Genital Development Flashcards by Cordell Young

Q

Origin of …. Nervous system

A

ectoderm

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Q

Origin of ….muscle

A

mesoderm

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Q

Origin of ….digestive system

A

endoderm

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Q

Origin of ….urinary and skeletal

A

mesoderm

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Q

Origin of ….reproductive tract (vagina, vestibule, penis, clitoris)

A

ectoderm

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Q

Origin of ….skin, hair, nails, sweat glands

A

ectoderm

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Q

Origin of ….reproductive system (gonads, uterus, cervix, par of vagina, epididymus, ductus deferens, accessory sex glands)

A

mesoderm

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Q

First step after fertilization (2)

A

migration of primordial germ cells from yolk sac (first 15% of gestation)

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Q

second step after fertilization (2)

A

sex cords develop in gonad,

paramesonephric ducts develop

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Q

third step after fertilization (2)

A

sex is evident from structures (not just histologically anymore)

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Q

Sex determination (2)

A

initially at fertilization

subsequent genetic control of differentiation

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Q

What forms the germ line?

A

mesoderm and endoderm from epiblast cells (good for stem cell stuff)

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Q

What is the big journey?

A

primordial germ cells go from embryonic disk to yolk sac and part of the allantois
Chemotaxis is involved
Birds use passive methods through blood

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Q

What makes the ridges again?

A

intermediate mesoderm

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Q

Teratomata

A

bugs? that form teeth (tumors) on body walls or anything

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Q

on the ridge from thoracic to lumbar, ____ is medial and _____ is lateral

A

gonadal, urinary (main ridge)

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Q

Gonadal ridge cells come from… (3)

A

local mesenchyme
coelomic epithelium
mesonephric tubule cells

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Q

PGCs stimulate…

A

cells around to proliferate causing ridge elongation

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Q

Degenerating mesonephric tubules turn into…

A

compact strands of primitive sex cords which incorporate PGCs

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Q

WT-1 (2)

A

forms gonads

Wilmes Tumor -1

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Q

Lim-1

A

also required for gonad formation (absence leads to no gonads)

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Q

Steriodogenesis Factor -1

A

induces differentiation of Sertoli and Leydig cells

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Q

Sexually indifferent stage

A

Embryo is not committed to particular sex development.

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Q

Paramesonephric ducts = (2)

A

Mullerian ducts

develop when mesonephros is developing

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Two things in the first 10-15% of gest (2)

development of metanephros migration of PGCs to gonadal ridge Compare these two

Mesonephric duct becomes...

epididymus

SRY

on Y chromosome that determines

SRY gene (3)

On the Y chromosome (on sex determining region Encodes SRY protein which is made by primitive sex cords in the primitive gonad Stimulates male reproductive system

Genetic Sex Differentiation (2)

Differentiation where the SRY genes are enconded, the male reproductive system is stimulated

What do AMH and testosterone…

Degenerate the paramesonephric duct

Desert Hedge-hog (2)

At about 27% | Differentiates fetal Leydig cells which produce testosterone and DHT

Testosterone develops

Male duct system (around 33%)

DHT develops

Penis, scrotum, and accessory sex glands (around 33%)

SRY protein leads to…

Testes developing

Once the testes develop, …

Sertoli cells secrete AMH (Anti-Mullerian Hormone) and DHT

Presence of sertoli cells and what it secretes, ….

Expresses DHH gene and causes AMH and testosterone to do their work

Developmental sequence of Testes (5)

Sex cords align with rete tubules 5-15 mesonephic tubules will penetrate toward the rete tubules rete and mesonephric tubules interconnect (continuity now) Sex cords become epithelial (epithelial cords) paramesonephric duct degenerates (why?)

Tunica albuginea

outer layer of CT with coelomic epithelia

Mesonephric tubules become...

future efferent ducts

epithelial cords (sex cords) become...

seminiferous tubules

Two other names for mesenchyme in testes and function (3)

Interstitial cells Leydig cells primary testosterone

Function of sertoli cells (3)

Blood-testes barrier Increase testosterone around cells Differentiates cells (with help from Androgen Binding protein)

Function of androgen binding protein (2)

Binds to testosterone, DHT, and one more Makes these more lipophilic and artificially lowers concentrations so more testosterone and such moves in (acts as a sink)

Seminiferous cords come from

primitive sex cords and become solid tubules containing germ cells

Sertoli cells come from...

mesonephric derived cells

Development of seminiferous tubules, ..

