Exam 1: Embryology of the Reproductive Tract Flashcards
Where does fertilization occur?
Ampulla of the uterine tube
________ and ________ do not have oviducts
Dogs and cats
What is a gamete?
Oocyte or sperm- Haploid
What is a zygote?
Fused gametes- Diploid
What are the layers of the blastocyst and what will they
eventually become?
Inner Cell Mass (Embryoblast) - Embryo
Trophoblast- Placenta
Blastocoele- Fluid filled space
Which organized cell layer becomes the
skin, eyes, and teeth?
ECTOderm
Which organized cell layer becomes the
muscles, skeleton, and most of the repro tract?
MESOderm
Which organized cell layer becomes the
gut, respiratory system, and abdominal organs (pancreas, liver)?
ENDOderm
The urogenital sinus is an outpouching of
hindgut _______
ENDOderm
Primordial germ cells get surrounded by cells of the
primitive gonad and become _______ _______
Sex Cords
Germ cells surrounded by sex cords become
_______ in females
and
_______ in males
Granulosa cells (oocyte/follicle) - Female
SERTOLI cells - Male
Genetic/Chromosomal sex
is determined at ___________
fertilization
In mammals, the heterogametic is the male
but in __________, the heterogametic is the female
BIRDS
What are the testis determining genes
responsible for gonadal sex differentiation?
SRY, SOX9
What are the ovary determining genes
responsible for gonadal sex differentiation?
RSPO1, WNT
Which hormone is responsible for
phenotypic sex differentiation and subsequently
testosterone and dihydrotestosterone production?
AMH (Anti-Mullerian Hormone)
- Causes regression of the mullerian/peramesonephric duct*
- leading to regression of the female tract*
SRY testis determining factor is synthesized in
the ________ of the male
sex cord
_______ sex cords differentiate into Sertoli Cells
while
________ sex cords degenerate
Medullary sex cords - Sertoli Cells
Cortical sex cords - degenerate
________ cells, in addition to the early male gonad
produce Anti-Mullerian Hormone
Pre-Sertoli cells
In absence of SRY,
________ sex cords develop into follicles
while
________ sex cords degenerate
Cortical sex cords - follicles
Medullary sex cords - degenerate
The paramesonephric duct develops at about
______ weeks in both sexes
6 weeks
The urogenital sinus forms as an outpouching of the hindgut
and is continuous with the ________, and forms the bladder
and pelvic urethra which is contacted by the ureters.
Urachus
In the indifferent stage of external genetalia formation,
the pair of swellings lateral to the cloaca are called
________ ________
cloacal folds
Cranial portion of the cloacal folds fuse to form the
_________ __________
urogenital tubercle
The cloacal folds fuse to form the
urogenital tubercle which goes on to become the
_______ in males
or the
_______ in females
penis
clitoris
How many days into pregnancy are you able to sex a fetus?
60 - 80 days (7th week)
The ligamentous cord from gonad to skin
that makes its way through the abdominal muscles and
ends in the region of the labioscrotal swellings
in the 7th week of gestation
Gubernaculum
When the gubernaculum reaches the labioscrotal swellings
in the 7th week, this turns into the
_______ in males
and the
________ in females
Processus vaginalis (males- the cavity inside the scrotum)
and the
Ovarian ligament and round ligament of the uterus (females)
The _______ center of the hypothalamus makes
pulses of GnRH which governs transition to puberty in females
TONIC
The _______ center of the hypothalamus in females
has high frequency pulses of GnRH, which superstimulates the
anterior pituitary to release ______, the hormone
important for initiating ovulation
SURGE center
LH
Testosterone cross the BBB and is converted to ________
which defeminizes the hypothalamus
and
eliminates the surge center
Estradiol
Fetal ovaries produce estradiol, but it does not cross the BBB
because it is bound to __________
alpha-fetoprotein
In temperature dependent sex determination,
phenotypic sex is irreversibly determined mid-incubation
during the __________ period
Thermosensitive
Disagreement between chromosomal and gonadal sex
resulting in varying degrees of male-ness
Sex reversal
In XX-sex reversal in goats, this condition is
linked to hornlessness due to a large genetic deletion
Polled intersex (PIS)
This breed of dog has higher incidences of XX-sex reversal
American Cocker Spaniel
In Freemartin cows, fusion of allantoic blood vessels results in male and female co-twins that are both ______,
meaning they are composed by cells from 2 different zygotes.
chimeras
The daughters of fertile bulls with testicular hypoplasia
tend to have this developmental abnormality
Hypoplastic ovaries
T/F:
Germinal inclusion cysts found in the ovulation fossa
of mares, can resemble granulosa cell tumors and cause
infertility
TRUE
These 2 congenital lesions occur in white shorthorns cows
with White Heifer Disease.
Persistent hymen
and
Segmental aplasia
(usually means they have only one uterine horn)
Failure of fusion of paramesonephric ducts
can result in a double cervix, which is common
in _____ but rare in other species
cows
Failure of fusion of paramesonephric ducts can result in
vaginal cords/septum which are important in this species
Dogs
This condition common in filliies,
occurs when the fetal vaginal membrane fails to perforate,
which can result in an unbred female horse (filly) displaying
signs of foaling.
Imporforate hymen
This fundamentally genetic condition can result
in a 10x greater risk of primary testicular tumors,
especially Sertoli Cell Tumors,
as well as an increased risk
of testicular torsion
Cryptorchidism
Which breed of horse is predisposed to
Cryptorchidism?
Quarter Horses
What is the most common location of a retained testicle
in Cryptorchid horses and which testicle is more common?
Abdomen, Left testicle
In equines, this type of tumor along with Sertoli Cell tumors
can accompany cryptorchidism
Teratoma
This breed of bovine is predisposed to testicular hypoplasia
Swedish Red
A congenital lesion where the urethra opens on the
ventral surface of the penis
Hypospadias
In this congenital disorder,
seen in humans but rare in domestic animals,
the urethra opens on the dorsal surface of the penis
Epispadias
