WVSOM - Embryology Word Scramble
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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
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