Chapter 6: Sexual Development Flashcards
(50 cards)
Genetic Sex?
- set at fertilization
Jost’s study with rabbits revealed what about genetic sex?
- female development is the default pathway
- removal of the ovaries = no change in development
- removal of testicles = development into females
Sex is usually determined by the presence of what gene located on the Y chromosome?
- SRY gene
SRY Gene:
- Any embryo that possesses at least one _ chromosome will develop into a male (with some exceptions)
- Y
Atypical Development: 1. Turner's Syndrome? L> issue with? L> physical appearance ? L> cognitive deficits? L> first indicator? L> treatment?
- single x chromosome or a truncated portion of an c chromosome
L> physically— shrunken ovaries, no gland or hormones, short stature, some other etc …
L> cogntiive deficits: visuospatial difficulties, memory and attention probs
L> webbed neck = first indicator
L> treatment= GH, androgens and estrogen
Atypical Development: 2. Klinefelter's Syndrome - location of issue? - physical symptoms? L> when do they become full blown? - endocrinological flaws?
- single Y chromosome, multi x…ex XXY
- gynecomastia (enlargement of breast tissue in males)
- feminine body contours, sparse facial hair and body hair
- full syndrome at puberty
- low testosterone levels
- sperm count is too low for normal fertility
- no sex drive
The SYR gene and others direct the development of the ___.
gonads
SYR gene and others directing gonads:
1. Sexual differentiation in both/one sex involves both ___ and ___.
- both
- gene activation and suppression
SYR gene and others directing gonads:
2. At five weeks post-conception, male embryos begin to what?
- express the SRY gene
SYR gene and others directing gonads:
3. Explain the product of the SYR gene
- transcription factor that turns on other genes such as SOX9 which directs and maintains testicular development
SYR gene and others directing gonads:
4. FOXL2???
- located on the X chromosome , it suppresses SOX9 and the development of testicles
The male and female reproductive tracts develop from similar or different precursors?
- different
The male reproductive tract develops from ___;whereas, the female reproductive tract develops from the ____.
- Wolffian Ducts
- Mullerian
Are both the wolffian and mullerian ducts present in both sexes?
- YES
In males the mullerian duct is suppressed by what?
- anti-Mullerian hormone
Testosterone from the Leydig cells begins being produced at ___ weeks and peaks at - weeks, directing the development of the Wolffian ducts.
- 8 weeks
- 12-16 weeks
Male and female external genitalia develop from the same or different precursors?
- SAME
- homologous - having a common origin / precursors
List which structures of the external genitalia are homologous with each other across sexes.
- scrotum - labia majora
- shaft of penis - labia minora
- glans of penis - glans of clitoris
Do female or male genitalia develop by default?
- female
Does removal of the ovaries change the process of development when it comes to being female?
- no
In male fetuses, testosterone is required/or not required for regular development of the genitalia?
- it is required
- developing genitalia express androgen receptors and 5alpha-reductase ( which converts T to DHT)
Atypical Development:
- Congenital Adrenal Hyperplasia ? (CAH)
- reduced production of?
- excessive growth of ?
- excessive production of?
- What happens to XX individuals?
- Brain Masculinization ?
- treatment?
- reduced production of steroids form the adrenal cortex
- excessive growth of adrenal cortex (compensation mech of body)
- excessive adrogen production
- XX individuals are partially masculinized during fetal and postnatal development (enlarged clitoris, partially fused labia majora)
- brain masculinization:
L> behaviour is more male like in terms of preferences for toys aggressive play etc… higher incidence of sexual attraction to women (37%) - surgical correction
- life long administration of corticosteroids.
When comparing Boys, girls and girls with CAH…how is time divided among boy toys and girl toys?
- boys and CAH girls are fairly close when playing with boy toys.(girls are lower)
- boys and CAH girls are similarly on the low end of playtime with girl toys vs girls.
- Neutral toys they all play about equal
Atypical Development:
2. 5 alpha-reductase deficiency syndrome?
- found in what kind of communities?
- genotype of sex?
L> they develop ovaries or testes?
- they do or do not produce AMH and T
- internal reproductive structures are masculine or feminine ?
- External genitalia develop or do not develop properly?
- typically found in genetically isolated communities
- XY males
- develop testes
- produce AMH(anti-mullerian hormone) and Testosterone
- Internal reproductive structures are masculine
- External genitalia do not develop properly
