to the appropriate level depending on whether the embryo is a male or a female.

[Slide 41] OvarySo here is an ovary, you have a cortex and a medulla. The cortex is obviously on the outside, and the medulla is deep to that. The cortex is where egg development occurs, thats what is being shown here. The medulla is where you find blood vessels and connective tissue.

[Slide 42] OvaryHere it is histologically. This corner (bottom left) is the medulla and the rest of it is the cortex. When you see these little cells (along outer cortex boarder), these are earlier stages of oocyte development or follicular development. The larger follicles you see here are later stages, so these are more mature (labeled Ovarian Follicles).

[Slide 43] Ovarian MedullaA larger picture. So here is the medulla with the cortex around it. The medulla has a lot of connective tissue, interstitial cells, hilus cells which are similar to the leydig cells of the testis, they secrete androgens. And we have interstitial cells that secrete estrogens. And the blood vessels here are branches of the ovarian arteries.

[Slide 44] Ovarian CortexThe cortex is where the oocyte development takes place. This is a schematic version showing early development of the egg, and then later development, this is ovulation, and this is what it looks like after ovulation.

[Slide 45] Oocyte developmentSo, lets talk about the different stages of egg development. We dont have tubules the way we did in the testes. This is all happening in the cortex. And unlike sperm development which happens continuously from puberty to basically the end of your life, egg development starts during fetal life, so a female fetus, pauses until you start puberty, then restarts again. But only one or two eggs a month will ultimately be ovulated. So most of the eggs are in what is called a primordial follicle. So you have an oocyte surrounded by follicular cells, basically looking like this.

Oh, before I go into egg development lets talk about whats on the screen. This is the outside of the ovary. The outside is not covered with a very thick capsule. You have a simple cuboidal epithelium, called a germinal epithelium. Dont get confused by the word germinal. Germ cells mean sperm or eggs. These are not involved in that at all, just the covering of the ovary. And you also have a thin tunica albuginea. Underneath that is where the egg development is occurring.

[Slide 46] Primordial follicleSo, starting off with the primordial follicle. You have oocytes, so the very large cells with the large nuclei, surrounded by a single layer of squamous follicular cells. Thats where most of your oocytes are occurring as primordial follicles.

[Slide 47] Primordial follicleThen, as they develop, primordial follicles will develop into primary follicles. The follicular cells surrounding it will become more cuboidal, so here (indicating cells lining the lowest lumen in the left image), these are cuboidal now, and increase in number. So they go from simple cuboidal to stratified. And AT THE TOP IT SHOULD SAY PRIMARY FOLLICLESo this would be a primary follicle that is unilaminar, because it has one layer of follicular cells, and this would be a primary follicle that is multilaminar because it has multiple layers, its stratified. These follicular cells, the ones surrounding the oocyte, are called granulosa cells, and then around those granulosa cells are theca cells. If they are close to the granulosa cells, they are called theca interna, if they are far away you would call them theca externa.

[Slide 48] Secondary or antral follicle, Graafian or mature follicleThen a primary follicle will mature into a secondary follicle, thats also called an antral follicle. That occurs when these granulosa cells get hollow areas in between them. So here would be a hollowness or a space between the granulosa cells (light pink areas in left image labeled with an A). Here is another one, and here is your oocyte (labeled O) inside the granulosa cells. The spaces, the hollow spaces are called antrums. So here would be an antrum, here would be an antrum (again, pointing out the areas in the left image labeled A). When those multiple spaces get large enough that they are one big single antrum, then you would call it a Graafian or a mature follicle. This is almost ready to be ovulated (indicating the right image). The oocyte isnt just floating in the antrum, its connected to the rest of the granulosa cells on this stalk, and is still surrounded by many layers of granulosa cells. And these layers surrounding it are called the corona radiata.

[Slide 49] TableThis is just a table summarizing the different stages in follicular development. Basically at any given time you have multiple primordial and primary follicles and secondary follicles, but only a couple eggs, or oocytes, each month are going to reach the mature Graafian follicle stage and be ovulated. Usually one, maybe sometimes two. The rest of them will just degenerate. So you have multiple oocytes maturing each month, but most of them dont get to the ovulation stage, and just become resorbed by the body.

