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Flashcards in Lect 1 Deck (44):
0

What is embryology?

The study of prenatal development

Normal human structure/variation and prenatal care

1

What stages make up prenatal?

Day one - end of week 2 : pre embryonic
Week 3- end of week 8: embryonic
Week 9- birth ( week 38) : fetal

2

What is the main even in pre embryonic stage?

Implantation of the zygote into the uterine wall

3

What are the main events in embryonic stages

The creation of germ layers and organogenesis

4

What occurs during the fetal stage?

Growth and maturation of organ systems

5

What's the difference between gestational age and fertilisation age?

Gestational is obstetric, starts from 1st day of last normal menstral period, where as fertilisation would have occurred sometime prior to this event ( about 2 weeks -14 days)

6

How long is the first trimester?

13 weeks

7

When does almost 50% of spontaneous abortions happen?

The pre embryonic period ( day 1 - end of week 2)

8

Most birth defects appear in what stage?

Embryonic period , when organogenesis is occurring

9

Define conceptus

All structures that are derived from the fertilised egg( placenta, anything that is not normally in the mom before fertilisation

10

What is induction?

Initiation of embryonic cell migration

11

What is gametogenesis?

Gamete production and preparation for fertilisation - occurs through mitosis, meiosis, and maturation

12

What state is the cell in before DNA replication occurs?

You have 1 diploid ( mom and dad) cell, 2n: 46 single chromatid chromosomes (23 mom: 23 dad) ... This is normal

13

What cell type do you have after DNA replication occurs during gametogenesis?

1 diploid cell -(mom and dad ) but doubled ..4n : 46 DOUBLE chromatid chromosomes

14

After DNA replication Is the 1st mitosis decision. What does the cells look like ?

2 HAPLOID cells, (1 for maternal material and 1 with paternal material) but each has 2n: 23 double chromatid chromosomes

15

What stage do you have 4 separate haploid cells (n:23 single chromatid chromosomes) ?

After the second mitosis decision

16

When does OOgenesis begin ?

Prenatal ,is DNA replication portion of meiosis

17

When does spermatogenesis begin?

Puberty is continuous. 86 day cycle

18

When does meiosis one occur in famale OOgenesis?

Meiosis I occurs prenatal ( like DNA replication) and completes during ovulation

19

When does meiosis II begin/ complete for females?

Meiosis II begins at ovulation and completes at fertilisation

20

What are the products of meiosis for males and females?

Females make 1 oocyte ( and 3 polar bodies) males make 4 spermatids that mature into sperm around 86 days

21

What are the three important factors of meiosis ?

1- forms diploid cell/ fertilisation 23 mom 23 dad single chromatid chromosomes
2- random assortment
3- variation and recombination

22

If there is a chromosomal abnormality during meiosis what can happen ?

~ 25% spontaneous abortions and ~10% major birth defects

23

What is it when chromosome pairs do not separate properly?

Nondisjunction - can cause monosomy or trisomy

24

What is trisomy 21?

Down syndrome - extra chromosome at chromosome 21

25

When you have one chromosome missing?

Turner syndrome . 45, X monosomy .. At 23 you have x but no Y

26

What causes Klinefelter syndrome?

You have an extra chromosome: 47 xxy trisomy.

27

When is the oocyte in MEIOTIC arrest?

After birth, before ovulation of the oocyte, correlation between increased wait in MEIOTIC arrest and increase risk to environmental influences.

28

What is the male reproductive pathway?

TED EU: testis, epididymis, ductus deferens, ejaculatory duct, urethra

29

What happened in the epididymis ?

Storage of sperm, sperm become motile, and released at ejaculation

30

Where does OOgenesis ocur?

I the ovary

31

What is capacitation?

7 hour conditions of sperm, removes glycoproteins coat on spermatids head

32

Where does fertilisation typically occur?

Ampulla of uterine tube

33

If more than one spam fertilises the egg it is called...

Polyspermy

34

Before fertilisation what stage is the oocyte in?

The oocyte is arrested in meiosis II until fertilisation ( meiosis I was complete at ovulation)

35

What is the "enzymatic drill"?

The acrosome reaction where the sperm drills through the zone polucida of the oocyte .

36

What does the acrosome reaction trigger?

The zone reaction, where the ZP hardens to prevent polyspermy

37

If polyspermy occurs, what can be the cause of this?

The zone reaction did not occur quick enough

38

What is the result of the some membrane fusing with the oocyte?

Completing on meiosis II

39

What are the fertilisation sequence of events?

1.) capacitation 2.) corona radiate penetration 3.) Acrosome and Zona reactions 4.) fusion and meiosis II completion 5.) zygote and sex is formed

40

What is a pro nuclei ?

A haploid

41

What percentage of couples are infertile?

15-30% reasons - insufficient sperm #, poor motility, PID, Ovulation disorders, endometriosis, cysts

42

When is the greatest risk of spontaneous abortions ?

Pre embryonic period

43

When is the greatest risk of birth defects?

Embryonic period ( week 3- end of 12)