Lec: 64 Early Embryogenesis Flashcards Preview

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Flashcards in Lec: 64 Early Embryogenesis Deck (13):
1

Embryo

until the end of the 8th week

2

Zygote

2-cell stage to morula

3

Morula

day 3

4

Blastocyst

days 4 - 6

5

Fetus

week 9 to birth

6

Ovulation

- Completes first meiotic division.
- Arrests at metaphase of meiosis II.
- Oocyte has a haploid number (1n) of chromosomes but is diploid in DNA content (2d).
- It is 23, X.

7

Uterine Tube Mucosa

-Peg cells secrete nutritive material for ovum.
-Ciliated cells move fluid down the tube.

8

Ovum viable in female reproductive tract

24 hours

9

Sperm

• Consists of a nucleus and a tail
• Contains a haploid number (1n) of chromosomes and is haploid in DNA content (1d). 23, X or 23, Y

10

Sperm viability:

24-48 hrs

11

Epididymis

Sperm:
- Gain motility
- Storage

12

Fertilization

From contact to mingling of genetic material
Takes 24 hours
1. Penetration of Corona Radiata
2. Penetration of Zona Pellucida
3.Ovum Sperm Membrane Fusion
4. Male Pronucleus forms
5. Pronuclei replicate their DNA.
6. Pronuclear membranes degenerate
7. Chromosomes line up for mitosis and first cleavage

13

Notochord

•Cord of cells that is located between the ectoderm and endoderm: from primitive node/pit to the region of the oropharyngeal membrane (consists of two layers: ectoderm and endoderm)
•Functions as the primary signaling center in the early embryo
•Induces the overlying ectoderm to thicken and form the neural plate (primordium of CNS)

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