[Slide 50] Oocyte ovulationSo, after a follicle reaches the Graafian stage, it can be ovulated. For ovulation you need a surge of LH, luteinizing hormone, released from the anterior pituitary. Until this point, all of the oocytes, starting from when this ovary was inside a fetus, all of the oocytes were stalled during meiosis I. At ovulation, the ovulated oocyte will finish meiosis I and stall at meiosis II, and will only finish meiosis II if it is fertilized.So this is ovulation, basically the follicle bursts through the wall of the ovary and the oocyte is expelled from the ovary along with the follicular cells that are still attached. So now this empty follicle will collapse on itself and becomes the corpus luteum. Meanwhile, the oocyte goes into the fallopian tubes, makes its way down the tubes, may or may not be fertilized, and if it is fertilized, may or may not be implanted in the wall of the uterus.

[Slide 51] Corpus luteumLets look at the corpus luteum. So that is basically the collapsed, empty follicle. It produces hormones that support the uterine endometrium in case there is fertilization and implantation. The granulosa cells, the cells that were right around the oocyte, are now called the granulosa lutein cells, they are here (labeled GL). They are going to secrete progesterone and estrogen. The theca lutein cells which were around the granulosa cells in the follicle, will secrete progesterone and androgens.

[Slide 52] Corpus luteumSo in this picture, this is a less magnified version, the pale cells are the granulosa lutein cells (of top image), so here are the granulosa lutein cells (lighter pink layer labeled GL) are large and pale, and produce progesterone and estrogen. They are more on the inside of the corpus luteum because they were more interior in the follicle.The theca lutein cells here are smaller and darker, and because they ere on the periphery of the follicle they are also on the periphery of the corpus luteum (labeled T in the more magnified image). They produce progesterone and androgens. So all of those hormones are there to support a possible pregnancy.

[Slide 53] in the absence of fertilization and implantation, the corpus luteum degenerates into corpus albicans in 10-12 daysIf there isnt a pregnancy, then the corpus luteum gets smaller and is eventually called the corpus albicans (albicans because it is white). This is a summary of the entire cycle (top image). So the oocyte that will be ovulated starts off as primary, secondary, Graafian is ovulated. The follicle turns into the corpus luteum, and if there is no pregnancy, it will get smaller and regress and become the corpus albicans.This is showing the levels of FSH and LH. You need this LH surge from the pituitary to induce ovulation (second image).And these are the hormones produced by the ovary itself, so estrogen and progesterone (third image). These should all be covered in the physiology lectures that come up next.If implantation and pregnancy does occur, the corpus luteum stays around for three months instead of degenerating.

[Slide 54] Oviducts / Fallopian tubesOk, lets go from ovary to uterine tube. After the egg is ovulated, hopefully makes its way to the uterine tube. That usually happens, but since these arent fused together, it is possible for it to slip out and go into the abdominal cavity. There are several names for the different locations along the uterine tube. So, the fimbriae are these finger-like projections at the end. The wide area here is called the infundibulum, and then the ampulla. The narrow area of the tube as it is going into the uterus is called the isthmus. And then you can see the tube goes through the wall of the uterus, so this is called the intramural portion, and then you are at the uterus.

[Slide 55] OviductHere is a cross section through the uterine tube. You have a serosa on the outside. Remember that is simple squamous epithelium. Then you have a muscular layer and a mucosa. The mucosa is folded, so there is a large surface area here.

[Slide 56] OviductThe mucosa is simple columnar, and it changes depending on where you are in the uterine tube. You have two types of cells, you have 1. ciliated cells. The cilia are there for movement, to move the oocyte towards the uterus, and you have 2. non-ciliated cells called peg cells. They secrete fluid to support the egg and the sperm, and help with sperm capacitation, which is the final maturation step of the spermatozoa that is necessary before it can fertilize an oocyte.So I dont think this pic is large enough for you to see the details of the peg cells versus the ciliated cells, but go to your book and look it up.

[Slide 57] OviductHere we go. Never mind. So, we have a magnified view so you can see the cilia here, so these are the ciliated cells (labeled CC). These are the peg cells that stick up and you can see that they dont have cilia (black arrow heads). So once you see a larger version it is pretty easy to tell the difference.

[Slide 58] UterusNow we get to the uterus. It has a very thick, muscular wall. The muscular wall is called the myometrium and the mucosa is called the endometrium. Here is the cervix, the most inferior part of the uterus.

