Chapter 3 Part 1 Flashcards by Alyza Gia Kudera

Controls the monthly sexual cycles

Hypothalamus

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produced by the hypothalamus, acts on cells of the anterior lobe (adenohypophysis) of the pituitary gland, which in turn secrete gonadotropins

Gonadotropin-releasing hormone (GnRH)

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Hormones that stimulate and
control cyclic changes in the ovary

follicle-stimulating hormone (FSH)
luteinizing hormone (LH),

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Consequently, most follicles
degenerate without ever reaching full maturity.

TRUE

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proliferation of follicular cells surrounding the oocyte is mediated by

Growth differentiation factor 9

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The hormone is not necessary to promote development of primordial follicles to the primary follicle stage, but without it, these
primary follicles die and become atretic

follicle-stimulating hormone (FSH)

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Theca interna cells produce _______

Androstenedione
Testosterone

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What converts Androstenedione
and Testosterone to estrone and 17 B-estradiol

Granulosa cells

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When a follicle becomes atretic, the oocyte and surrounding follicular cells degenerate and are replaced by connective tissue, forming a

corpus atreticum

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Theca interna and granulosa cells produce ________

Estrogens

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The oocyte is arrested in metaphase approximately how many hours before ovulation?

3 hours

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At midcycle, there is an ________ that:
- Elevates concentrations of maturation promoting factor, causing oocytes to complete
meiosis I and initiate meiosis II
- Stimulates production of progesterone by follicular stromal cells (luteinization)
- Causes follicular rupture and ovulation

LH surge

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High concentration of LH increases what activity that results in the digestion of collagen fibers surrounding the follicle?

Collagenase activity

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What other level also increase in response to the LH surge and cause local ,muscular contractions in the ovarian wall

Prostaglandin Levels

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Some of the cumulus oophorus
cells then rearrange themselves around the zona pellucida to form what?

corona radiata

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German for
“middle pain”

mittelschmerz

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Under the influence of LH, cells develop a yellowish pigment and change into ________ which forms the corpus luteum

Lutein cells

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Progesterone, together with some
estrogen, causes the uterine mucosa to enter the ______________ in preparation for implantation of the embryo.

progestational or secretory stage

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In humans, approximately how many days does it take for the fertilized oocyte to reach the uterine lumen?

3 to 4 days

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If fertilization does not occur, the corpus luteum reaches maximum development approximately how many days after ovulation?

9 days

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Subsequently the corpus luteum shrinks due to luteolysis and forms a mass of fibrotic scar tissue called _________

Corpus albicans

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What prevents the degeneration of corpus luteum if the oocyte is fertilized?

it is also a hormone secreted
by the syncytiotrophoblast of the developing embryo

Human chorionic gonadotropin

By the end of the third month, what is the size of the structure?

one-third to one-half of the total size of the ovary

Yellowish luteal cells continue to secrete progesterone until
the end of the ________ month

fourth

Removal of the corpus luteum of pregnancy before the fourth month usually leads to _______

abortion

The process by which male and female gametes fuse

Fertilization

Where does fertilization occurs?

ampullary region of the uterine tube

Spermatozoa may remain viable in the female reproductive tract for _________

several days

The trip from cervix to oviduct can occur as _____________

rapidly as 30 minutes or as slow as 6 days

Spermatozoa must acquire something before it will be able to fertilize oocyte

Capacitation Acrosome reaction

Is a period of conditioning in the female reproductive tract that in the human lasts approximately 7 hours

Capacitation

Only __________ can pass through the corona cells and undergo the acrosome reaction

capacitated sperm

occurs after binding to the zona pellucida and is induced by zona proteins

acrosome reaction

phases of fertilization

Phase 1, penetration of the corona radiata Phase 2, penetration of the zona pellucida Phase 3, fusion of the oocyte and sperm cell membranes

What phase is when Of the 200 to 300 million spermatozoa normally deposited in the female genital tract, only 300 to 500 reach the site of fertilization. Only one of these fertilizes the egg

Phase 1: Penetration of the Corona Radiata

Phase 2: Penetration of the Zona Pellucida

is a glycoprotein shell surrounding the egg that facilitates and maintains sperm binding and induces the acrosome reaction

Zona

Ligand mediating the binding and the acrosome reaction

ZP3

The initial adhesion of sperm to the oocyte is mediated in part by the interaction of integrins on the oocyte and their ligands, disintegrins, on sperm.

Phase 3: Fusion of the Oocyte and Sperm Cell Membranes

As a result of the release of cortical oocyte granules, which contain lysosomal enzymes the oocyte membrane becomes impenetrable to other spermatozoa

Cortical and zona reactions

penetration of more than one spermatozoon into the oocyte

polyspermy

The oocyte finishes its second meiotic division immediately after entry of the spermatozoon

Resumption of the second meiotic division.

One of the daughter cells, which receives hardly any cytoplasm, is known as the

second polar body

the other daughter cell is the

definitive oocyte

Its chromosomes (22 plus X) arrange themselves in a vesicular nucleus known as the

female pronucleus

The activating factor is probably carried by the spermatozoon. Activation encompasses the initial cellular and molecular events associated with early embryogenesis.

Metabolic activation of the egg

The spermatozoon, meanwhile, moves forward until it lies close to the female pronucleus. Its nucleus becomes swollen and forms the

male pronucleus

Main results of fertilization

Restoration of the diploid number of chromosomes Determination of the sex of the new individual Initiation of cleavage

Without fertilization, how many hours does it take for the oocyte to degenerate after ovulation?

24 hours

Once the zygote has reached the two-cell stage, it undergoes a series of mitotic divisions, increasing the numbers of cells. These cells, which become smaller with each cleavage division, are known as

blastomeres

segregates inner cells, which communicate extensively by gap junctions, from outer cells

compaction

Approximately 3 days after fertilization, cells of the compacted embryo divide again to form a

16-cell morula

line inner cell mass gives rise to tissues of the

embryo proper

the outer cell mass forms the _______, which later contributes to the placenta

trophoblast