15-20 mesonephric derived cells surround about 4 pre-spermatogonia

Function of Interstitial (mesenchymal, leydig) cells (3)

form CT septa to divide testes into lobules Less developed in ruminants Horses septa have smooth muscle

Semifierous cords become...

seminiferous tubules with a lumen

from the mesonephric duct inward... (6)

Mesonephric duct (also ductus deferens)---> the epididymis part of the mesonephric duct ---> efferent ducts ---> rete testes ---> seminiferous tubules. All surrounded by Tunica Albuginea

mesonephric duct becomes ... (2)

ductus deferens and epididymis

Excurrent Extragonal Duct System

efferent ducts, epididymis, and ductus deferens which carry sperm to urethra

Tubule canalization in horses...

2 years

Tubule canalization in humans

12-14 years

Tubule canalization in dogs

9-10 months

Tubule canalization in sheep

5 months

Tubule canalization in cows

6-8 months

Which accessory sex glands does a dog have

only the prostrate

accessory sex glands of a bull

bulbourethral glands, seminal vesicles, and ampullae ductus deferentis, prostate

accessory sex glands of a ram

bulbourethral glands, seminal vesicles, and ampullae ductus deferentis, prostate

accessory sex glands of a boar

bulbourethral glands, seminal vesicles, and ampullae ductus deferentis, prostate

accessory sex glands of stallion

bulbourethral glands, seminal vesicles, and ampullae ductus deferentis, prostate

accessory sex glands of lab animals

bulbourethral glands, seminal vesicles, and ampullae ductus deferentis, prostate

accessory sex glands of a cat

bulbourethral glands, (NOT seminal vesicles), and ampullae ductus deferentis, and prostate

Where do seminal vesicles and ductus deferens come from...

epithelial EVaginations from mesonephric duct

Prostrate and bulbourethral glands come from...

epithelial Evaginations from urogenital sinus

Accessory glands depend on..

androgens

Accessory glands happen at about what time..(2)

30% of gestation | same a duct system differentiation

gubernaculum (2)

ligamentous structure that grows and regresses quickly to allow the testes to move from retroperitoneal position to scrotum

No descent in....(4)

armadillos elephants aquatics Birds

Layers of peritoneum the testes have to go through (2)

visceral vaginal tunic | parietal vaginal tunic

Stages of testes descent (2)

transabdominal phase | inguinal-scrotal phase

Transabdominal phase (3)

testes (retroperit) attached to gubernaculum caudally Gubernaculum and peritoneal cells join gubernaculum grows towards and into the scrotal region

inguinal-scrotal phase (2 - big guys)

Gubernaculum penetrates inguinal ring and testes move into intestinal canal because of rapid gubernaculum growth (depends on androgens) gubernaculum shrinks moving testes into inguinal opening and further until peritoneum surrounds

Vaginal cavity

potential space between the visceral and parietal tunics in the scrotum

Testes for ruminants descend

mid-gestation

testes for boars and humans descend

last quarter

horses testes descend..

