so we have the sustentacular cells or sertoli cells they mediate the effects of testosterone follicle stimulating hormone nourish spermatocytes spermatids and spermatazzoa they phagocize excess spermatid cytoplasm control movements of the spermatogenic cells and release them into the Lumen ants Creek fluid for sperm transport as well as the hormone inhibit the light it cells are interstitial endocrinocytes are found in the spaces between the semifus tubules and they secrete testosterone so here you can see these are the sertali cells they kind of look like jigsaw puzzle pieces and in between them are these really large cells that get smaller and smaller and smaller until they become firm um up here is these it should say light egg not lighting I didn't make this somebody else good but these are the lighting cells and these are the ones that produce testosterone so here you can see this is a seminiferous tubule over here is a seminiferous tubule this is the the connective tissue in between and this is where you find the lighting cells they're in between the tubules okay all right so spermatogenesis is the process by which you produce haploid sperm we have diploids for matagonia we should say gonia um that undergo mitosis to reserve future stem cells and to develop cells for sperm production okay so we go from spermatogonium to primaries spermatocyte remember one of the guys is going to stick around the other one is going to become a spermatocyte and then we have our secondary spermatocyte spermatid and then sperm cell and here you can see this is the hollow interior here and as they get further and further down this purplishes the nuclei of the different cells you can see a nucleus gets smaller and smaller and smaller as these guys are being produced so um we have primaries for mattocytes endochromyosis one to form haploids secondaries spermatocytes and then meiosis II produces spermatitudes that are connected by cytoplasmic fridges the final stage these spermiogenesis which is maturation of spermatism sperm and then releases spermiation okay now we have 22 pairs of autosomes and one pair of sex chromosomes so the sex chromosomes are either X or Y and females have two x's men have an X and A Y now the X is not does not confer it doesn't have like a lot of things on it that make you female by default we are female it's only when the Y chromosome is turned on that maleness emerges okay there's an sry gene on the Y chromosome that's important for maleness so the default human is a female the male is um when the Y chromosome turns on then the same structures that would become say for instance the labia in the default model which is the female are they differentiate into the scrotum the same structure that would become the ovaries in the female become the test Deeds the same structure that would become the clitoris or clitoris in the female becomes the penis and so the Y chromosome is a little bitty guy confers maleness the X chromosome has a lot of stuff on it that has nothing to do with sex it has um genes on it for clotting factors and color vision and hair growth and all kinds of things and so if a man has a mutation on his X chromosome he has the disease a female would have to have an a mutation on both of her X chromosomes to have a disease and that's really rare okay so um for x-linked diseases females are carriers and men have the disease see very seldom see women who have hemophilia or women who are have red green color blindness or women who have male pattern baldness or women with defense muscular dystrophy those are almost all exclusively male diseases because they are mutated come from mutations on the X chromosome okay now this is what I meant by genetic recombination all right so if we said yellow is Mom and the red is Dad here we have two chromosomes um say chromosome one and two right um and now uh remember the chromosomes each half of the chromosome is what we call a sister chromatid and the other half is when it was duplicated when the DNA doubled this goes to one cell that goes to one cell this goes to one cell that goes to one cell so chromosome consists of two identical sister chromatids attached in the center by a centromere now these guys line up so these two are the same chromosome one to Mom one's from Dad these two are the same chromosome again once for Mom one's from Dad and they sit next to each other in the metaphase plate this is called synapsis where these guys find each other and sit next to each other they form what is called a tetrad Tetra means four so one two three four you have four copies of the same genes okay and then they do something called crossing over where they actually cross this guy's Crossing his leg with this leg and Crossing arms up here and they switch pieces some pieces from this guy break off and join this one and this guy's pieces join that one all right and so what happens is let's say capital A is brown eyes capital B is brown hair small a is is blue eyes small B is um blonde hair all right so let's say you've got this this from Mom and Mom has brown hair and brown eyes dad has blonde hair and blue eyes all right so they sit next to each other and they switch them parts and now remember this is going to make four cells so this goes to one cell this goes to one cell