2009 BGD-B Lecture Sexual Differentiation: Difference between revisions
Line 94: | Line 94: | ||
* External Genitalia | * External Genitalia | ||
* Gonadal Descent | * Gonadal Descent | ||
===Chromosomal=== | |||
* Turner’s Syndrome | |||
* Monosomy XO | |||
99% non-viable embryos | |||
Fail to sexually mature at puberty | |||
* Klinefelter’s Syndrome | |||
47, XXY | |||
Begin normal male, become infertile | |||
Tall, mental dullness, behaviour problems | |||
Males | |||
46, XX | |||
Develop as male, infertile adults | |||
Part of SRY gene located on one X | |||
Sex Reversal in Humans | |||
Hermaphroditism True (46,XX) | |||
Gonads both ovary and teste tissues | |||
Ovotestes or ovary and testes | |||
Male Pseudohermaphrodites (46,XY) | |||
Gonads of one sex, external genitalia of opposite | |||
Various causes | |||
Female Pseudohermaphrodites (46,XX) | |||
Gonads are ovaries, external genitalia ambiguous | |||
Hyperplastic adrenals secrete androgens | |||
Gonadal Dysfunction | |||
Gonads fail to develop properly | |||
Gonadal Dysgenesis | |||
Swyer’s syndrome (46,XX) | |||
Mixed Gonadal Dysgenesis (45,X/46,XY) | |||
Primary Hypogonadism | |||
Affected females 46,XX | |||
Primary Hypogonadism | |||
Defective anterior pituitary production of gonadotropin | |||
Lack of gonadotropin-releasing hormone | |||
===Tract Abnormalities=== | |||
Many different forms | |||
Uterine | |||
* Associated with other anomalies | |||
* Paramesonephric duct (0.1-0.5% of women) | |||
* several classifications | |||
* Unicornuate, bicornuate uterus | |||
Vagina | |||
* Agenesis, atresia | |||
* See also [http://embryology.med.unsw.edu.au/Notes/endocrine2.htm endocrine disruptors] | |||
Ductus Deferens | |||
* Uni- or bilateral absence | |||
* Failure of mesonephric duct to differentiate | |||
External Genitalia | |||
* Multi-factoral | |||
* Chromosomal, single gene, environmental | |||
* Developmental arrest gives ambiguous | |||
Hypospadias | |||
* Common male (1 in 300) | |||
* failure of urogenital folds to fuse | |||
* results in a proximally displaced urethral meatus | |||
===Gonadal Descent=== | |||
Cryptorchidism | |||
* One or both testes fail to descend into scrotum | |||
* 1:30 live male births | |||
* May be associated with other abnormalities | |||
Undescended Ovaries | |||
* reasonably rare, also be associated with other uterine malformations (unicornuate uterus) | |||
Virilization of a Genetic Female with Ovaries | |||
* Fetal androgens | |||
** congenital adrenal hyperplasia (CAH) | |||
** adrenal adenoma or hyperplasia | |||
* Maternal androgens | |||
** ovarian or adrenal tumors | |||
* Latrogenic | |||
** exogenous androgens or progestagens with androgenic activity | |||
Androgen Insensitivity Syndrome | |||
* XY karyotype and presence of testes | |||
* Externally - develop female secondary sex characteristics | |||
* Internally - women lack Müllerian duct derivatives, have undescended testes |
Revision as of 16:57, 27 May 2009
Introduction
This lecture is still available online with links to powerpoint slides as PDF for printing online lecture.
This current page is only in the early developmental stage and not complete.
BGD Genital 2009 Lecture Slides
The links below to PDF versions of lecture slides.
