Reproductive system and Development
Male reproductive structures
Menstrual cycle
Meiosis- makes gametes, 4 unique haploid gametes
Embryonic development
Hormones
Female reproductive structures
Male
Female
Fetal development
Ovarian follicles in ovaries consist of follicle cells surrounding an oocyte. The different types are for each different stage
hormone levels
effects on endometrium
Ovarian follicular stages
1st:Primordial follicle-primary oocyte-single layer of cells around oocyte.
2nd:Primary follicle-primary oocyte-single/multiple layers cuboidal granulosa cells around an oocyte
3rd:Secondary follicle-primary oocyte- multiple layers of granulosa cells surround oocyte and small antrum.
4th:Vesicular follicle- secondary oocyte- multiple layers of granulosa cells surround oocyte and large antrum.
5th:Corpus luteum-no oocyte- yellow collapsed fold of granulosa cells.
6th:Corpus albicans-no oocyte- remnant of corpus luteum, connective scar tissue
2 Ovaries-lateral to the uterus, from outside in is the germinal epithelium, tunica albuginea, cortex, and medulla.
2 Fallopian tubes: extend laterally from uterus to both ovaries.
Ampulla- expanded region medial to infundibulum where fertilization usually occurs
isthmus-medial to ampulla towards uterus, 1/3 length of tube
Infudibulum- funnel-shaped with fimbriae that enclose the ovary during ovulation
uterine part- medial to isthmus and penetrates uterus wall
Uterus/Womb- pear shaped, thick walled muscular organ.supports, protects, and nourishes the developing embryo/fetus. layers include perimetrium, myometrium, and endometrium.
Vagina- thick walled, inferiormost fibromuscular tube that is 10 cm in length. Birth canal, connects uterus to the outside of the body, passageway for menstruation
Fundus- curved superior region extending between fallopian tubes
Body of uterus- middle region, thick wall of smooth muscle
Anteverted- anterosuperiorly across the superior surface of the bladder.
Retroverted- posterosuperiorly, projecting towards the rectum
isthmus-constricted inferior region of the body
Cervix- narrow inferiormost portion of the uterus projects into vagina. includes Internal os, cervical canal, and external os.
250 lobules in each teste, the testes are in a sac called the scrotum which provides cooler environment needed for sperm development
Rete testis receive sperm from seminiferous tubules and merge to form efferent ductules (12-15 each teste).
Seminiferous tubules- thin and elongated. 4 per lobule. contain sustentacular cells and germ cells.
efferent ductules drain into the epididymis. the epididymis stores sperm until they are fully mature.
interstitial spaces- spaces surrounding seminiferous tubules. interstitial cells are in this space, which produce androgens
Penile urethra- transports semen from both ejaculatory ducts to the outside of body
Luteinizing LH- from anterior pituitary- stimulates ovulation
Estrogen- from ovarian follicles before ovulation/corpus luteum after ovulation/placenta during pregnancy. initiates and maintains growth of endometrium
Follicle-stimulating FSH- from anterior pituitary. stimulates development and maturation of ovarian follicles
progesterone- from corpus luteum/ placenta during pregnancy. causes increase in blood vessel distribution, uterine gland size, and nutrient production
Gonadotropin-releasing GnRH- from hypothalamus. stimulates ant.pituitary to secrete FSH & LH
Inhibin- from ovarian follicles. inhibits FSH secretion to prevent excessive follicular development
Follicle-stimulating FSH- from anterior pituitary. stimulates interstitial cells to secrete testosterone
testosterone- stimulates spermatogenesis, inhibits GnRH secretion
Gonadotropin-releasing GnRH- from hypothalamus. stimulates ant.pituitary to secrete FSH & LH
Inhibin-inhibits FSH secretion
Days 6-13 Follicular phase: estrogen and inhibin inhibit the hypothalamus & anterior pituitary which causes a drop in FSH. 1 follicle continues to mature and produce estrogen
Day 14 Ovulation: increase in estrogen above threshold stimulates hypothalamus & anterior pituitary causing LH surge inducing ovulation
Days 1-5 Follicular phase: GnRH stimulates FSH and LH secretion, some ovarian follicles develop and produce estrogen
Days 15-28 Luteal phase: Corpus lutem forms & secretes large amounts of estrogen, progesterone, and inhibin. all of these comined inhibit GnRH FSH and LH secretion.
