L2: Fertilization

Question 1

Egg

Answer 1

Large (~100 μm)
Round, symmetrical, nonmotile cell
arrested i metaphase 2 of meiosis
microvilli in the surface

Question 2

Glycoprotein coat acting as a barrier to the sperm

Answer 2

Zona pellucida

Question 3

3 layers covering an egg

Answer 3

Corona radiata
Zona pellucida
Vitelline membrane

Question 4

Sperm

Answer 4

small, asymmetrical and motile cell
end product of spermatogenesis

Question 5

3 Components of Sperm

Answer 5

Tail
Midpiece
Head with Acrosome

Question 6

also referred to as principal piece that contains the flagellar apparatus and is what makes the cell motile

Answer 6

Tail

Question 7

contains mitochondria and helps in propelling

Answer 7

Midpiece

Question 8

lysosomal-like compartment derived from the Golgi Apparatus; contains soluble hyrdolases

Answer 8

Head c Acrosome

Question 9

Fertilization

Answer 9

process by which the sperm and secondary oocyte fuse

Question 10

where does fertilization occur

Answer 10

ampullary region of uterine tube (widest part of tube)

Question 11

how much spermatozoa is deposited in vagina during intercourse

Answer 11

2-5 million

Question 12

life span of sperm in female reproductive tract

Answer 12

3-7 days

Question 13

at day 14 after the last day of menstrual period, what are the 2 hormones seen

Answer 13

(1) follicle stimulating hormone/FSH (releases follicle that has the egg inside)

(2) luteinizing hormone/LH (increases progesterone, making the uterus lining thick)

Question 14

what propels the egg

Answer 14

fimbriae and mucus

Question 15

percentage of spermatozoa that successfully meets the egg

Answer 15

1%

Question 16

subject to physical stress d/t:

Answer 16

Ejaculation
Contractions in female tract
Change in pH environment
Mucous secretions
Defenses of female immune system
Anatomy of the fallopian tube (double tract,narrower)

Question 17

Ovulation

Answer 17

sperm become motile again

Question 18

spermatozoa has to undergo ___ & ___ to acquire the capability to fertilize the oocyte

Answer 18

Capacitation
Acrosome Reaction

Question 19

Capacitation

Answer 19

period of conditioning in female reproductive tract that lasts ~7 hrs

a glycoprotein coat & seminal plasma proteins are removed from plasma membrane overlying the acrosomal region of the spermatozoa

capacitated sperm = can pass through corona cells = undergo acrosome reaction

bicarbonate ions enter sperm & hyperpolarizes sperm’s plasma membrane affecting the motility of sperm

Question 20

Acrosome Reaction

Answer 20

membrane surrounding acrosome dissolves to fuse c plasma membrane (of sperm head) releasing contents of acrosome

has antigen for binding to cell membrane of egg & lytic enzyme

occurs after binding to the zona pellucida

induced by zona proteins

Question 21

Hyaluronidase

Answer 21

assists in penetration of corona radiata barrier

Question 22

Trypsin-like substance

Answer 22

needed for digestion of zona pellucida

Question 23

Acrosin

Answer 23

needed to help cross the zonal pellucida

Question 24

once sperm enters, the oocyte proceeds to ___

Answer 24

meiosis 2

Question 25

Spermatozoa dies within ___ of their release

Answer 25

24 hrs

Question 26

Trip of spermatozoa from uterus to cervix lasts

Answer 26

30 mins to 6 days

Question 27

Oocyte travel via ___ & ___

Answer 27

ciliary beat rhythmical contraction of muscle of tube

Question 28

Phases of Fertilization

Answer 28

1. Penetration of Corona Radiata 2. Penetration of Zona Pellucida 3. Fusion of oocyte and sperm cell membranes

Question 29

Phase 1: Penetration of the Corona Radiata

Answer 29

only 300 to 500 (out of 200 - 300 M spermatozoa) reach the site of fertilization only one fertilizes the egg others aid fertilizing sperm in penetrating barriers protecting the female gamete capacitated sperms pass freely through coronal cell

Question 30

Zona Pellucida

Answer 30

glycoprotein shell surrounding the egg facilitates and maintains sperm binding & induces acrosome reaction has 5 zones

Question 31

Phase 2: Penetration of the Zona Pellucida

Answer 31

occurs in ZP3 of Z Pellucida release of acrosomal enzymes (acrosin) allows sperm to penetrate zona = coming in contact c plasma membrane of oocyte results in release of lysosomal enzymes from cortical granules lining the plasma membrane of oocyte & alters properties of ZP (zona reaction) to prevent sperm penetration (block to polyspermy)

Question 32

Phase 3: Fusion of Oocyte and Sperm Membranes

Answer 32

initial adhesion of sperm to oocyte is mediated in part by the interaction of integrins on the oocyte and their ligands, disntegrins, on sperm after adhesion, plasma membranes of sperm and egg fuse in humans, both head and tail of spermatozoon enter cytoplasm of oocyte, but plasma membrane is left behind on oocyte surface

Question 33

Path of Sperm Cell

Answer 33

1. Corona Radiata 2. Zona Pellucida 3. Plasma membrane of secondary oocyte 4. Cytoplasm of secondary oocyte

Question 34

Egg Response: Cortical and Zona Reactions

Answer 34

as a result of the release of cortical oocyte granules, which contain lysosomal enzymes: (1) oocyte membrane becomes impenetrable to other sperm, (2) zona pellucida alters its structure and composition to prevent sperm binding and penetration these reactions prevent polyspermy (penetration of more than one spermatozoon into oocyte)

Question 35

Egg Response: Resumption of the Second Meiotic Division

Answer 35

oocyte finishes its second meiotic division immed. after entry of spermatozoon product: 2 daughter cells its chromosomes (22+X) arrange themselves in a vesicular nucleus (female pronucleus)

Question 36

Egg Response: Metabolic Activation of the Egg

Answer 36

spermatozoon moves forward until it lies close to the female pronucleus nucleus becomes swollen and forms the male pronucleus, the tail detaches and degenerates male and female pronuclei are: indistinguishable and lose their nuclear envelopes; both haploid and replicate its DNA chromosome organize in the spindle in preparation for normal mitotic division

Question 37

Results of Fertilization

Answer 37

Restoration of the Diploid Number of Chromosomes Determination of the Sex of the New Individual Initiation of Cleavage

Question 38

Zygote

Answer 38

fertilized ovum

Question 39

Results of Fertilization: Restoration of the Diploid Number of Chromosomes

Answer 39

half from father, half from mother zygote contains new combination of chromosomes different from both parents

Question 40

Results of Fertilization: Determination of the Sex of the New Individual

Answer 40

X-carrying sperm produces female (XX) embryo; Y-carrying sperm produces a male (XY) embryo chromosomal sex of embryo is determined at fertilization

Question 41

Results of Fertilization: Initiation of Cleavage

Answer 41

without fertilization, oocyte usually degenerates 24 hrs aft ovulation