ansc 224: exam 3

describe the development of the posterior & anterior pituitary

1. posterior pituitary

• infundibulum: floor of brain

1. anterior pituitary

• rathke's pouch: derives from roof of mouth

describe why XY chromosomes could lead to ovary formation

• deletion or mutation of SRY

  • proving that SRY is necessary for testis formation

describe why XX chromosomes could lead to testis formation

• insertion of SRY via translocation of a piece of Y

  • proved SRY is sufficient

describe the function & purpose of Sox 9

• transcription factor (TF) increased by SRY proteins

• alters transcription of a variety of genes & turns off SRY gene

  • in lead, turns on FGF9 & AMH (anti-mullerian hormone)

state location of production of SRY

by testis at time of differentiation by pre-sertoli cells (non-germ cells)

describe female tract develppment

fused paramesonephric ducts to make future cervix & uterine body

describe hormones from fetal testis

1. anti-mullerian hormone (AMH): regression of mullerian ducts

1. testosterone: development of mesonephric duct

2. 5a-dihydrotestosterone (5a-DHT): via 5a-reductase, development of external genitalia

3. estradiol: via aromatase, sexual differentiation of the brain

define true hermaphrodistism

organs of both sexes

define pseudohermaphroditism

phenotype different than gonads

1. male

a. androgen insensitivity syndrome (AIS): mutation in androgen receptor; no response to testosterone or DHT produced

b. guevodoces: deletion or mutation in 5a-reductase

1. female

a. congenital adrenal hyperplasia: low glucocorticoids, excess androgen; increase of androgens in response to low glucocorticoids

describe sex differentiation of PGCs

• occurs after morphological sex differentiation of gonads

• regulated by gonadal environment (testis or ovary)

• independent of sex chromosomes (XX, XY) of PGC