Embryology

Question 1

______ forms in the upper thoracic to upper lumbar region. It develops from superior to inferior, and performs filtration from about ______ weeks gestation (though not all parts at once).

Answer 1

Mesonephros, 4-10

Question 2

____ takes care of filtration for the embryo < 4 weeks

Answer 2

Pronephros

Question 3

Eventually the mesonephros’ filtration function is replaced by the ____ which becomes the

Answer 3

metanephros, adult kidney.

Question 4

Eventually, around week ____ the mesonephros’ filtration function is replaced by the ____ which becomes the

Answer 4

5, metanephros, adult kidney.

Question 5

Primordial germ cells differentiate in _______ and migrate to the ______ at the ___ week

Answer 5

Neck of the yolk sac
Genital ridge
4-5th weeks

Question 6

the “indifferent stage”

Answer 6

• Before 10 weeks

- both male and female genital ducts are present

Question 7

Male duct system develops from the _______

Answer 7

Mesonephric / Wolffian Ducts

Question 8

Female duct system develops from the _____

Answer 8

Paramesonephric / Mullerian Ducts

Question 9

Mesonephric ducts form the _______ in males

Answer 9

epididymis,
ductus deferens,
efferent ducts,
ejaculatory duct

Question 10

Paramesonephric ducts form the _____ in females

Answer 10

fallopian tubes,
uterus,
upper 1/3 to 2/3 of the vagina.

Question 11

Genital duct differentiation begins

Answer 11

during 3rd month of gestation (8-9 weeks)

Question 12

Genital duct differentiation begins

Answer 12

during 3rd month of gestation (8-9 weeks)

Question 13

______ causes Wolffian (mesonephric) ducts to differentiate into male genital structures, the gonads to become testes

Answer 13

TDF (Testes determining factor)

Question 14

The testes make _______ to cause the mullerian/paramesonephric ducts to regress

Answer 14

Mullerian Inhibiting Substance

Question 15

Primary sex cords of testes containing the primordial germ cells, and are located __

Answer 15

Testes cords (spermatic cords), medulla of testes

spermatic cords are solid until puberty, when then canalize and become Seminiferous Tubules

Question 16

Spermatic cords contain what two types of cells

Answer 16

(epithelial cells&raquo_space;) Sertoli cells (“nurse” cells for sperm)

(primordial germ cells&raquo_space;) Spermatoblasts

Question 17

With puberty, spermatic cords become the

Answer 17

Seminiferous Tubules

Question 18

Cells within the seminiferous tubules which make testosterone

Answer 18

Cells of Leydig

Question 19

What if testes fail to ever develop in the fetus, or are removed from the fetus very early on?

Answer 19

Paramesonephric ducts will be uninhibited (by MIS) and will become female genetalia

Question 20

What if ovaries fail to develop or are removed in the female fetus?

Answer 20

Has no effect on fetal sexual development– still female genitalia

Question 21

What if ovaries fail to develop or are removed in the female fetus?

Answer 21

Has no effect on fetal sexual development– still female genitalia

Question 22

a common opening shared by the digestive, reproductive, and the urinary tracts.

Answer 22

Cloaca

Question 23

A ______ develops at the anterior end of the cloacal membrane/ Elongates to form the Phallus

Answer 23

genital tubercle

Question 24

Fusion of the ______ makes the scrotum.

Fusion of the ______creates the penis and the elongated urethra.

Answer 24

Labioscrotal folds

Urogenital folds

Question 25

Incomplete fusion of the ureteral folds. | Typically more distal, though proximal variations can occur.

Answer 25

Hypospadia

Question 26

The testicles descend to the level of internal inguinal ring at about which time point during gestation?

Answer 26

7th month

Question 27

The testicles descend to the level of internal inguinal ring at about which time point during gestation?

Answer 27

7th month

Question 28

Ovary cannot be defined histologically until

Answer 28

10th week

Question 29

The sex cords which become seminiferous tubules in males become what in females

Answer 29

Primordial follicles

Question 30

Each primordial follicle consists of

Answer 30

``` Oogonium (from primordial germ cells) Follicular cells (from surface epithelium, surround oogonium) ```

Question 31

About how many oogonium remain to become primary oocytes at birth

Answer 31

2 million

Question 32

by puberty about how many oocytes remain

Answer 32

500,000

Question 33

by puberty about how many oocytes remain

Answer 33

500,000

Question 34

Mesonephric ducts will form the _____ which will deliver sperm to the region of the prostate

Answer 34

Ductus Deferens

Question 35

The paramesonephric ducts fuse to form_________ in the midline and will become the ______

Answer 35

a Y-shaped uterovaginal primordium | Uterus and superior portion of vagina

Question 36

The uterine (fallopian) tubes develop from ____

Answer 36

the unfused, cranial part of the paramesonephric ducts.

Question 37

When the paramesonephric ducts fuse, the process also brings together two sides of a peritoneal fold that, when folded together, form the

Answer 37

broad ligament

Question 38

An enlargement at the end of the____ induces the formation of paired endodermal outgrowths called ____

Answer 38

urogenital sinus | sinovaginal bulbs.

Question 39

The sinovaginal bulbs fuse to form a

Answer 39

vaginal plate.

Question 40

The two sets of tissue which fuse and canalize to form the vagina

Answer 40

urigenital sinus | sinovaginal bulbs

Question 41

The precursor for all steroid hormones is ___

Answer 41

cholesterol

Question 42

Progesterone is both

Answer 42

an active steroid hormone and an important intermediary.

Question 43

What would happen if 21α-hydroxylase was missing

Answer 43

Progesterone wouldnt be able to convert into Aldosterone and Cortisol The extra progesterone instead would be converted to testosterone (/estrogens)

Question 44

What would happen if 11 β-hydroxylase was missing

Answer 44

Same as 21α - Abundance of testosterone, shortage of Cortisol and Aldosterone

Question 45

Congenital adrenal hyperplasia is usually due to deficiency in which enzyme

Answer 45

21α-hydroxylase Deficiency of Cortisol (and sometimes Aldosterone) occurs, which causes fetal pituitary to make more ACTH. With enough ACTH, finally cortisol is made… but MUCH MORE androgen is made as well. The adrenals enlarge because of all the cortisol precursor they make

Question 46

Urine test for CAH

Answer 46

Serum 17-OHP, will be elevated

Question 47

A less-active form of estrogen, created in low levels in fat cells when steroids are stored there

Answer 47

Estrone

Question 48

The major form of estrogen made by the ovaries | The most hormonally-active form of estrogen

Answer 48

Estradiol

Question 49

Much less active form Created in small amounts in the liver Created in higher amounts in the placenta Can be used as a marker for NTD’s

Answer 49

Estriol

Question 50

Peripheral Hormone Conversions | occur in the presence of ______

Answer 50

Aromatase Androstenedione >> Estrone Testosterone >> Estradiol