Lecture 5 - Sex Differences 1 Flashcards Preview

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What are the types of sex differences

Genetic or chromosomal sex
Gonadal sex
Internal reproductive system
External reproductive system
Pubertal sex changes
Hormonal sex
Brain sex
Behavioural and cognitive sex
Sexual identity


What is genetic or chromosomal sex

23 chromosomal pairs in humans
1 pair sex chromosome
XX - female
XY - male
Genetic sex determined by speed
Divide into 4 sex cells - haploid


Outline sexual differentiation

Genetic sex determines sex of gonads release hormone associated sexual differentiation
Activations effects of sex hormones produced by gonads
Hormone effects depend previous organisational effects


What are the sexual differentiation effects before birth

Organisational effects sex hormones produced by feral gonads


What are the permanent alterations in sexual differentiation

Permanent alterations in body or CNS induced by hormone at critical period in development


What is the development of sex organs

Gonads (ovaries and testes) and internal sex organs
Start with undifferentiated gonads and internal and external sex organs undifferentiated
Pre modial gonads and sex organs develop into make or female sex type organs


Outline SRY determining the development of make sex organs

SRY region Y chromosome codes for testis determining factor - transcription factor
Bond DNA cells undifferentiated gonads
Causes them become testes
Primordial gonads develop into testes


Outline testes in development make sex organs

Testes produce hormones defeminising
Anti mullerian hormone
Masculinising androgen effects
Mullerian system withers away


Outline what occurs with masculinising effects of Androgens

Androgens masculinising wolffian system develops vas deferns seminal vesicles prostate
Primordial external de italics develop into penis and scrotum


What is the Anti Mullerian Hormone

Peptide secreted by feral testes
Defeminising effects
Inhibits development of Mulleria System
By acting on anti mullerian hormone receptors in cells that system


What is the Mulleria System

Precursor of female internal sex organs


What 2 androgens determine male sex organs




How does the Androgen Testosterone act as primary cause masculinisation during early development

Testosterone acts androgen receptors cells Wolffian System
Stimulates its development into male internal sex organs


How does testosterone act in the nucleus and lead to sexual differentiation before and after birth

Acts in nucleus as structure passes through membrane
Transcription factors trigger certain gene production


How does the Androgen Dihydrotestosterone act as primary cause masculinisation during early development

Acts on androgen receptors in primordial external genitals = higher affinity than testosterone
Critical stimulate their development into male genitals


Where and how is Dihydrotestosterone produced

Produced from testosterone by 5alpha reductase


Outline Testes determine factor study by Werner et al 1995

230 amino acid long protein coded for by SRY region of Y chromosome
Transcription factor binding DNA
Inducing conformational changes enable transcription
Mutations prevent development testes = hence internal and external male sex organs in XY organs
- be genetically male not develop testes due mutation SRY


How do genetics contrast to religion

Religion female secondary to male
Biologically default we are females first
By hormones become males


Outline the default of primordial sex organs developing in to female sex organs

Absence testis determining factor primordial gonads develop into ovaries
Absence androgens produced testes internal and external sex organs develop into female organs
Without any other normal influences


Outline how Primordial gonads develop into Ovaries

Mullerian system develops in to fimbriae Fallopian tubes uterus inner vagina

No hormones wolffian System without androgens withers away

Primordial external genitalia develop into clitoris labia outer vagina


What is Swain 2017 discovery on Wolffian System

Wolffian System regression requires COUP-TF11
A nuclear reception so not passive process


What are the different types of abnormal development of sex organs

XY sex reversal

Androgen insensitivity syndrome

Turners syndrome

Persistent Mullerian Duct Syndrome


Outline abnormal development of sex organs: XY sex reversal

Point mutations in SRY region Y chromosome result female sex organs in XY individuals


Outline abnormal development of sex organs: Androgen Insensitivity Syndrome

Conditioned caused by congenital lack functioning androgen receptors
In person XY sex chromosomes
Causes development female with testes but no internal sex organs


Outline abnormal development of sex organs: Turners Syndrome

Presence only 1 sex chromosome X
Result in lack ovaries otherwise normal female sex organs and genitalia


Outline abnormal development of sex organs: Persistent Mullerian Duct Syndrome

Congenital lack anti mullerian hormone causes development both male and female internal sex organs in XY


Outline different primary sex characteristics and secondary sex characteristics

Primary sex characteristics - gonads internal and external sex organs. Present at birth

Secondary sex characteristics - enlarged breasts widened hips facial hair deep voice. Sexual maturity not developed until puberty


Define secondary sex characteristics

Control reproductive functions and sexual behaviour

Axillary and pubic hair in females stimulated by testosterone produced by Cortex of adrenal glands


How is puberty triggered

Hypothalamus secretion of gonadotropin releasing hormone
Stimulates pituitary gland release gonad stimulating hormones
Same males and females
Either act in male gonads - testes or female gonads - ovaries
Producing testosterone or oestrogen


Why do peptides stimulate gonads

Produce steroid sex hormones sit on outside of cells