Normal and Abnormal Sexual Development

Question 1

_________ gene regulates the inactivation of one X chromosome in female

Answer 1

XIST

Question 2

what are the four levels of sexual differentiation?

Answer 2

chromosomal
gonadal
internal sexual organs
external genitalia

Question 3

what does the “silenced” X chromosome become?

Answer 3

Barr body

Question 4

what is one gene involved in gonadal differentiation located on autosomal chromosomes?

Answer 4

steroidogenic factor-1 (SF-1)

Question 5

what autosomal genes lead to development of sertoli cells?

Answer 5

SOX-9
repressor element

Question 6

what does the gene Wnt-4 do?

Answer 6

suppresses leydig cell development
paramesonephric duct development

Question 7

what activates the steroidogenic enzymes necessary to synthesize testosterone?

Answer 7

steroidogenic factor-1 (SF-1)

Question 8

what leads to development of male external genitalia?

Answer 8

5alpha-dihydrotestosterone (5alpha-DHT)

Question 9

_________________ is converted to 5alpha-dihydrotestosterone

Answer 9

testosterone

Question 10

what converts testosterone into 5alpha-dihydrotestosterone?

Answer 10

5alpha-reductase

Question 11

what is 5alpha-dihydrotestosterone needed for development of?

Answer 11

prostate
bulbourethral glands
penis
scrotum

Question 12

does the primordial contain 5alpha-reductase in both the male and female embryo?

Answer 12

yes

Question 13

what is testosterone converted into in the brain?

Answer 13

estradiol by aromatase

Question 14

what is intersex?

Answer 14

an animal with characteristics of both sexes: chromosomal, hormonal, and/or internal organ/external genitalia level

Question 15

what are the three main categories of disorder of sexual development?

Answer 15

sex chromosome disorder of sexual development
XX disorder of sexual development
XY disorder of sexual development

Question 16

what is a chimera?

Answer 16

animal that is a mix of two genetically distinct cells that originated from different embryos

Question 17

what is a mosaic?

Answer 17

animal that contains two or more genetically different cells

Question 18

what is a true hermaphrodite?

Answer 18

gonadal tissue of both sexes present

Question 19

what are some conditions associated with chromosomal anomalies?

Answer 19

XO gonadal dysgenesis of horses
seminiferous tubular dysgenesis
freemartin- chimerism in cattle

Question 20

what are some features of XO gonadal dysgenesis of horses?

Answer 20

similar to turner’s syndrome in humans
small height and weight
sterile, not estrous cycle
streak gonads

Question 21

what are some signs of seminiferous tubular dysgenesis (similar to kleinfelter’s in humans) (XXY)?

Answer 21

atrophic testes
lack of secondary male characteristics
infertility associated with the absence of striking reduction in sperm
lower than normal serum testosterone

Question 22

what is a male calico cat almost always?

Answer 22

XXY

Question 23

what type of chimeras are freemartins?

Answer 23

hematopoietic

Question 24

what is the freemartin effect caused by?

Answer 24

testicular tissue forming in the female ovary: AMH/MIS and androgens

Question 25

what are some traits of freemartins?

Answer 25

shortened/incomplete vagina formation of vesicular glands hypoplastic gonads/streak gonads hypoplastic vulva enlarged clitoris

Question 26

what are some types of gonadal dysgenesis?

Answer 26

gonadal hypoplasia XY gonadal dysgenesis gonadal dysgenesis related to chromosomal anomalies- sex chromosome DSD

Question 27

what type of gene is swedish highland breed ovarian hypoplasia?

Answer 27

autosomal recessive gene

Question 28

what is the phenotypic appearance in XY gonadal dysgenesis?

Answer 28

appear to be females

Question 29

what are the ovaries like in XY gonadal dysgenesis?

Answer 29

small with no, or reduced numbers of ova often streak ovaries

Question 30

what are some ways that gonadal sex differs from internal reproductive organ and/or external genitalia sexual development?

Answer 30

XX sex reversal androgen insensitivity persistent mullerian duct syndrome of miniature schnauzers drug induced intersexuality

Question 31

what happens in XX sex reversal with the genes?

Answer 31

XX, but SRY/TDF (or other male associated fertility gene) is located on paternal X or on autosome

Question 32

what is the Y effect gene (recessive) in the polled goat intersex associated with?

Answer 32

polled gene (dominant)

Question 33

what is the problem in females with polled goat intersex?

Answer 33

variably masculinized

Question 34

are individuals with androgen insensitivity XY or XX?

Answer 34

XY

Question 35

describe the phenotype of individuals with androgen insensitivity (XY DSD)

Answer 35

testes in abdomen male internal reproductive organs external phenotype is female

Question 36

what are testosterone levels like in androgen insensivity?

Answer 36

high

Question 37

what is the etiology of androgen insensitivity?

Answer 37

deficiency of androgen receptors

Question 38

what are individuals with persistent mullerian duct syndrome of miniature schnauzers phenotypically?

Answer 38

male

Question 39

what sex organs do individuals with persistent mullerian duct syndrome of miniature schnauzers have?

Answer 39

cryptorchid testes uterus

Question 40

what might XY pseudohermaphrodite syndrome (persistent mullerian duct syndrome) of miniature schnauzers be due to?

Answer 40

lack of AMH/MIF

Question 41

when can problems develop with drug induced intersexuality (XX DSD or XY DSD)?

Answer 41

pregnant animals administered hormones (testosterone, estrogen) or substances that act like these hormones

Question 42

when diagnosing DSD, what should you determine?

Answer 42

if the problem is at the level of the sex chromosomes, gonads, internal reproductive organs, or external genitalia

Question 43

what does steroidogenic factor-1 control?

Answer 43

gonadal differentiation androgen production anti-mullerian hormone/mullerian inhibiting substance production

Question 44

what does Wnt-4 support the development of?

Answer 44

paramesonephric duct

Question 45

what does sexual behavior depend on?

Answer 45

hormonally driven development of appropriate areas of the brain during gestation

Question 46

what do XO gonadal dysgenesis of horses, seminiferous tubular dysgenesis, and freemartins all have?

Answer 46

gonadal dysgenesis

Question 47

what is the karyotype of freemartins?

Answer 47

60XX 60XY

Question 48

what is XY gonadal dysgenesis phenotypically similar to in people?

Answer 48

complete androgen insensitivity syndrome: have testes and produce testosterone

Question 49

do animals with androgen insensitivity have uteruses?

Answer 49

no

Question 50

how can you diagnose androgen insensitivity?

Answer 50

testosterone levels karyotyping

Question 51

what happens in congenital adrenal hyperplasia that viralizes the fetus?

Answer 51

gland of fetus produces excess androgen