AHL 11.4

11.4.1 Annotate a light micrograph of testis tissue to show the location and function of interstitial cells (Leydig cells), germinal epithelium cells, developing spermatozoa and Sertoli cells. Testis Structure

11.4.2 Outline the processes involved in spermatogenesis within the testis, including mitosis, cell growth, the two divisions of meiosis and cell differentiation. Spermatogenesis

11.4.3 State the role of LH, testosterone and FSH in spermatogensis.

11.4.3 State the role of LH, testosterone and FSH in spermatogensis. FSH is produced an released by the _____________________ and stimulates meiosis of the __________________________, giving _________________________ (now haploid). LH is also released and reaches the ____________________ of the testis, where it stimulates ____________________ production. Testosterone stimulates the final meiotic division and differentiation of the _______________ to form mature_________________.

11.4.7 Outline the role of the epididymis, seminal vesicle and prostate gland in the production of semen.

11.4.6 Draw and label a diagram of a mature sperm and egg. Cells in the germinal tissue, called spermatogonia, are diploid (2n) and divide many times by mitosis to produce an endless supply of diploid cells. The cells formed by mitosis are displaced inwards and grow large enough to divide by meiosis, called primary spermatocytes (2n). The enlarged cells carry out the first division of meiosis, halving the chromosome number, producing 2 secondary spermatocytes (n). The two haploid cells (each secondary spermatocyte) carry out the second division of meiosis, producing 4 spermatids. The four cells become attached to a Sertoli cell, which feeds them as they develop into sperm. Mature sperm (the spermatozoa) detach from Sertoli cells and eventually are carried out of the testes by fluid in the center of the seminiferous tubule. Role of hormones in spermatogenesis: There are two hormones secreted from the pituitary FSH and LH. FSH regulates the mitotic divisions of spermatocytes. Stimulates primary spermatocytes to undergo the first division of meiosis. LH stimulates Leydig cells to produce testosterone Testosterone (produced by Leydig cells) promotes Sertoli cells function, stimulates the maturation of secondary spermatocytes through meiosis and differentiation to spermatozoa.

11.4.3 Annotate a diagram of the ovary to show the location and function of germinal epithelium, primary follicles, mature follicle and secondary oocyte.

11.4.5 Outline the processes involved in oogenesis within the ovary, including mitosis, cell growth, the two divisions of meiosis, the unequal division of cytoplasm and the degeneration of polar body.

11.4.6 Draw and label a diagram of a mature sperm and egg.

11.4.8 compare the processes of spermatogenesis and oogenesis, including the number of gametes and the timing of the formation and release of gametes.

11.4.9 Describe the process of fertilization, including the acrosome reaction, penetration of the egg membrane by a sperm and the cortical reaction. Sperm released into the vagina during sexual intercourse are stimulated to swim by calcium ions diffusing from vaginal fluids into their tail. The membranes of sperm have receptors that can detect chemicals released by the egg, allowing directional swimming towards the egg. Once the egg is reached, these events take place: The acrosome reaction: When the sperm makes contact with the zona pellucida, the contents of the acrosome are released and the enzymes from it loosen the zona pellucida. This allows sperm to force their way through by vigorous tail beating. Penetration of the egg membrane: The plasma membrane of the sperm and the egg fuses. This stimulates the release of Ca in the egg, in turn stimulating the meiosis II in the nucleus. The cortical reaction: At the same time, the cortical granules (vesicles located near the egg membrane) release their content and cause the zona pellucida to thicken and separate from the oocyte. The zona pellucida is now an impenetrable membrane, can no longer bind with the sperm. This prevents further entry of sperm and protects the developing of the embryo during its first days of life. The nucleus of the sperm is posted into the cytoplasm of the egg.

11.4.9 Describe the process of fertilization, including the acrosome reaction, penetration of the egg membrane by a sperm and the cortical reaction. Sperm released into the vagina during sexual intercourse are stimulated to swim by calcium ions diffusing from vaginal fluids into their tail. The membranes of sperm have receptors that can detect chemicals released by the egg, allowing directional swimming towards the egg. Once the egg is reached, these events take place: The acrosome reaction: When the sperm makes contact with the zona pellucida, the contents of the acrosome are released and the enzymes from it loosen the zona pellucida. This allows sperm to force their way through by vigorous tail beating. Penetration of the egg membrane: The plasma membrane of the sperm and the egg fuses. This stimulates the release of Ca in the egg, in turn stimulating the meiosis II in the nucleus. The cortical reaction: At the same time, the cortical granules (vesicles located near the egg membrane) release their content and cause the zona pellucida to thicken and separate from the oocyte. The zona pellucida is now an impenetrable membrane, can no longer bind with the sperm. This prevents further entry of sperm and protects the developing of the embryo during its first days of life. The nucleus of the sperm is posted into the cytoplasm of the egg.

