Devo Block 1 Week 5: Development Of The Reproductive System 10A

Front 1

What three things do you need in order to develop a reproductive system?

Back 1

Gonads, Duct system, External genitalia

Front 2

In the four week embryo, study where the indifferent gonad forms in relation to the mesonephric kidney.

Back 2

It is forming at the Ventromedial aspect of the UG ridge.

Front 3

Where does the indifferent gonad form?

Back 3

Within the ventromedial aspect of the UG ridge?

Front 4

So, you have the gonads forming via epithelial proliferation at the ventromedial aspect of the UG ridge. How do the germ cells get to this area?

Back 4

The germ cells arise in hindgut and travel via the dorsal mesentary to populate the gonads.

Front 5

Where do supporting cells of the gonads derive from?

Back 5

The epithelial ceolom

Front 6

What are the cells in males and different in females, that produce sex hormones?

Back 6

Leydig cells in Males and Thecal cells in Female.

Front 7

What are the precursor cells of the Leydig/Thecal cells?

Back 7

UG Mesenchyme within the UG ridge.

Front 8

What is the role of the Gubernaculum in both the male and female?

Back 8

It guides the gonads to their definitive location.

Front 9

There are two duct systems that develop during the indifferent stage. What are they?

Back 9

Mesonephric Duct and the Paramesonephric Duct

Front 10

Initially the mesonephric duct is essentially the same as the kidney. Then the paramesonephric duct appears adjacent to each mesonephric duct. What happens to both of them over time?

Back 10

The mesenephric ducts remain separated and serve the gonads. The paramesonephric duct becomes the vagina or penis.

Front 11

At 4-6 weeks, the sexually undifferentiated embryo has? (three points)

Back 11

1. a pair of undifferentiated gonads
2. two sets of ducts (para/mesophrenic)
3. Elevations and folds around the opening of the UG sinus.

Front 12

Which cells are male gonads and which are female?

Back 12

The two on the L are males - notice the strands that ultimately open up during puberty.
The two on the R are female - notice the round cells - oocytes?

Front 13

What is cryptorchidism?

Back 13

It is failure of testis to descend into scrotum and remain in the abdomen. In females, failure of ovaries to descend into pelvis.

Front 14

In the female, the gubernaculum ultimately becomes:

Back 14

The ligament of the ovary. Connecting the ovary to the uterus.

Front 15

In males, the derivatives of the mesonephric ducts are (4):
What one structure comes from the mesonephric tubule?

Back 15

1. Duct of epididymis
2. Ductus (vas) deferens
3. Ejaculatory duct
4. Seminal vesicle
--
Efferent ductules come from the tubules.

Front 16

Note that in addition to the duct system, the presence of androgen also promotes the development of what?

Back 16

The prostate gland

Front 17

Note that the mesonephric ducts are dependent on what hormone? What does this mean in the male vs female?

Back 17

Dependent on Androgen. This means the ducts develop further into males. In females, the mesonephric ducts atrophy

Front 18

What is MIS and what affect does it have on the male? What is it produced by?

Back 18

Mullerian Inhibitory Substance stimulates the regression of the paramesonephric ducts. Produced by Sertoli cells.

Front 19

In female, absence of MIS promotes growth and differentiation of the:

Back 19

Paramesonephric ducts.

Front 20

In female, what is the fate of the paramesonephric ducts?

Back 20

They become oviduct.

Front 21

Note: the paramesonephric ducts & pelvic part of the UG sinus interact with each other to form the vagina.

Back 21

a

Front 22

During the indifferent stage, the interior of the definitive UG sinus is remodeled. For the pelvic portion, what does the male and female remodel to? What about the phallic portion.

Back 22

Pelvic Portion:
Male = distal prostatic & membranous urethra
Female = part of vagina
__________________
Phallic Portion:
Male = penile urethra
Female = vestibule

Front 23

Note that the gonad is bipotential. If SRY is positive, gonad becomes ? . If SRY is negative, gonad becomes ? .

Back 23

Positve SRY = male testes
Negative SRY = female ovary

Front 24

Re internal genitalia differentiation, the male ducts are called ? and include? The females ducts are called ? and include ?

Back 24

Male = Wolffian: Epididymis, vas deferens, seminal vescles
Female = Mullerian: uterus, tubes, upper vagina

Front 25

Interestingly, if there are problems with the genitalia, you always have to check out which system bc they are associated.

Back 25

Renal

Front 26

What hormone is responsible for causing regression of Mullerian ducts? Which sex does this lead to?

Back 26

AMH - anti-mullerian hormone. Brings about males.

Front 27

If there's ambiguous genitalia with a male karyotype, there's not enough testosterone. Why might this be? (he gave 4 examples)

Back 27

Testosterone:
1. Synthesis (lack thereof)
2. Receptor defects
3. End organ conversion
4. Anti-mullerian hormone deficiency (internal)

Front 28

If there's ambiguous genitalia with a female karyotype, there's too much androgen. Why might this be? (he gave 2 examples)

Back 28

1. High intake or production
2. Aromatase deficiency

Front 29

Clinically, how is male or female defined? (3 points for each)

Back 29

Male:
1. Y-chrom
2. No uterus
3. Testes
Female:
1. No Y chromosome
2. Uterus
3. No testes

Front 30

For the first case a 17yo girl with now breast development or pubic hair. Her karyotype is XY but lost testes and not testosterone. Since she IDs as a female, she'll require estrogen for development and protection of bones.

Back 30

a

Front 31

For case 2 - female with adequate breast development. She is producing estrogen and not much testosterone. She's XY and high testosterone but there's a receptor problem. (see back for treatment)

Back 31

She has Complete Androgen Insensitivity. Here testes are producing testosterone that is being aromatized into estrogen. However, you want to remove them bc they might become malignant. You do this after pubertal development. After you remove testes you must estrogen treat her (if she had a uterus, you'd have to give her progesterone to counter estrogen - it might change uterus tissue into tumor).

Front 32

For case 3 with the XX girl producing too much androgen, what is the physiological problem with her? What's the clue?

Back 32

Deficiency of 21-hydroxylase. Clue is she didn't have high blood pressure.

Front 33

What is the treatment for the XX girl overproducing androgen?

Back 33

She needs cortisol to shut down stimulation of adrenal gland.

Front 34

What hormone is responsible for external genitalia?

Back 34

Dihydrotestosterone

Front 35

Which of the following is NOT a characteristic of complete androgen insensitivity in a 28 yo phenotypic female?

Back 35

Normal adult female testosterone level.

Front 36

Deficiency of 17Alpha-hydroxylase is: (genetic)

Back 36

Autosomal recessive

Front 37

Mullerian-inhibiting substance is secreted by:

Back 37

Sertoli cells