Gondal development

Question 1

Where is the gonad located in the developing fetus at ~5 weeks?

Answer 1

Around the medial border of the mesonephros

Question 1

Where is the urogenital ridge?

Answer 1

The intermediate mesoderm

The mesonephros and the gonad compose the urogenital ridge

Question 2

When does the urogenital ridge begin to develop?

Answer 2

~4.5 weeks

Question 3

What cells populate the gonadal ridge?

Answer 3

Primordial germ cells that situate themselves on the posterior wall of the yolk sack until week six. At week six, the promordial germ cells migrate across the dorsal mesentery into gonadal tissue.

These cells stimulate the ridge to become either an ovary or a teste

Question 4

What can give rise to sacrococcygeal teratomas?

Answer 4

When the primordial germ cells fail to migrate into the gonadal tissue, residing in the posterior yolk sac.

Question 5

After the primordial germ cells migrate into the gonadal tissue, the intermediate mesoderm begins to proliferate surrounding each primordial germ cell with ______ ?

Answer 5

Epithelial tissue

These cells nourish the primordial germ cells as they differentiate

Question 6

Tunica albuginea

Answer 6

Fibrous tissue

Question 6

What cell line do sertoli cells arise from?

Answer 6

The epithelium of the gland

Sertoli cells: derived from epithelium: nurse cells for sperm + produce antimullerian hormone (AMH; also called mullerian inhibiting substance, MIS)

Question 7

Leydig cells

Answer 7

Interstitial cells (of Leydig): derived from mesenchyme of genital ridge: testosterone (mesonephric ducts, tubules, etc; dihydrotestosterone, external genitalia

Leydig cells act on mesonephric tubules to form a structure that conducts the sperm at pubert

Question 8

What does the main mesonephric duct form into?

Answer 8

The ductus deferens and epididymis

Question 9

What are the mesodermal cells that surround the primary oocyte?

Answer 9

Follicular cells, nourish the oocyte

They oocyte surrounded by folicular cells is called a primordial follicle

Question 10

Why is the mesonephric system not maintained in the female?

Answer 10

Without interstitial Leydig cells, testosterone is not produced. The paramesonephric duct remains because there are not sertoli cells secreting Mullerian inhibiting substance (MIS).

Question 11

What do the paramesonephric ducts form?

Answer 11

The uterine tubes and the uterus and the upper portion of the vagina

The lower end of the paramesonephric ducts from the uterus

Question 12

What connects the two paramesonephric tubules?

Answer 12

The broad ligament of the uterus

Question 13

Where does the lower portion of the vagina arise?

Answer 13

An out-pocketing of the urogenital sinus

Therefore, lower end comes from endoderm and upper portion (along with uterus and fallopian tubes) are derived from intermediate mesoderm

Question 14

Uterine abnormalities

Answer 14

Question 15

Difference between male and female genetic signaling

Answer 15

Question 16

Difference between male and female gonadal development

Answer 16

Question 17

What hormone regulates the development of male external genetalia?

Answer 17

The conversion of testosterone to dihydrotestosterone

Question 18

Signals for sexual differentiation

Answer 18

Question 19

Androgen Insensitivity Syndrome (AIS):

Answer 19

Males that lack androgen receptors or fail to respond to receptor-dihydrotestosterone complexes: Genitalia fail to develop as male and a vagina may be present, but poorly developed

Question 20

Congenital Adrenal Hyperplasia (CAH):

Answer 20

Most common cause of ambiguous genitalia: Females may have an enlarged clitoris and partial fusion of the labia majora.

Question 21

What pulls the testes down into the scrotal region?

Answer 21

The gubernaculum

Stimulated by the presence of dihydrotestosterone