Chapter 14- Reporting Flashcards
it was influenced by heat during intercourse and the environment, to the modern understanding that it is primarily determined by the X and Y chromosomes.
Sex determination
carries a gene that encodes
a testis-determining factor, crucial for male sex determination
Y chromosome
An individual with any number of
X chromosomes and a Y chromosome will be
_______, while an individual with only X
chromosomes will be _______, but a second X is
needed for a complete ovary
male, female
involves the development of non-gonadal sexual characteristics, which are typically influenced by hormones and paracrine factors from the gonads.
secondary sex determination
The sex of the offspring is
determined at fertilization by whether the egg
receives a second X (female) or a Y (male)
chromosome.
Primary sex determination
cells that form testis cords and also secrete a factor that blocks female duct development and supports sperm production
sertoli cells
cells that produce
testosterone
Leydig cells
It accumulate near the
outer surface of the
gonad and become ova
germ cells
remains intact
and differentiates into the
oviducts, uterus, cervix,
and upper vagina
Mullerian duct
a protein crucial for testis determination
Sox9
the sex determining gene on the Y chromosome
SRY gene
Two pathways of pathway for organogenesis
Male pathway and female pathway
act to block the ovary forming pathway, probably by blocking the function of
|3-catenin.
Sox9 and Fgf9
is also critical in ovary formation,
since in human case studies several XX
individuals with RSPOl gene mutations became males.
R- spondin
One possible target for β-catenin is the gene
encoding _________
TAFII105
is another gene that is strongly
upregulated in ovaries
FoxL2
- it causes proliferation of the Sertoli cell
precursors and stimulates their differentiation - activates the migration of endothelial cells from the adjacent mesonephros into the XY gonad
Fgf9
- the necessary to make the bipotential gonad.
- a critical link between SRY and the male developmental pathway
steroidogenic factor1 (Sf1)
is often called an “intersex”
but prefer to these conditions “disorders of sex development”
Hermaphrodites
- is sex-determining genes that located on
the X chromosomes. - is overproduced and the gonads develop into ovaries despite the presence of the Y chromosomes
DAX1
are involved in male sex determination
throughout the animal kingdom
Dmrt (double sex and mab-3-related transcription factor)
is the formation of either an
ovary or a testis from the bipotential gonad
Primary sex determination
They cannot respond to testosterone but can
respond to estrogen, so they
develop female secondary sex
characteristics
Androgen insensitivity syndrome
where male and female
traits are present in the same individual, are a
significant phenotype
intersex conditions
where the fetus is male but gonadally female, is often caused by overproduction of androgens in the ovary or adrenal gland, often due to congenital adrenal hyperplasia, which lacks an enzyme for testosterone metabolism.
female pseudohermaphroditism
is a primary masculinizing factor,
but may not be the active masculinizing
hormone in certain tissuesT
testosterone
is a growth and differentiation factor from the TGF-p family secreted from fetal Sertoli cells, causing Mullerian duct degeneration
Anti-Mullerian factor (AMF)
is crucial for fertility in both males and
females, influencing the development of the
Mullerian and Wolffian ducts
Estrogen
are regions of the brain that regulate
involvement during the fetal or
neonatal stages of sexual development
estrogen and estradiol
play a significant role in sexual
behaviors in rodents.
pheromones
an enzyme induced by estrogen, which increases the production of
PGE2.
prostaglandin E2
X chromosome contains genes encoding
transcription factors that activate the critical
gene in Drosophila sex determination, the
autosomal locus
Sex-lethal (Sxl)
gene is a gene in fruit flies that
helps determine their sex. It is responsible for
controlling whether a fruit fly develops as a male or a female.
Sex-lethal (Sxl)
active only in cells with two X
chromosomes (XX)
early promoter
active in both XX and XY cells
later promoter
three major targets of sex-lethal
- The pre-mRNA of Sxl itself
- The msl2 gene that controls dosage
compensation - The pre-mRNA of transformer (tra)
is active in both
males and females, but its primary transcript is processed in a sex specific manner.
doublesex (dsx) gene
a gene expressed in certain sets of neurons
involved with male sexual behaviors
fruitless
➢ Below 28°C, all the turtles
hatching from the eggs will be male.
➢ Above 31°C, every egg gives rise
to a female
red-eared slider turtle
➢ Female at either cool (22°C or
lower) or hot (28°C or above)
temperatures
➢ Male between 22°C and 28°C
macrolemys
➢ Temperatures above 30°C produces all females
➢ Temperatures below 25°C produce all-male
broods
➢ The threshold temperature (at which the sex ratio is even) is 28.5°C
European pond turtle
is influenced by
temperature, with low levels favoring male
development and higher levels favoring female development
aromatase activity
a class of widespread pollutants introduced into the environment by humans, can act as
estrogens
polychlorinated biphenyl compounds
