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USC BISC 307L - Reproduction (continued)
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Structure of Testesmostly seminiferous tubulesleydig cells in between the tubules are the testosterone secreting cellsbig cells – sertoli cells – surround and nourish spermsmall cells- spermatogonia stem cellsdifferentiation occurs as they moveacrosome contains enzymes and carbohydrates that swell when they contact water so that they can penetrate the oocytetakes 70 days before you get sperm- every day several hundred million sperm are producedif not ejaculated they just get destroyedEndocrine Control of Testicular FunctionControl begins with the GnRh secreted in the hypothalamusTestosterone feeds back and stimulates the sertoli cellsReproduction 2Female Reproductive Anatomyovary is where testes used to be – the follicle produces the oocytemature oocyte expelled into the abdomen into the oviduct where it is stored for a while. If there are sperm present during this time then fertilization can occurlong trip for the spermthe zygote stays there and them moves down to the uterus to be implantedthe uterus has three layers1. Endometrium2. Myometrium3. Outer connective tissuecervix is the opening between the uterus and upper part of the vagina- locked with a acidic mucus plug and acts as a barrier to sperm penetration and bacteriaDevelopment of the Ovarian Follicle- 1Ovarian follicleOogenesisFemale fetus- several million oogonia (stem cells) will be produced during fetal life and begin meiosis during fetal life but then become arrested during the first meiotic division (primary oocytes) later some of these oocytes will be surrounded by a single layer of granulose cells (like sertoli cells). These become the primary follicles (2 million at time of birth)Every day starting at birth and continuing throughout life about 30 of these primary follicles begin to differentiate along the path in the drawing but unless the hormone levels are appropriate then the oocytes will not complete differentiation and die. This means that you run out about 45 50 years oldBUT in 2004, conflicting evidence in adult female mice which had small numbers of stem cells in their ovaries that are oocyte stem cells which was not thought to exist in adult femalesThey were able to show that this is true and they are capable of producing oocytes and capable of producing little miceLast month, show that in the ovaries of reproductive age women there are these stem cells that can give rise to mature oocytes competent for fertilizationSecondary follicle with a few layers (basal lamina and theca cells)- analogous to the leydig cellsEndocrine Control Ovarian Functiongranulosa cell converts testosterone to estradiolwhich stimulates granulosa cellspositive feedback in rapid growth of the follicleDevelopment of the Ovarian Follicle-2Secondary follicleneeds FSH to continue (why of the 900 follicles that begin this process only a handful of them will continue when FSH is at the exact right level) cells proliferate and secrete fluid from granulose cells which become the antrumand the follicle begins bulging on the surface of the ovarypressure inside the antrum builds meanwhile the outlying tissue is being digested this positive feedback causes levels of estradiol to rise and the pressure in the antrum grows until there is a rupture in the follicleoocyte expelled into the abdomenremnants of the follicle are called the corpus luteum (made of granulosa cells-produces estradiol and progesterone) LH causes the yellowing of this and causes ovulationthe corpus luteum requires gonadotropin support and the high levels of estrogen are inhibiting FSH and LH secretion so if fertilization doesn’t occur, the feedback inhibition will cause the corpus luteum will regress and become the corpus albicansBISC 307L 1st Edition Lecture 20 Current Lecture- Structure of Testesoo mostly seminiferous tubules o leydig cells in between the tubules are the testosterone secreting cellso big cells – sertoli cells – surround and nourish sperm o small cells- spermatogonia stem cells o differentiation occurs as they move o acrosome contains enzymes and carbohydrates that swell when they contact water so that they can penetrate the oocyteo takes 70 days before you get sperm- every day several hundred million spermare produced o if not ejaculated they just get destroyed- Endocrine Control of Testicular Functionoo Control begins with the GnRh secreted in the hypothalamuso Testosterone feeds back and stimulates the sertoli cells Reproduction 2- Female Reproductive Anatomyo ovary is where testes used to be – the follicle produces the oocyteo mature oocyte expelled into the abdomen into the oviduct where it is stored for a while. If there are sperm present during this time then fertilization can occur o long trip for the sperm o the zygote stays there and them moves down to the uterus to be implantedo the uterus has three layers 1. Endometrium 2. Myometrium 3. Outer connective tissueo cervix is the opening between the uterus and upper part of the vagina- locked with a acidic mucus plug and acts as a barrier to sperm penetration and bacteria - Development of the Ovarian Follicle- 1 o Ovarian follicle Oogenesis Female fetus- several million oogonia (stem cells) will be producedduring fetal life and begin meiosis during fetal life but then become arrested during the first meiotic division (primary oocytes) later some of these oocytes will be surrounded by a single layer of granulose cells(like sertoli cells). These become the primary follicles (2 million at time of birth) Every day starting at birth and continuing throughout life about 30of these primary follicles begin to differentiate along the path in the drawing but unless the hormone levels are appropriate then the oocytes will not complete differentiation and die. This means that yourun out about 45 50 years old BUT in 2004, conflicting evidence in adult female mice which had small numbers of stem cells in their ovaries that are oocyte stem cells which was not thought to exist in adult females They were able to show that this is true and they are capable of producing oocytes and capable of producing little mice  Last month, show that in the ovaries of reproductive age women there are these stem cells that can give rise to mature oocytes competent for fertilization  Secondary follicle with a few layers (basal lamina and theca cells)- analogous to the leydig cells - Endocrine Control Ovarian Functionoo granulosa cell converts


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