Kuehn - Gamete Development/Fertilization

Question 1

<p>How is an oocyte transported to the ampulla?</p>

Answer 1

<p>after rupturing the outer epithelium of the ovary, enters peritoneal cavity, cumulus oophorus is hooked by cilia and pulled into infundibulum, via peristalsis is then pulled into ampulla</p>

Question 2

<p>How long can an oocyte remain in the ampulla?</p>

Answer 2

<p>12-24hrs</p>

Question 3

<p>How do sperm enter the ampulla after being deposited in birth canal?</p>

Answer 3

<p>combination of uterine peristaltic movements and sperms own chemotaxis(motility) towards oocyte</p>

Question 4

<p>What part of the oocyte degrades in the ampulla? </p>

Answer 4

<p>the cumulus oophorus degrades into corona radiata</p>

Question 5

<p>When does fertilization begin?</p>

Answer 5

<p>sperm reaches corona radiata of oocyte, passes through and attaches to Zona Pellucida</p>

Question 6

<p>What glycoproteins help the sperm to bind to Zona Pellucida?</p>

Answer 6

<p>ZP3</p>

Question 7

<p>What does the sperm release from its acrosome?</p>

Answer 7

<p>enzymes that digest Zona Pellucida</p>

Question 8

<p>What happens once the sperm has penetrated Zona Pellucida?</p>

Answer 8

<p>fusion of sperm and oocyte membranes occurs</p>

Question 9

<p>What makes Zona penetration by a second sperm unlikely?</p>

Answer 9

<p>when zona is penetrated there is a release of cortical granules from oocyte preventing a second intruder (Ca++ mediated)</p>

Question 10

<p>What occurs in order for pronuclei to fuse into a single nucleus?</p>

Answer 10

<p>oocyte completes second meiotic division = female pronucleus
sperm nucleus becomes male pronucleus</p>

Question 11

<p>The fused pronuclei are now technically what?</p>

Answer 11

<p>a zygote</p>

Question 12

<p>What is the acrosome of a sperm?</p>

Answer 12

<p>the head which contains digestive enzymes that aide in oocyte fertilization</p>

Question 13

<p>What contains the sperms haploid DNA (N) in condensed form?</p>

Answer 13

<p>the nucleus within the head</p>

Question 14

<p>What contains the mitochondria of the sperm?</p>

Answer 14

<p>the Mid-piece</p>

Question 15

<p>What does the mitochondria do for the sperm?</p>

Answer 15

<p>powers the flagellum for motility</p>

Question 16

<p>What part of the sperm contains microtubules for motility? </p>

Answer 16

<p>the tail</p>

Question 17

<p>What cell does spermatogenesis begin with and they only divide by which method?</p>

Answer 17

<p>begins with stem cell - Type Ad spermatogonium

| ALL spermatogonia divide by mitosis</p>

Question 18

<p>What is the product of Type Ad spermatogonium division?</p>

Answer 18

<p>1 - Type Ad spermatogonium

| 1 - Type Ap spermatogonium</p>

Question 19

<p> Type Ap spermatogonium further divide by mitosis and differentiate into what?</p>

Answer 19

<p>Type B spermatogonia (terminal differentiation) which divide by mitosis into primary spermatocytes</p>

Question 20

<p>How do the primary spermatocytes form into secondary spermatocytes?</p>

Answer 20

<p>they divide by meiosis in Division I (reduction division)</p>

Question 21

<p>What is formed when the secondary spermatocytes undergo Division II of meiosis?</p>

Answer 21

<p>Spermatids (round cells) are formed! (genetically mature gametes - not physically mature)</p>

Question 22

<p>What occurs after morphological differentiation of spermatids (spermiogenesis)?</p>

Answer 22

<p>nucleus condenses and Normal sperm forms = mature Spermatozoan</p>

Question 23

<p>What triggers the spermatids to mature?</p>

Answer 23

<p>a response to Bcl2-family gene products</p>

Question 24

<p>What are follicles?</p>

Answer 24

<p>they contain oocytes, throughout their development, and follicular cells</p>

Question 25

<p>When do oogonia complete differentiation into primary oocytes?</p>

Answer 25

<p>oogonia is only found in fetus and completes differentiation by birth</p>

Question 26

<p>When does the primary oocyte begin to form a secondary oocyte?</p>

Answer 26

<p>it remains in Prophase of Division I until a signal initiates further development</p>

Question 27

<p>Where are the secondary oocytes found? </p>

Answer 27

<p>only in final stage of Graffian follicle, just before ovulation (1 day or so)</p>

Question 28

<p>What is a primordial follicle?</p>

Answer 28

<p>only one thin layer of follicular cells</p>

Question 29

<p>What is a primary follicle?</p>

Answer 29

<p>cuboidal layer of follicular cells</p>

Question 30

<p>What is a secondary follicle?</p>

Answer 30

<p>a growing follicle with primary oocyte</p>

Question 31

<p>What is a mature/antral/graffian follicle?</p>

Answer 31

<p>it contains antrum and primary/secondary oocyte</p>

Question 32

<p>After fertilization what occurs in the zygote?</p>

Answer 32

<p>cells rapidly manufacture new proteins(microtubules, histones, and enzymes) and the DNA replicates</p>

Question 33

<p>When does the zygote move into the uterine tube?</p>

Answer 33

<p>after about 30 hours and undergoes first cleavage into two blastomeres</p>

Question 34

What happens to the blastomeres after first cleavage?

Answer 34

cells synchronously divide until LAST stage of 8 cells and are surrounded by Zona Pellucida

Question 35

What is the ball of 12-32 cells still bound in Zona Pellucida called and how long since fertilization is it?

Answer 35

MORULA and it is now 3 days after fertilization

Question 36

What happens to the cells in the morula at ~ day 4 of fertilization?

Answer 36

cells shrink and migrate to the edge leaving a cavity in the center (blastocyst cavity) - called early blastocyst

Question 37

Describe the parts of the early blastocyst?

Answer 37

whole surrounded by zona pellucida, trophoblast cells surround embryoblast/epiblast (inner cell mass) and hypoblast

Question 38

What happens in humans on day 5 after fertilization?

Answer 38

zona pellucida breaks open and blastocyst squeezes out, exposed receptors on trophoblast will attach to uterus

Question 39

Timing is everything! What can happen if timing of blastocyst attachment is wrong?

Answer 39

blastocyst will implant on any surface, errors in timing result in extopic attachment (ovary, mesenteries, uterine tube)

Question 40

What does the blastocystic cavity become?

Answer 40

it becomes the exocelomic cavity

Question 41

What does the exocelomic cavity become?

Answer 41

becomes the yolk sac cavity

Question 42

what becomes the bilaminar embryonic disc?

Answer 42

the epiblast and hypoblast together make up the embryonic disc