11.4.9 Describe the process of fertilization, including the acrosome reaction, penetration of the egg membrane by a sperm and the cortical reaction. Sperm released into the vagina during sexual intercourse are stimulated to swim by calcium ions diffusing from vaginal fluids into their tail. The membranes of sperm have receptors that can detect chemicals released by the egg, allowing directional swimming towards the egg. Once the egg is reached, these events take place: The acrosome reaction: When the sperm makes contact with the zona pellucida, the contents of the acrosome are released and the enzymes from it loosen the zona pellucida. This allows sperm to force their way through by vigorous tail beating. Penetration of the egg membrane: The plasma membrane of the sperm and the egg fuses. This stimulates the release of Ca in the egg, in turn stimulating the meiosis II in the nucleus. The cortical reaction: At the same time, the cortical granules (vesicles located near the egg membrane) release their content and cause the zona pellucida to thicken and separate from the oocyte. The zona pellucida is now an impenetrable membrane, can no longer bind with the sperm. This prevents further entry of sperm and protects the developing of the embryo during its first days of life. The nucleus of the sperm is posted into the cytoplasm of the egg.

11.4.10 Outline the role of HCG in early pregnancy. 11.4.11 Outline early embryo development up to the implantation of the blastocyst. HCG Progesterone Estrogen After fertilization, the zygote starts to divide by mitosis, forming a ball of cells called the blastocyst. It takes the blastocyst 5-7 days to reach the uterus and embed in the endometrium in a process called implantation. When the blastocyst implants into the endometrium, it starts to release HCG (Human Chorionic Gonadotrophin). This hormone causes the corpus luteum to continue to proliferate and to secrete increasing levels of progesterone and estrogen so that the endometrium is maintained. The level of HCG in maternal blood is so high that it is present in the urine, which allows to be detected for pregnancy tests.   HCG: Secretion of Progesterone and Estrogen by ________________ Progesterone and Estrogen _______ FSH-LH – so no more eggs are released Progesterone maintain _____________, where the _________ develops into a fetus and the ___________ forms

11.4.13 State that the fetus is supported and protected by the 11.4.12 Explain how the structure and functions of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy. 11.4.13 State that the fetus is supported and protected by the amniotic sac and amniotic fluid. 11.4.14 State that the materials are exchanged Between the maternal and fetal blood In the placenta. Functions of the placenta Releases _____________ and _________ Exchange of materials between _________ and ________ blood (blood does not mix) During the 2-4 weeks of development the embryo obtains nutrients directly from the endometrium (the uterus lining). Tissues grow out of the developing embryo and mingle with the endometrium to form the placenta. The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination and gas exchange via the mother's blood supply. Diffusion of material between the maternal and embryonic circulatory systems provides nutrients, exchanges respiratory gases and disposes of metabolic wastes for the embryo. Blood from the embryo travels to the placenta through the arteries of the umbilical cord and returns though the umbilical vein. The embryo secretes hormones that signal its presence and controls the mother’s reproductive system. HCG acts like luteinizing hormone to maintain secretion of progesterone and estrogen. The fetus is supported and protected by the amniotic sac and amniotic fluid. Placenta structure & function: Rich blood supply: Deoxygenated blood and waste out via umbilical arteries Oxygenated blood and useful materials via umbilical vein Placental villi: Increase surface area for exchange Mother’s arteries deliver blood into the intervillous space, bathing the villi of the placenta for maximal exchange of materials. There are few membranes between the maternal blood and the fetal blood, an association that is closer than an other mammal. This also gives a short diffusion path for materials. The endometrium which is maintained through out pregnancy by progesterone. Initially from the corpus luteum and later from the placenta itself. Other hormones such as HCG and estrogen are also produced by the placenta. Placenta secretes anti-immune substances to avoid attack by immune system.

Rich ____________________ Few thin membranes give a ____ 11.4.12 Explain how the structure and functions of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy. Rich ____________________ Few thin membranes give a ____ ______________ for materials. ______ increase surface area for exchange Placenta has a _______________ and many RER and vesicles for production of ____________ (estrogen and progesterone) During the 2-4 weeks of development the embryo obtains nutrients directly from the endometrium (the uterus lining). Tissues grow out of the developing embryo and mingle with the endometrium to form the placenta. The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination and gas exchange via the mother's blood supply. Diffusion of material between the maternal and embryonic circulatory systems provides nutrients, exchanges respiratory gases and disposes of metabolic wastes for the embryo. Blood from the embryo travels to the placenta through the arteries of the umbilical cord and returns though the umbilical vein. The embryo secretes hormones that signal its presence and controls the mother’s reproductive system. HCG acts like luteinizing hormone to maintain secretion of progesterone and estrogen. The fetus is supported and protected by the amniotic sac and amniotic fluid. Placenta structure & function: Rich blood supply: Deoxygenated blood and waste out via umbilical arteries Oxygenated blood and useful materials via umbilical vein Placental villi: Increase surface area for exchange Mother’s arteries deliver blood into the intervillous space, bathing the villi of the placenta for maximal exchange of materials. There are few membranes between the maternal blood and the fetal blood, an association that is closer than an other mammal. This also gives a short diffusion path for materials. The endometrium which is maintained through out pregnancy by progesterone. Initially from the corpus luteum and later from the placenta itself. Other hormones such as HCG and estrogen are also produced by the placenta. Placenta secretes anti-immune substances to avoid attack by immune system.

11.4.15 Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin levels and positive feedback.

11.4.15 Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin levels and positive feedback.