A). Structure of sperm

1). Head

acromere.

2). Midpiece

3). Tail

 

B). Oocyte

1). Primary oocyte:

2). Secondary oocyte:

offspring inherit  mitochondrial DNA from their mothers.

      

 

1.  Oocyte encapsulated

corna radiata

zona pellucida

2. The sperm becomes capacitated (readied)

After ejaculation the sperm membranes become fragile

3.  It takes more than one acromere to break through the capsule

4. Connect to the sperm receptors

5. membranes merge 

III). Immediately after fertilization occurs

Fertilization occurs

sperm loses tail

secondary oocyte undergoes meiosis II

(meiosis I occurred during the female’s fetal development)

eject polar body

female pronuclei

male pronuclei

form a mitotic spindle

 produce a diploid zygote.

undergoes cleavage

trophoblast

IV). Development

Zygote:

Embryo:

Fetus:

V).  Zygote Development

Zygote formation

cleavage

4 cells

Morula

Blastocyst

differentiating into:

Inner cell mass:

Trophoblast cells:

 develop during gastrula

1). Embryonic (Disc) Germ Layers

Ectoderm

Mesoderm

Endoderm

2).  Amnion:

3). Yolk Sac:

•  part of the gut
•  early blood cells
• forms  gonads

4). Allantios:

5). Chorion:

 

A). What prevents the normal sloughing off of the uterine wall?

 

The  embryo must maintain the corpus luteum until the placenta can take over its endocrine functions.

 human chorionic gonadotropin (hCG)

 acts like luteinizing hormone.

 

B). Formation

Trophoblast

Chorion & chronic villi form:

(Amnion forms around the embryo)

new vessels form, which extend to the embryo

 The endometrium the villi forms the placenta.

Fetal side is flat and smooth and slick

     Maternal side is bumpy

Blood cells arise in the yolk sac

spaces appear in mesoderm

(middle germ layer)

become network

heart, blood vessels, etc.

by 3.5 weeks heart is formed and beating

    Umbilical Vein transport oxygen rich blood

    blood enters the liver and the ductus venous

    It is than shunted from the right atrium to the left atrium through the foramen ovale

    Blood in the descending aorta branches off into the umbilical artery to the placenta