- 1 slide/page (52 pages 1.25 Mb)
- 4 slides/page (13 pages, 803 Kb)
- 6 slides/page (18 pages, 776 Kb)
- Lecture Handout (5 pages 172 Kb)
Lecture Overview
- Gonad
- Internal Genitalia
- Reproductive Tract
- External Genitalia
- Development
- Function
- Abnormalities
Background Reading
UNSW Embryology
NIH Bookshelf
- Developmental Biology (Gilbert) Chapter 17
- Endocrinology (Nussey and Whitehead) The Gonad
Textbook References
- Human Embryology (3rd ed.) Larson Chapter 10 pp266-313
- The Developing Human (6th ed.) Moore & Persaud Chapter 13 p303-346
- Before We Are Born (5th ed.) Moore & Persaud Chapter 14 p289-326
- Essentials of Human Embryology, Larson Chapter 10 p173-205
- Human Embryology, Fitzgerald and Fitzgerald Chapter 21-22 p134-152
Genital System Development
3 stages
- Differentiation of gonad (sex determination)
- Differentiation of internal genital organs
- Differentiation of external genital organs
2nd and 3rd stages dependent on endocrine gonad
- Long Maturation Time-course
- Begins in embryo
- Continues through fetal
- Finishes in puberty
Sex Chromosomes
X Chromosome
- 1400+ genes
- 150 million base pairs
- 95% determined
Y Chromosome
- 200+ genes
- 50 million base pairs
- 50% determined
Sex Determination
- Humans (week 5-6)
- Germ cells migrate into gonadal ridge
- Gonads (male/female) identical at this stage (Indifferent)
Gonad development dependent on sex chromosome
- Y present testes
- No Y ovary
DNA with SRY Protein SRY protein binds DNA
Testes determining factor (TDF)
- Transcription factor
- Bends DNA 70–80 degrees
Genital Abnormalities
- Chromosomal
- Hermaphroditism
- Gonadal Dysfunction
- Tract Abnormalities
- External Genitalia
- Gonadal Descent
Chromosomal
- Turner’s Syndrome
- Monosomy XO
99% non-viable embryos Fail to sexually mature at puberty
- Klinefelter’s Syndrome
47, XXY Begin normal male, become infertile Tall, mental dullness, behaviour problems Males 46, XX Develop as male, infertile adults Part of SRY gene located on one X Sex Reversal in Humans
Hermaphroditism True (46,XX) Gonads both ovary and teste tissues Ovotestes or ovary and testes
Male Pseudohermaphrodites (46,XY) Gonads of one sex, external genitalia of opposite Various causes
Female Pseudohermaphrodites (46,XX) Gonads are ovaries, external genitalia ambiguous Hyperplastic adrenals secrete androgens Gonadal Dysfunction Gonads fail to develop properly Gonadal Dysgenesis
Swyer’s syndrome (46,XX)
Mixed Gonadal Dysgenesis (45,X/46,XY)
Primary Hypogonadism Affected females 46,XX Primary Hypogonadism Defective anterior pituitary production of gonadotropin Lack of gonadotropin-releasing hormone
Tract Abnormalities
Many different forms
Uterine
- Associated with other anomalies
- Paramesonephric duct (0.1-0.5% of women)
- several classifications
- Unicornuate, bicornuate uterus
Vagina
- Agenesis, atresia
- See also endocrine disruptors
Ductus Deferens
- Uni- or bilateral absence
- Failure of mesonephric duct to differentiate
External Genitalia
- Multi-factoral
- Chromosomal, single gene, environmental
- Developmental arrest gives ambiguous
Hypospadias
- Common male (1 in 300)
- failure of urogenital folds to fuse
- results in a proximally displaced urethral meatus
Gonadal Descent
Cryptorchidism
- One or both testes fail to descend into scrotum
- 1:30 live male births
- May be associated with other abnormalities
Undescended Ovaries
- reasonably rare, also be associated with other uterine malformations (unicornuate uterus)
Virilization of a Genetic Female with Ovaries
- Fetal androgens
- congenital adrenal hyperplasia (CAH)
- adrenal adenoma or hyperplasia
- Maternal androgens
- ovarian or adrenal tumors
- Latrogenic
- exogenous androgens or progestagens with androgenic activity
Androgen Insensitivity Syndrome
- XY karyotype and presence of testes
- Externally - develop female secondary sex characteristics
- Internally - women lack Müllerian duct derivatives, have undescended testes