Reproduction 1 Flashcards
(29 cards)
Differentiate between sex and gender.
- sex = chromosomes
- gender = societal, secondary sex, genitalia
What is the hierarchy of gender determination?
chromosomes => gonads => genitalia => gender identity
- gonad development is completely genetic
- genitalia and identity is due to hormones, society, genitalia
How is gonadal sex determined?
Chromosomes
- SRY gene (either on X or Y) ====> testes
- targets SOX9
Y defines the guy
Describe embryonic gonadal development.
- gonadal ridge of epithelial cells
- primordial germ cells migrate to ridge
- primordial gonad is indifferent
- specific gene expression determines testes vs ovary
==> SRY + SOX9 = testis
==> no SRY => overexpression of Rspo1 + Wnt => ovary
What does the gonadal ridge form?
- cortex becomes female internal genitalia
- medulla becomes male internal genitalia
Provide an overview of embryonic male development.
- indifferent gonad
- proliferation of sex cords by SRY and SOX9
- sex cords enter the medulla
- differentiation of medulla => testis
Provide an overview of embryonic female development.
- indifferent gonad
- proliferation of cortical sex cords in absence of SRY
- cortical cords develop
- epithelial cells form cluster around cortical cells => primordial follicle
What are the main cell types in a testis?
- gametes (sperm)
- sertolli cells - make AMH
- leydig cells - secrete testosterone and DHT
What are the main cell types in an ovary?
- gametes (ova)
- follicular cells
==> granulosa cells - make estrogen and progesterone
==> thecal cells - make androgens
What are the structures of the indifferent internal genitalia?
- mullerian duct
- wolffian duct
- mesonephros (transient kidney) - regresses
Describe differentiation of male internal genitalia.
- sertolli cells make AMH and inhibin B
=> AMH causes regression of mullerian duct - leydig cells make testosterone/DHT
=> causes proliferation of wolffian duct - testosterone causes differentiation of epididymis, vas deferens, seminal vesicles, ejaculatory duct
- DHT causes differentiation of prostate and scrotum
How do you make DHT?
require 5-alpha-reductase
converted from testosteron
Describe differentiation of female internal genitalia.
- no testes => no AMH, no testosterone => presence of mullerian duct, no wolffian
- mullerian differentiates into fallopian tubes, uterus, and distal 1/3 of vagina
How does having a testis affect the duct system?
- presence of testis = presence of wolffian
- no testis = no wolffian, yes mullerian
How does having an ovary affect the duct system?
- doesn’t matter
- you’ll get mullerian because there’s no testis
What happens in males, early castrate, with testosterone?
- no testis, but yes testosterone
- mullerian and wolffian
What happens in females, early castrate, with testosterone?
- no ovary, no testis, yes testosterone
- mullerian, and wolffian
Differentiate male and female for the follow structures:
- genital tubercle
- urogenital folds
- urogenital sinus
- labioscrotal folds
Males
- glans penis
- ventral penis
- prostate
- scrotum
Females
- clitoris
- labia minora
- lower vagina
- labia majora
Define propecia.
- hair loss tx
- inhibits 5-alpha-reductase
- lower androgen activity => stops hair loss
- careful in women: if exposed when pregnant, can’t develop prostate or scrotum in male fetus
Describe the process of spermatogenesis.
- mitosis begins with spermatogonia (diploid)
- mitosis ends with diploid primary spermatocyte (double DNA)
- meiosis I leads to secondary spermatocyte (haploid)
- meiosis II leads to spermatid (haploid)
- maturation leads to spermatozoa
What is unique about female oogenesis?
- arrested in meiosis I until puberty (diploid primary oocyte)
- arrested in meiosis II until fertilized (haploid)
- differentiation yields 1 oocyte and 1 polar body
Define OMI.
- oocyte maturation inhibitor
- secreted by follicular cells
- arrest in meiosis
What are possible chromosomal abnormalities that can lead to atypical gender?
- translocation (SRY gene on X; no SRY on Y)
- inversion
- deletion
- chimerism (exchange of genetic information b/w genetically distinct gametes)
- mosaicism (x inactivation)
- aneuploidy (wrong number chromosomes)
Define Turner’s Syndrome.
- XO
- no ovary because you need XX => gonadal streak tissue
- phenotypically female
- infertile
- sometimes webbed neck, short stature
- diagnosed at puberty due to lack of menses
