Unit 1, Part 2 - Embryology

After fertilization occurs, cell divide to form a _______.

Blastocyst

What does the blastocyst form into?

Embryotic disc

The embryotic disc divides into what 3 layers?

1. Ectoderm

2. Mesoderm

3. Endoderm

What development takes place in the Ectoderm (outer) layer consist of?

Neuro

What development takes place in the Mesoderm (middle) layer consist of?

• Heart / Circulatory system

• Musculoskeletal system

• Kidneys & Reproductive system

What development takes place in the Endoderm (inner) layer consist of?

• Lungs

• GI Tract

• Urinary Bladder

In this image, the blue dotted line represents the _________ layer.

Ectoderm (outer)

In this image, the red dotted line represents the _________ layer.

Mesoderm (middle)

In this image, the yellow dotted line represents the _________ layer.

Endoderm (inner)

The male/female external genitalia have a similar appearance until week ____.

9

External organs are fully developed at week ___.

12

Clitoris develops from the …

Genital tubercle (phallus)

The labia minora develop from the …

Genital folds

The labia major develops from the …

Genital swelling

The vestibule develops from the …

Urogenital sinus

The ovary develops from the …

Urogenital ridge + primordial germ cells

Unfused portion of Mullerian ducts

Fallopian tubes

Fused portion of Mullerian ducts

Uterus, Vagina, Cervix

Urogenital sinus =

Vestibule of external genitalia

First parts of genital system to develop

Gonads

Gonads arises from parts of urogenital ridges, known as the …

Gonadal ridges

As the gonadal ridges enlarges, it frees itself from the __________ by developing a mesentery that becomes the __________.

Mesonephros, mesovarium

What does the covering of the gonadal ridges grow and form?

Primary sex cords

The primary sex cords grow into the _________ of developing gonads.

Mesenchyme

Where do germ cells originate from?

In the wall of the yolk sac

The germ cells migrate into the ________ and enter the primary sex cords to give rise to an ____.

Embryo, ova

Mature female reproductive cell?

Ova

Ovas are located in the _____.

Ovaries

Differentiation of gonads occur later in, male or females?

Females

The primary sex cords coverage to form a network of canals, known as …

Rete ovarii

The rete ovarii disappear with the _____ _____ ______.

Primary sex cords

Primary sex cords / oogoniums enlarge to form ______ ______.

Primary oocytes

Oocytes =

Ovarian cells

During female development, all ova (primary follicles) are formed to last a women’s whole fertile period.

True

The process of _____ __ _____ remains in arrested state until puberty.

Meiosis of oocytes