Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
WVSOM - Embryology
Gametogenesis
| Question | Answer |
|---|---|
| Fertilization | Within 24 hours of ovulation |
| Blastocyst formation and implantation | Day 6 |
| Primitive streak gastrulation | Day 15 to week 4 |
| Somite formation complete, most primordial body structures generated | Week 5 |
| Gonad | A gamete producing organ |
| Testis/testicle | Male gonad |
| Ovary | Female gonad |
| Germ line | Gametes and gametic precursor cells |
| Somatic tissue | Any non-germ line tissue |
| Primordial germ cells | Earliest stem cells for the entire germ line |
| Gametes | Eggs and sperm; haploid reproductive cells that fuse to produce new individuals |
| Sperm | Gametes produced by males, small and motile |
| Spermatozoa | Mature sperm |
| Eggs | Gametes produced by females, large and immotile |
| Ovum | Mature egg |
| Gametogenesis | Gamete formation |
| Spermatogenesis | Spermatozoa formation (spermatogonia to spermatozoa) |
| Spermiogenesis | Spermatozoa maturation (spermatids to spermatozoa) |
| Oogenesis | Ovum formation (oogonium to ova) |
| Where are primordial germ cells found? | In the wall of the yolk sac, after 3 weeks of embryogenesis |
| How do primordial germ cells move? Where do they move to? | By ameboid movement; move to the genital (gonadal) ridge by end of 4th week |
| What does the genital ridge develop into? | Testis in males and ovaries in females |
| What do the primordial germ cells develop into? | Germ line of the gonad |
| Seminiferous tubules | Testicular sex cords that develop lumens (shortly before puberty); primordial germ cells differentiate into spermatogonia |
| Spermatogonia (4n - 2n - 4n - 2n - 4n - 2n - 4n - 2n - 4n - 2n) | Stem cells that maintain male germ line by mitotic division; located at base of epithelium of seminiferous tubules (near basal lamina) |
| Sertoli cells | Cells that provide support and nutrition to differentiating sperm cells; also assist in release of spermatozoa into lumen of seminiferous tubules |
| Incomplete cytokinesis | Clusters of spermatogonia cells connected by cytoplasmic bridges |
| Primary spermatocytes (4n) | Differentiating spermatogonia that have undergone several rounds of mitosis and entered into meiosis I; prolonged prophase (22 days) followed by rapid completion of meiosis I |
| Secondary spermatocyte (2n) | Meiosis II |
| Spermatids (1n) | Completed second meiotic division |
| Flagellum of spermatozoa | Develops neck, middle piece, principle piece, end piece; all four regions have typical 9+2 microtubular arrangement; middle piece encricled by mitochondria |
| Acrosome of spermatozoa | Develops from acrosomic granule; cap-like structure that covers most of nucleus; contains enzymes required for penetration of egg |
| How long does spermatogenesis take? | ~64 days |
| Residual bodies | Cytoplasmic remains, left with sertoli cells after mature spermatozoa released into lumen (of seminiferous tubules) |
| How are spermatozoa pushed towards the epididymis? | By contractile elements of the wall of the seminiferous tubules; initially they (spermatozoa) only have limited motility; develop full motility in epididymis |
| Oogonia | Differentiated primordial cells that have reached developing ovary |
| How do oogonia proliferate? | Mitotically |
| What are oogonia surrounded by toward the 3rd month of gestation? | Follicular cells (form a squamous epithelium) |
| Primary oocyte | Differentiated oogonia that have entered meiosis and arrested in prophase I (diplotene stage) |
| Primordial follicles | Primary oocytes surrounded by follicular cells |
| Atresia | Primordia follicles, along with oocytes, degenerate |
| How many germ cells exist at peak level (females)? | ~7 million |
| How many primordial follicles persist at the 7th month (females)? | 2 - 0.7 million |
| How many primordial follicles will persist by puberty (females)? | ~400,000 |
| How many primordial follicles with eventually ovulate? | ~500 |
| Where does differention of primordia follicles into primary follicles begin? | In the fetus (continues until menopause) |
| What is needed for primary follicles to mature? | FSH (follicle stimulating hormone); not produced until puberty |
