Human Embryonic development

Question 1

Which time is baby very sensitive?

Answer 1

4th,5th week in 1st trimester

Question 2

What is gametogenesis?

Answer 2

Production of male and female gametes from primordial germ cells

Question 3

When does spermatogenesis start?

Answer 3

Puberty

Question 4

Where does spermatogenesis occur?

Answer 4

In seminiferous tubules of testes

Question 5

When does oogenesis occur?

Answer 5

From fetal life in female

Question 6

Where does oogenesis occur?

Answer 6

In ovary

Question 7

What is a stem cell?

Answer 7

Undifferentiated cell that has ability to form specialised cell types

Question 8

Pluripotent cell

Answer 8

Ability to form all mature cell types in body except placental and extraembryonic cells - cannot form whole organism

Question 9

Multipotent cells

Answer 9

Ability to form more than one closely related mature cell types in body but not as varied as pluripotent cells e.g. cord blood/bone marrow stem cell form erythrocyte, leucocyte, platelet (blood related cells)

Question 10

Totipotent cells

Answer 10

Ability to form all different cell types in body including placental and extraembryonic membrane cells- can form whole organism

Question 11

Fertilisation meaning

Answer 11

Process by which male and female gametes fuse to form zygote

Question 12

Where does fertilisation occur?

Answer 12

Occur at ampullary region of uterine tubule (oviduct)

Question 13

What are the phases of fertilisation?

Answer 13

Penetration of corona radiata
Penetration of zona pellucida
Fusion of oocyte+sperm cell membranes

Question 14

What is released to stop other sperm from binding?

Answer 14

The zona pellucida releases Ca granules to prevent other sperm from binding

Question 15

What is capacitation?

Answer 15

physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg

Question 16

What is the acrosome reaction?

Answer 16

Leads to release of enzymes needed to penetrate zona pellucida
Induced by zona proteins following sperm binding to zona pellucida

Question 17

The sperms contact with plasma membrane of oocyte leads to release of what?

Answer 17

Lysosomal enzymes from cortical granules in plasma membrane

Changes permeability of zona pellucida, means no other sperm can bind to egg

Question 18

What is cleavage of zygote?

Answer 18

Repeated series of rapid mitotic cell divisions of the large zygote

From zygote to blastomere

Cleavage transforms the zygote into sold ball of cells=morula

Question 19

What is the main purpose of cleavage?

Answer 19

To go from zygote to morula

Question 20

What is a morula?

Answer 20

Solid ball of 12-16 cells following cleavage

Question 21

What is a blastocyst?

Answer 21

Stage when morula develops a inner cell mas enclosed by trophoblast

Question 22

What is parthenogenesis?

Answer 22

Process where unfertilised egg develops into new individual

Question 23

The blastocyst then develops into what?

Outer + inner layer names

Answer 23

Bilaminar germ disk:
outer layer= epiblast
inner layer= hypoblast

Question 24

What is the primitive streak?

Answer 24

Thickened midline structure at caudal end of epiblast of bilaminar germ disc- form on day 15

Question 25

What does primitive streak mark process of/

Answer 25

Gastrulation

Question 26

What is gastrulation?

Answer 26

Process of epiblast cell movement through primitive streak- turn bilaminar to trilaminar germ disc

Question 27

Trilaminar germ disc layers

Answer 27

Ectoderm
Mesoderm
Endoderm

Question 28

How can caudal dysplasia occur?

Answer 28

From errors in gastrolutation