Days 1-5 Menstrual phase: functional layer of the endometrium is shed
Days 6-14 proliferative phase: functional layer of endometrium rebuilds
Day 15-28 Secretory phase: functional layer sloughs off
Progesterone stimulates uterine lining growth but if an oocyte is not fertilized, the corpus lutem regresses and hormone levels drop
Ductus deferens- sperm leaves epididymis and enters the vas deferens, thick walled tube
Ampulla of vas deferens- unites with the proximal region of the seminal vesicle to form the ejaculatory duct (1-2 cm long) which conducts sperm and seminal fluid towards urethra
Prostate gland- walnut shaped 20grams. inferior to bladder. secretes milky fluid that is weakly acidic and rich in citric acid, seminalplasmin, and PSA.
Bulbourethral glands- secrete clear mucus that protects the urethra and serves as lubricant during intercourse
Seminal vesicles- lateral to ampulla. secrete a viscous whitish-yellowish alkaline fluid containing both fructose and prostaglandins
Week 4: basic human body plan is established, cylindrical embryo, limb buds appear, derivatives of the three germ layers begin to form, 4mm
Week 5-8: head enlarges, eyes ears and nose appear, mandibular arch forms, major organ systems formed , 30mm
Week 3: establishment of the three primary germ layers through the process of gastrulation. 1.5mm
Weeks 21-38: body gains major amount of weight, brows and lashes appear, subcutaneous fat is deposited, eyelids open, Testes descend into scrotum (male), 53cm, 2.5-4.5 kg
Weeks 17-20: muscle movements become stronger and frequent, lanugo and vernix caseosa covers skin, limbs near final proportions, 19 cm, 454 grams
Weeks 13-16: body grows rapidly, limbs become more proportionate, brain and skull continue to enlarge, ossification in skeleton continues, 14cm, 170 grams
Weeks 9-12: primary ossification centers appear in most bones, reproductive organs begin to develop, brain grows, body gets longer, palate of mouth develops, 9cm, 28 grams
Mesoderm- middle layer,muscles, bones, some organs
Endoderm- digestive tract, inferior layer
Ectoderm- superior layer, Skin, nervous system
Spermatogenesis
Oogenesis
Spermiogenesis: newly formed spermatids differentiate to become anatomically mature sperm.
Meiosis II: originates with the secondary spermatocytes and produces spermatids
Meiosis I: begins in the diploid primary spermatocytes. haploid cells produced during meiosis I are secondary spermatocytes
Mitotic division- spermatogonia are primordial germ stem cells that contain 23 pairs of chromosomes.mitotic divisions of spermatogonia produce a new germ cell and a committed cell calked a primary spermatocyte
Childhood- Ovary is inactive, houses primordial follicles. meiosis I arrested.
Monthly from puberty to menopause- about 20 primordial follicles mature into primary follicles every month. some mature into secondary follicles.
Before birth- Oogonia are diploid cells (origin of oocytes) containing 23 pairs of chromosomes. mitotic divisions of oogonia produce primary oocytes. primary oocytes begin meiosis but stop at prophase I
usually only 1 secondary follicle matures into a vesicular follicle. primary oocyte completes meiosis I producing a polar body and a secondary oocyte (23 chromosomes) which is paused in meiosis metaphase II
if secondary oocyte is fertilized then it will complete the 2nd meiotic division and becomes an ovum. if its not fertilized then it degenerates
Meiosis 2
Meiosis I
Metaphase 1- chromosomes pairs line up forming a double line of chromosomes
Antaphase1- separate pairs of chromosomes to opposite sides of cell (reduction division)
Prophase 1- nuclear membrane goes away, Crossing over occurs between homologous maternal and paternal chromosomes (tetrad)
Telephase 1- 2 new haploid nuclei, each containing 23 chromosomes
Anaphase2- sister chromatids of each replicated chromosome are pulled apart, sister chromatids migrate to opposite ends
Metaphase2- replicated chromosomes align along the equator of the cell
Telophase2- single chromosomes arrive at opposite ends of cell and nuclear membrane reforms
Prophase2- nuclear envelop breaks down, replicated chromosomes cluster together
*Meiosis stops after T2*