Spermatogenesis Leutinizing hormone (LH)(anterior pituitary) stimulates Leydig cells (adjacent to seminferous tubules) to produce testosterone Follicle Stimulating Hormone (FSH) and testosterone stimulate meiotic divisions of spermatogonia into spermatozoa
Reproduction Facts Women are born with all the eggs they will ever have throughout their lifetime (approximately half a milliion) –These eggs are not fully developed/matured until puberty sets in and do not go through final meiosis stage until fertilization Men begin producing sperm upon puberty and produce tens of millions a day. –The biological design of man is to procreate with as many partners as possible. –Survival of the species through numbers
The Outset of Ovulation Every month, one of the two ovaries selects an egg for development Support cells aid in the feeding and development of this egg Eventually the egg and support cells leave the ovary and move into the fallopian tubes (lead to the uterus) Egg has 12-24 hours to become fertilized by sperm or it dies
Fallopian Tubes Lead to Uterus Lined with cilia to help egg along in its journey Egg normally is fertilized here and then implanted in the uterine walls Ectopic pregnancy is when egg implant in wall of fallopian tubes.
Journey of the Sperm Sperm must make passage through vagina…VERY ACIDIC Sperm must pass through mucus plug of cervix…STICKY FINGERS! (do you really want to know?) Uterus is next major passage but sperm gets assistance from uterine contractions Sperm makes it to Fallopian tube –Only one will get to fertilize egg –Sperm caught in cilia lining Fallopian tubes may have better chance to fertilize egg –Chemical changes occur in sperm caught in cilia
Sperm Meets Egg Sperm must attach to receptors on surface of egg The ‘Zona’ is the hard shell of the egg –When sperm lock on, enzymes in that sperm helps to dissolve zona –Membranes then fuse Final meiotic division of egg takes place and polar body picks up extra chromosomes Sperm chromosomes & egg chromosomes then meet
Sperm Meets Egg Approximately five days after fertilization, the fertilized egg has reached the uterus One cell has divided into about one hundred cells at this point; Still inside the zona On the sixth day (approximately), cells break out of zona and implant in uterine lining and away from mom’s immune system About two weeks later, gastrulation starts and cells differentiate
Hormonal Functions/Roles Follicle Stimulating Hormone (FSH)Follicle Stimulating Hormone (FSH) –Anterior pituitary hormone –Stimulates the production of germ cells via the ovarian follicles –Works synergistically with LH Luteinizing Hormone (LH)Luteinizing Hormone (LH) –Anterior pituitary hormone –LH surges initiate ovulation –Helps to develop the corpus luteum (temporary endocrine structure)
Hormonal Functions/Roles ProgesteroneProgesterone –Steroid hormone –Produced by corpus luteum –Aids in gestation EstrogenEstrogen –Regulation of menstrual cycle –Develop secondary sexual characteristics in females (and males too…hold the soy please!)
Hormonal Functions/Roles TestosteroneTestosterone –Pre-natal development of male genitalia –Develops male secondary sexual characteristics (in ladies too…hold the steroids please!) –Assists in male sex drive/libido
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