[Slide 59] EndometriumThe endometrium is the mucosa, so it will have an epithelial layer here with glands going down and many blood vessels. There are two layers of the endometrium. One is the functional layer, or the functionalis. And one is called the basal layer or the basalis.The functionalis is very thick, and that is what comes off when you menstruate, and then regrows every month, and then is sloughed off again when you menstruate the next month. But you can see the functionallis has all these glands and blood vessels. So, after it is sloughed off, the glands and vessels have to regenerate and that is why menstuation is associated with blood because all of these blood vessels dying and being sloughed off, so there is bleeding involved. The epithelium itself is simple columnar. You still have non-ciliated and ciliated cells the way you did in the uterine tubes. Underneath the epithelium you have this lamina propria layer with glands. Below the basal layer, you have the myometrium, which has the arteries from which the coiled arteries originate. So let me explain this one more time. You have arteries in the myometrium, straight arteries going from the myometrial layer through the basal layer of the endometrium, and these coiled arteries going to the functional layer of the endometrium.

[Slide 60] EndometriumHere is the muscular layer of the uterus, the myometrium. And then above it you have the endometrium. You can see these glands here, thats how you know its the endometrium (labeled GL of right image). Magnified you can see the epithelium on the surface f the endometrium going down into glands. This is all lamina propria, here is another gland (bottom right of left image, labeled GL).

[Slide 61] Menstrual CycleThere are three phases of the menstrual cycle. The first phase, so when you say Day 1 of someones cycle, thats going to be the menstrual phase, so the beginning of the menstrual period is day 1. So youre at the menstrual phase, thats when the functional layer is sloughed off. Then you have the proliferative phase. That is when it regrows. Then the secretory phase is the maintenance of the endometrium in case a fertilized egg implants.

[Slide 62] UterusSo here it is histologically, first the menstrual phase here, lets start proliferative. In this phase, the functionalis layer of the endometrium grows, glands and blood vessels have to regenerate after menstruation. And you can see glands here but they are all pretty straight, not too convoluted (Left image, proliferative phase). After ovulation, (ovulation occurs between proliferative and secretory), you have the maintenance of the endometrium awaiting any fertilized egg. The arteries and glands become more coiled. So here all of these glands, you can see in the functional layer, are very curved and convoluted (middle image, secretory phase). And the cells secrete glycogen to nourish any implanted embryo.If pregnancy doesnt occur then you re-enter the menstrual phase. At this point the arteries running though the endometrium get narrower so oxygen is decreased and cut off from the functionalis layer. Basically necrosis occurs and the functionalis layer is sloughed off.

[Slide 63] MyometriumMyometrium has three layers, alternating longitudinal, circular, and longitudinal again, and during pregnancy both the size and the number of the cells increase. You need a thick muscle so during delivery it can squeeze the baby out

[Slide 64] CervixThe inferior part of the uterus is the cervix. It has glands, cervical glands, and youll see two different kinds of epithelium. Towards the uterus side youll see a simple columnar epithelium that secretes mucus, and towards the vagina youll see a stratified squamous non-keratinized epithelium. So that is the same kind of epithelium youll see in the vagina itself. I should get a picture of those because there is a discrete, immediate transition from the columnar to stratified squamous. Ill look that up and try get you a nice picture for the integration lecture, because that transition zone is where a lot of cervical cancer occurs. Whenever you see a transition in different types of epithelium, theres an increased probability that cancer will occur there.[Slide 65] VaginaFinally, the vagina is a muscular tube

[Slide 66] Vaginaand here, heres the muscular layer here, it is lined by stratified squamous non-keratinized epithelium and it doesnt have glands. So any glandular secretion is coming from the cervix, and is being dripped out by gravity.

[Slide 67] VaginaSo here is a picture of the epithelium. Again it is stratified squamous, but unlike your epidermis you dont see a keratinized layer. You can still see nuclei on the outer edge, so it is non-keratinized.

[Slide 68] Mammary GlandsMammary glands are glands that create milk.

[Slide 69] Mammary GlandsThey change from your non pregnant state to pregnant state to lactation state. Before pregnancy, you see a lot of connective tissue, very few glands. During pregnancy, the glands proliferate, and during lactation they proliferate and you see milk in the glands and the ducts.

[Slide 70] Mammary GlandsMilk is created using apocrine secretion. So you can see here the lipids and proteins are surrounded by this layer and its secreted by apocrine secretion. And Im finished right on time. Great. So, super fast because two lectures had to be combined into one hour, so let me know all the questions you have on the reproductive system.

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