| What happens to primary follicle not indcued by FSH? | They regress by atresia, becoming a mass of connective tissue known as corpus atreticum |
| How many primary follicles does FSH induce to initiate maturation each menstrual cycle? | 20-25; usually only one completes maturation and ovulates, the rest undergo atresia |
| Stroma cells | Support cells; form follicles |
| Granulosa cells | Stroma that have become cuboidal in shape (primary follicle onward) |
| Theca folliculi | Stroma cells on o/s of granulosa epithelium in secondary follicle |
| Theca externa | Fibroblast-like connective cells (from theca folliculi); shell around follicle; outer layer |
| Theca interna | Inner layer of secretory cells; produce estrogen (in conjunction with granulosa cells) - prepares female reproduction system for embryo implantation |
| Zona pellucida | Secretion of glycoprotein layer from oocyte and granulosa cells on surface of oocyte; sperm attachment; prevents polysperm |
| Corpus luteum | Secretes progesterone; feeds endometrium |
| Primary follicles | Develop from primordial follicles; oocytes enlarge; squamous folliclular cells transform into granulosa cells, which form simple cuboidal epithelium |
| Secondary follicles | Developed from primary follicles; granulosa cells develop into stratified epithelium |
| Antral follicle (aka graafian follicle) | Forms when fluid-filled space (known as antrum) develops between granulosa cells |
| Cumulus oophorus | Granulosa cells that remain around oocyte |
| What size are antral/graafian follicles? | > 20mm in diameter |
| What happens due to unequal cytokinesis? | One daughter cell inherits most of the cytoplasm; the other daughter cell without the cytoplasm is known as a polar body |
| Secondary ooctye | Daughter cell that received most of the cytoplasm during unequal cytokinesis; start of meiosis II |
| The germ cell (ovum/egg) arrests in what meiotic II stage until fertilization? | Metaphase II; if fertilization does not occur, the ovum degenerates |
| When does ovulation occur? | Soon after ovum reaches metaphase II |
| What surrounds the ovum after rupture from the ovary? | Corona radiata |
| Oviduct | Fallopian tube |
| Corpus luteum | Remains of the follicle left in the ovary after rupture; secretes hormones (progesterone) which prepares uterus for implantation and nourishment of embryo |
| Corpus albicans | Regression of corpus luteum into mass of scar tissue if ovum not fertilized (~14 days after ovulation) |
| Mittelschmerz | Fluid and blood released from point of ovulation that irritates pelvic peritoneum |
| Menstrual cycle | Lasts ~28 days |
| Where is FSH secreted from? | Pituitary gland |
| Pituitary gland releases FSH in response to? | Gonadotropin-releasing hormone (GnRH) from the hypothalamus |
| Release of GnRH marks what stage of the menstrual cycle? | Proliferation or follicular phase |
| What does estrogen produced by granulosa and thecal cells induce? | Spongy and compact layers of uterine endometrium to proliferate |
| Corpus atreticum | Estrogen secretions that persist from each follicle until they become atretic and regress into mass of connective tissue |
| Secretory / progestational phase | LH induces remnant graafian follicle left in ovary to transform into corpus luteum (yellow body) |
| Lutean cells | Granulosa and theca interna cells that grow into progesterone secreting cells |
| How is progesterone similar to estrogen? | Induces endometrium to proliferate; secretion from corpus luteum causes endometrium to proliferate to max, marks secretory phase; prime time for conception |
| Menstrual phase | Progesterone secretion ceases, spongy and compact layers of endometrium slough off, produces menstrual "bleeding"; day 1 of menstrual cylce = onset of bleeding |
| Corpus luteum of pregnancy / corpus luteum graviditatis | Fertilization; embryo develops into blastocyst; trophoblast secretes hCG; hormone induces corpus luteum to grow, constitutes 1/3-1/2 total size of ovary; structure secretes progesterone |
| When does the corpus luteum regress | 4th month; trophoblast component of placenta secretes enough progesterone to maintain endometrium; increased risk for placental abruption (separation of placenta from uterine wall) |
| What is tested in home pregnancy tests? | hCG - human chorionic gonadotropin |
Created by:
JaneO
Popular Anatomy sets