Fertilization

Question 1

Define fertilization and its site

Answer 1

Process by which mature sperm and mature ovum meet and fuse forming the zygote

Ampullary part(lateral third) of the uterine tube

Question 2

What are the stages of fertilization

Answer 2

Spermatozoa is not able to fertilize oocyte immediately and must undergo capacitation and acrosome reaction

Question 3

Describe the spermatozoa

Answer 3

▪️Head occupied by 23 chromosomes and acrosome which partially surrounds the anterior aspect of the nucleus
▪️middle piece which contains mitochondrial sheath that provides energy for motility
▪️tail houses axoneme that has structure similar to cilia and responsible for sperm motility

Question 4

What are enzymes in the head

Answer 4

Neuraminidase, hyaluronidase, acid phosphatase, aryl sulfatase, acrosin

Question 5

Describe capacitation

Answer 5

Period of conditioning in female reproductive tract(lasts 7 hours)

glycoprotein coat and seminal plasma proteins are removed from plasma membrane that overlies acrosomal region of spermatozoa

Question 6

Describe the acrosome reaction

Answer 6

Occurs after binding of the head to the zonapellucida and is induced by zona proteins

Question 7

What are the phases of fertilization

Answer 7

1-penetration of corona radiate
2-penetration of zona pellucida
3-fusion of oocyte and sperm head cell membranes

Question 8

What is cleavage and its site

Answer 8

Series of mitotic divisions that results in increase in cells
Uterine tube medial to the ampulla

Question 9

What are the stages of cleavage

Answer 9

A)Morula stage
Zygote divides in to 2 cells (blastomeres)
16 blastomeres= morula

B)blastocyst formation
Fluid from uterine cavity penetrates through zona pellucida and forms single cavity (blastocele)
Blastocele divides blastomeres in to inner cell mass and outer cell mass

Question 10

What do the inner and outer cell masses form

Answer 10

Inner: embryo proper(embryoblast)
Outer:forms trophoblast

Question 11

Define implantation,its time,and normal site

Answer 11

Means penetration of blastocyst in to superficial layer of uterine endometrium

Time: end of first week and finishes day 11
Normal site: endometrium of the anterior or posterior wall of uterus or near the middle line

Question 12

What is the decidua and its types

Answer 12

The endometrium after implantation
1-descidua basalis 
2-decidua capsularis 
3-decidua parietalis
4-decidua marginalis

Question 13

What is the decidua basalis

Answer 13

Part of endometrium lying at base of implanted blastocyst (maternal origin of placenta)

Question 14

What is the decidua capsularis

Answer 14

Part of endometrium covering surface of implanted blastocyst

Question 15

What is the decidua parietalis

Answer 15

Part of endometrium lining the rest of the uterine cavity

Question 16

What is the decidua marginalis

Answer 16

Part of endometrium lying at the junction between decidua capsularis and parietalis

Question 17

Clinical correlation of pregnancy testing

Answer 17

Syncytiotrophoblast is responsible for hormone production
Secretes human chorionic gonadotropin
(Inc in second week)

Question 18

What is abnormal implanation

Answer 18

Implantation of blastocyst in any other place than normal site and might result in death of embryo or early abortion

Question 19

What are the abnormal sites

Answer 19

1-uterine ectopic pregnancy
a)at cornu of uterus (attachment site of uterine tube)
b)at lower uterine segment or cervix leading to placenta previa
2-extra uterine ectopic pregnancy
a)commonest sites in fallopian tube
b)ovary
c)abdominal pregnancy very rare

Question 20

What is placenta previa

Answer 20

Implantation of blastocyst in lower segment of uterus close to internal os of the cervix
So placenta will precede baby at delivery