this goes to one cell and this goes to one cell so let's see what this crossing over has done okay so this one is going to go to one cell and it's going to take brown hair and brown eyes this one is going to go to another cell and it's going to have brown hair they didn't put the a there for some reason brown hair and blue eyes this one goes to one cell and this is going to have blonde hair and brown eyes and this is going to go to another cell and has blonde hair and blue eyes so you can see we have all four combinations of hair and eye color now that that child could have based upon um switching things around and this introduces genetic diversity now the other thing too is that not all of Mom's chromosomes are going to go into one cell and all the dads go into other cells we mix up like a chromosome over here let's say this one goes into a cell and maybe this one goes with it so we're mixing up Mom and Dad's chromosomes and ones that have bits that have been exchanged and we're mixing everything up hoping to get diversity now some people have a lot more diversity in terms of the things that we can see than other people do like you may have a brother or sister that looks nothing at all like you um or you your whole family may look alike like for instance the Olsen twins their whole family looks alike their sister Elizabeth looks like them I think they have a brother too but all the kids look the same so in terms of looks there's not a lot of genetic diversity there may be in terms of you know the different enzymes they make and things like that but um this is when it happens it happens during prophase one and metaphase one of meiosis one okay so this only happens in meiosis one during meiosis II this does not happen and this introduces genetic diversity all right so you can see how here they went to different cells and then these are going to divide again and go to different cells so here you end up with one that has parts of of moms stuck on Dad's chromosome and the other chromosome has parts of dad stuck on the mops these two are both all mom or all that okay um all right so the seminar first two girls have sperm in all stages of development and the sertoli cells and then lighting cells are in between so here's a tubule here's a tubule here's a tubule here light excels in between all right so that so totally cells do all these different things and then here we have our DNA replication tetrad formation and crossing over happens right here all right all right so here's the acrosome and the nucleus then we have the middle piece here that has lots of mitochondria and then the the tail or flagellum okay we produce uh sperm the rate of about three million a day and once ejaculated have a life expectancy of 48 Hours within the female reproductive tract um the egg has a lifespan of 24 hours once ovulation occurs so there has to be an overlap between those 48 hours and the 24 hours that the egg is viable in order for fertilization to occur all right so we've covered this during puberty you start producing gonados releasing hormone and you release LH and FSH L8 stimulates light excels to reduce testosterone FSH stimulates spermatogenesis okay testosterone is controlled by negative feedback system to keep that level steady inhibit inhibits follicle stimulating hormone to regulate the rate of spermatogenesis okay and this shows the negative feedback with using in heaven right so sperm production is sufficient they release inhibit inhibits FSH and decreases sperm production if it's proceeding too slowly less Inhibitors release more FSH is secreted and sperm production is increased okay so the Sperma produced in the tubules they travel or in these seminiferous tubules they travel through this straight tubule to the retail testis and then leave to go to the epididymis through these efferent ducts um the epidemis has stereocilia and is the cytosperm maturation and storage it can stay there for a month after which they're either expelled or degenerate and it'll be absorbed now the epididymis is really highly coiled I think it's like I don't know 20 feet long if you would stretch it out pretty sure that's helped yeah 20 feet long if you uncoil it it's only an inch and a half long if you measure the side of it has a body a tail and a head um and then the tail region continues as the ductus deferens or the vas deferens okay the ductus deferens or seminal ducts stores the sperm propels them forward towards the urethra during ejaculation and it does so through the process of peristalsis which we know so well by now right this chromatic cord we went through the different parts of different things that are in there okay and this is showing again this posterior View there's the prostate the Bobo urethral glands the seminal vesicles and here is the ampulla of the ductus deferens or the vas deferens and the ejaculatory duct okay um so another view of the ejaculatory duct okay this adds fluid to the prostatic urethra just before ejaculation it's about an inch long so the the vas deferens those tubes are about 18 inches long they empty into the prosthetic urethra along with the secretions from the seminal vesicle they can they sperm along through peristaltic contractions um and the stored sperm remained viable for a couple of months so um if