Gametogenesis

Question 1

What are the functions of the ovaries?

Answer 1

Produce ova
Secrete estrogen and progesterone which are responsible for the development of the secondary sexual characters and regulation of pregnancy

Question 2

What are the components of the uterine tube?

Answer 2

Infundibulum (pick the ova), ampulla (site of fertilization), isthmus and interstitial part

Question 3

What are the layers of the uterus?

Answer 3

External to internal:
1. Perimetrium - purple
2. Myometrium - green
3. Endometrium - blue

Question 4

What is the perimetrium?

Answer 4

External covering of peritoneum

Question 5

Myometrium

Answer 5

Thick smooth muscle layer

Question 6

Endometrium

Answer 6

Internal lining of mucosal layer

Question 7

Layers of the endometrium?

Answer 7

Basal layer
Functional layer

Question 8

Functions of the basal layer

Answer 8

Contains the ends of the uterine glands
Doesn’t shed during menstruation
Regenerates the functional layer

Question 9

Functions of the functional layer

Answer 9

Disintegrates & sheds at menstruation and after delivery

Question 10

What is gametogenesis?

Answer 10

Process of formation sperms (spermatogenesis) in males or ova (oogenesis) in females

Question 11

What is spermatogenesis?

Answer 11

Definition: Transformation of spermatogonia into sperm
Site: Occurs in seminiferous tubules of testis
Onset: Begins at puberty and continues throughout life

Question 12

How long does spermatogenesis take to occur?

Answer 12

60 days in seminiferous tubules

Question 13

How long do sperm last in female genital tract?

Answer 13

48 hours

Question 14

What is 1 and its function?

Answer 14

Testis
Produce sperm and secrete testosterone

Question 15

What is 2 and its function?

Answer 15

Epididymis
Stores the sperm

Question 16

What is 3 and its function?

Answer 16

Vas deferens
Transports the sperm before ejaculation

Question 17

What are 4 and 6 and their functions?

Answer 17

4 = Seminal vesicle
6 = Prostate
Secrete seminal alkaline fluid that nourishes sperm

Question 18

What is 5 and its function?

Answer 18

Ejaculatory duct
Transfer the sperm into urethra

Question 19

What is 7 and its function?

Answer 19

Bulbourethral glands
Secrete clear fluid that washes the urethra just before ejaculation

Question 20

What are the stages of spermatogenesis?

Answer 20

4 stages of spermatogenesis:
1. Proliferation
2. Growth
3. Maturation
4. Transformation

Question 21

What is proliferation (spermatogenesis)?

Answer 21

Increase in number of spermatogonia
Spermatogonia (44 + XY) divide by mitosis into daughter spermatogonia which also contain (44 +XY)

Question 22

What is growth (spermatogenesis)?

Answer 22

Increase size of spermatogonia
The daughter spermatogonia enlarge to form primary spermatocytes, which have (44 + XY)

Question 23

Stages of maturation phase (spermatogenesis)

Answer 23

First maturation division
Second maturation division

Question 24

First maturation division (spermatogenesis)

Answer 24

Each primary spermatocyte produces 2 secondary spermatocytes, each contains (22 + X OR 22 + Y) of double stranded chromosomes

Question 25

Second maturation division (spermatogenesis)

Answer 25

Each secondary spermatocyte produces 2 spermatids, each contains (22 + X OR 22 + Y) of single stranded chromosomes

Question 26

What is transformation (spermatogenesis)?

Answer 26

Spermatids transformed to mature sperm 1. Nucleus condenses 2. Acrosome (sac of enzymes) forms 3. Most of the cytoplasm is shed 4. Flagellum appears

Question 27

What are the parts of the mature sperm?

Answer 27

**Head** composed of: * Nucleus * Acrosomal cap: Enzymes that facilitate penetration of secondary oocyte **Neck**: Junction between head and tail **Tail**: Responsible for motility. Composed of: * *Middle piece*: Contains mitochondria * *Principal piece* * *End piece*

Question 28

Normal sperm count

Answer 28

Volume of ejaculate = 2-6 ml Ejaculate contains 200-600 million sperm **~100 million sperm/ml**

Question 29

What makes up the ejaculate?

Answer 29

Sperm = 5% Secretions from seminal glands = 60% Secretions from the prostate = 30%

Question 30

How do sperm move through the female reproductive system?

Answer 30

Slowly in acidic vaginal environment Rapidly in alkaline uterine environment ~200 sperm reach fertilization site ## Footnote Most sperm degenrate during passage through female genital tract

Question 31

What is azoospermia?

Answer 31

Absence of living sperms in the semen

Question 32

What is oligospermia?

Answer 32

<10 million sperm/ml = sterile Immotile & abnormal shaped sperms may cause oligospermia

Question 33

How many sperm should be motile for potential fertility?

Answer 33

At least 40% of sperm should be motile after 2 hours for potential fertility

Question 34

What is a vasectomy?

Answer 34

Trans-scrotal incision of vas deferens Most effective method of male contraception No sperms in the ejaculate, but seminal fluid vole is the same as before

Question 35

What is oogenesis?

Answer 35

Definition: Transformation of oogonia into oocytes Site: Occurs in the ovaries Onset: Starts during the fetal period. Reactivated at puberty. Continues until menopause (45-55 years)

Question 36

What are the stages of oogenesis?

Answer 36

**Prenatal events** 1. Proliferation 2. Growth 3. Maturation: *First maturation division* **Postnatal events** 1. Maturation: *Completion of first maturation division* 2. Maturation: *Second maturation division*

Question 37

What is proliferation (oogenesis)?

Answer 37

Oogonia proliferate by mitosis forming daughter oogonia (44 + XX)

Question 38

What is growth (oogenesis)?

Answer 38

Daughter oogonia enlarge to form primary oocytes (44 + XX)

Question 39

First maturation division (prenatal oogenesis)

Answer 39

Primary oocyte go through interphase & prophase At birth, all primary oocytes have completed preparation for first meiotic division They remain in prophase 1 until puberty

Question 40

First maturation division (postnatal ooegenesis)

Answer 40

Occurs at puberty ~Once every month in either ovary Cytoplasmic division is unequal (large amount in secondary oocyte) Each primary oocyte gives rise secondary oocyte & 1st polar body (22 + X) each

Question 40

First maturation division (postnatal oogenesis)

Answer 40

Occurs at puberty ~Once every month in either ovary Cytoplasmic division is unequal (large amount in secondary oocyte) Each primary oocyte gives rise secondary oocyte & 1st polar body (22 + X) each ## Footnote Polar body is discarded If the first polar body doesn't degenerate, it divides into 2 polar bodies each of them has (22 + X)

Question 41

Second maturation division (oogenesis)

Answer 41

Occurs in the uterine tube **if fertilization occurs** The 2ry oocyte produces * Mature ovum (22 + X) = fertilized 2ry oocyte * 2nd polar body (22 + X)

Question 42

Layers of the secondary oocyte

Answer 42

**Zona pellucida**: Non cellular covering of glycoprotein **Corona radiata**: Layer of follicular cells **Peri-vitelline space** (blue region): Space between zona pellucida & oocyte (red region) cell membrane

Question 43

What are the potential results of non-disjunction during meiosis II?

Answer 43

Three possible abnormal gametes ## Footnote Cell without any chromosomes is not considered a gamete