The Beginning of Human Development

Question 1

Human Development

Answer 1

Continuous process that begins when an oocyte is fertilized by a sperm. Cell division, migration, apoptosis, differentiation, growth, cell rearrangement transform the fertilized oocyte, a totipotent zygote, into a multicellular human being

Question 2

Human Embryology

Answer 2

The study of prenatal development

Question 3

Gestation period

Answer 3

280 days from onset of last menstruation or 266 days from fertilization

Question 4

Prenatal Periods

Answer 4

Pre-embryonic: fertilization - 2 weeks
Embryonic: 3-8 weeks
Fetal: 9 weeks-birth

Question 5

Fertilization results in:

Answer 5

1. oocyte completing meiosis II
2. restoration of diploid chromosome number in zygote
3. species variation
4. determination of genetic sex
5. initiation of cleavage of zygote

Question 6

Gametogenesis

Answer 6

Process of formation and development of specialized generative cells (gametes)

Question 7

Spermatogenesis

Answer 7

gamete maturation in males

Question 8

Oogenesis

Answer 8

gamete maturation in females

Question 9

Spermatogonium

Answer 9

Stem cell

Question 10

Antrum

Answer 10

Characteristic of a secondary oocyte

Question 11

Zona Pellucida

Answer 11

Shell-like structure surrounding an oocyte

- glycoprotein that provides protection

Question 12

Corona radiata

Answer 12

Follicular cells that spermatid must fight its way through, loses some cytoplasmic material on the way

Question 13

Mitochondrial sheath

Answer 13

powers that flagellar movement via. ATP synthesis

Question 14

Ovarian cycle

Answer 14

FSH & LH produce cyclic changes in the ovaries including the growth of follicles, ovulation, and corpus luteum formation

Question 15

FSH

Answer 15

Follicle stimulating hormone

Question 16

LH

Answer 16

Luteinizing hormone

Question 17

HPO

Answer 17

Hypotallamus, pituitary gland, ovaries
- Hypothallamus releases gonadotropin-releasing hormone that acts on pituitary gland, which releases gonadotropic hormones (LH & FSH)

Question 18

Primary follicle

Answer 18

Activated by FSH, starts to divide rapidly

Question 19

Theca Folliculi

Answer 19

follicle developed around the secondary oocyte, build-up of fluid inside the theca folliculi results in the release of the oocyte (ovulation)

Question 20

Corpus Luteum

Answer 20

produces progesterone and estrogen, activated by LH

the theca folliculi transforms to the corpus luteum following ovulation

Question 21

Estrogen

Answer 21

Released by the corpus luteum, fuses through the plasma membrane and binds to an estrogen receptor. Activated ER transfers transcription factor to the nucleus, results in rapid proliferation

Question 22

Sperm lytic enzymes

Answer 22

Hylurinidase, acrosin

Question 23

What occurs upon lack of fertilization

Answer 23

Corpus luteum degenerates, cutting the supply of progesterone and estrogen, resulting in the halting of proliferation. Lining will degenerate, rupturing blood vessels

Question 24

What occurs upon fertilization

Answer 24

Sperm releases lytic enzymes to make it past the zona pellucida, once past the pellucida becomes impermeable.

Question 25

First phase

Answer 25

two haploid pronuclei - ootid

Question 26

Second phase

Answer 26

one diploid nucleus - zygote

Question 27

When does the first cell division occur

Answer 27

30 hours following fertilization

Question 28

12 - 34 hours

Answer 28

Zona pellucida is still present, results in the shrinking of cells as they divide. Uterine fluid has digestive enzymes that will slowly degrade the zona pellucida, cells push to one side and surround the zona pellucida and fluid seeps n and creates an inner cavity (embryonic hole)

Question 29

When does the blastocyst form

Answer 29

4 days following fertilization

Question 30

What happens 4 days after fertilization

Answer 30

Morula enters the uterus. Fluid-filled space (blastocystic cavity) appears. Fluid passes from the uterine cavity through the zona pellucida to form the cavity. As fluid increases the cavity, it forms 2 parts - tropho and embryoblast

Question 31

Blast Cells

Answer 31

Cells that have the potential to form something

Question 32

What happens 6 days after fertilization

Answer 32

Blastocyst attaches to the endometrial epithelium, as soon as it attached the trophoblast proliferates rapidly and differentiates into the cyto and syncitiotrophoblast

Question 33

Cytotrophoblast

Answer 33

Inner, mono-nuclear layer of the trophoblast

Question 34

Syncitiotrophoblast

Answer 34

Outer, multi-nucleated photoplasmic mass in which no cell boundaries can be observed