just before or after birth

Inguinal hernias

common in swine | ligate visceral and parietal tunics

When there is no SRY... (5)

``` Female genes inhibit male genes Ovaries develop No AMH The whole system develops 20-33% times in gestation ```

Dax-1

suppresses formation of testes

WNT 4 (2)

essential for formation of female repro tract | also, important to make full nephron

Streak gonads

a result of PGCs not making it to the ridge (medial ridge remember)

paramesonephric ducts become (2, 5 parts)

Infundibulum, oviducts, uterus, cervix, and part of vagina | at 27% of gestation

tip of the paramesonephric duct becomes

infundibulum (enlarges to become this)

Ovary Developmental sequence (4)

cells from sex cords break away(maybe), surround PGCs, and differentiate into primitive follicular cells Mesonephric duct regresses at the same time as the rete tubules. Primitive follicular cells surround PGCs stay in cortex Sex cords disappear and in it's place, the cortex and non-germinal medulla

PGCs in the ovary are called

oogonia

coelomic epithelium of the ridge become...

cortex of ovary

Follicles arrangement (3)

usually in the cortex of the ovary Dogs and cats are clustered Ruminants and swine are randomly distributed

Equine Ovary differences (3)

Follicles are in medulla ovaries are in close contact with epithelium and ovulation happens right there They have the ovarian fossa

Ovulation fossa is...

where more central oocytes can be released from | ovary becomes concave, keeping the coelom

Meso-salpinx

part of the broad ligament that goes from the ovary to the uterine tube

Oviduct is synonymous with

salpinx

Final position of ovaries after descending posteriorly... (2)

suspensory ligament of ovary | proper ligament of the ovary

Suspensory ligament used to..

suspend the mesonephros

proper ligament is a portion of the...

gubernaculum

Development of paramesonephric ducts (3)

open to abdomen cranially interacts with the urogenital sinus caudally the two fuse together near the attachment at the urogenital sinus

Caudal urogenital sinus becomes.. (female)

vestibule

Cranial urogenital sinus becomes... (female)

bladder

Fused paramesonephric ducts become .... (female)

cervix and uterine body

Mares and cows have _____ uteri

bicornuate

marsupials and rabbits have ______ uteri

duplex

bitch, queen, and sow have _______ uteri

bicornuate but really developed

Primate have _____ uteri

simplex

Gland development in the uterus makes...

histotrophe

gland development in pigs and sheep is

fast and right after birth

gland development in horses is

slow (all the way to puberty)

Steps in the development of female reproductive tract ducts (3 steps - not good for a notecard but whatever)

A small bud evaginates from urogenital sinus and fuses with paramesonephric duct (caudal part to caudal part) A more defined cervix forms by fusing with the paramesonephric duct The urogenital sinus then elongates

Vestibule originates from..

urogenital sinus (invagination of skin)

Once urogenital sinus and paramesonephric ducts fuse, ...

we have a continuous duct system (YAY?)

Cranial vagina, cervix and uterus come from...

paramesonephric ducts (mesoderm)

Epithelial buds in urethra and urogenital sinus make...

urethral and vestibular glands

urethral gland in the female =

the prostate in males

the bulbourethral gland in males =

vestibular gland in females

Support of the female tract is ...

broad ligament (surrounds uterus - supports dorsally and laterally)

In cranial parts, the female gonad and paramesonephric duct are _____

Seperate, they fuse as you go caudally (and rotate a little bit)

In caudal parts, the paramesonephric ducts will ____ and make the _____, _____, and cranial part of ______

fuse body of uterus cervix cranial part of the vagina

Male and female gonads and duct systems originate....

behind the peritoneum (retroperitoneal)

More caudally from the cranial parts in the female, ...

gonadal ridges and paramesonephric ducts move ventrally but do not fuse. There is some rotation starting here (medially)

In the fusion process, the female reproductive tract is sandwiched between....

two layers of peritoneum called the GENITAL FOLD

The genital fold becomes

the broad ligament

Before sex is differentiated in the embryo, mesenchymal cells from the primitive streak will...(2)

move around the cloacal membrane | and form the two cloacal folds

What happens to the cloacal folds? (2)

fuse to make the genital tubercle | also, they subdivide into anal and urogenital folds (with anal and urogenital membranes)

Mesoderm lateral to each urogenital fold will then... (2)

proliferate and elavate making the LABIO-SCROTAL or GENITAL SWELLINGS

What chemical is a potent inducer of female genitalia?

17 beta estradiol (estrogens)

What family of chemicals drives male external genitalia?

androgens, dihydroxytestosterone

Genital tubercle gives rise to...

clitoris

Urogenital folds (don't fuse and) give rise to...

labia

steroid influence of external genitalia in males does...

genital tubercle elongates into the phallus

line of fusion in male genitalia =

scrotal raphe

Urethral groove is.. (male genitalia)

an epithelial cord forming inside the fusing urogenital folds. (The urogenital folds make the lateral boundaries of the urethral plate and the urethral groove is inside that)

Penile urethra results after

the urogenital folds enclose the urethral groove

The urethral plate does not go to the tip, but instead...

an ectodermal invagination wil fuse with the endodermal cells lining the penile urethra.

Before the penile urethra opens at the tip, ...

canalisation needs to happen

Oss penis is

when the glans penis grows and ossifies

Mammary ridges are...

ventral epidermal thickenings that go from axillary region to inguinal region of embryo

Steps in development of mammaries (4)

1. primary buds develop (epidermal tissue moves inward and penetrates mesenchyme (dermis) 2. primary buds branches further into dermis to make Secondary Mammary buds 3. Secondaries continue to increase in length and branch 4. Canalisation so each gland has a lactiferous sinus

Proper alveolar and duct system is constructed and finally finished ...

between puberty and pregnancy and finally during the first trimester of pregnancy

4 levels of opportunity for defects in genital systems

1. chromosomal level 2. gonadal differentiation 3. duct system differentiation 4. development of external genitalia

Turner's syndrome (3)

Gonadal degenesis Only one X (one x must be present for viability) PGCs reach gonad but soon degenerate

Turner's syndrome symptoms (4)

hypoplastic ovary small uterus underdeveloped external genitalia infantile genitalia from lack of gonadal hormones

Turner's syndrome is common in

horses (not as much in humans, pigs, dogs, and cats

Klinefelter's syndrome (2)

XXY karyotype | Found in humans, dogs, and cats

Symptoms of Klinefelter's (2)

embryo develops male gonads, produces male related hormones, seems like a male XX chromosomes drives female genes causing hypoplastic testes and infertility (no spermatogenesis)

Hermaphroditism (2)

Defect is early on | ovarian and testicular tissues present (separate or together (OVOTESTES)

Pseudo-hermaphroditism (2)

common form of intersex | sex is determines by gonads (mostly male)

Hypospadias (3)

urethra opens on ventral surface of penis results from urethral groove not closing in the male Common in some dog breeds

Two other types of genital deformalities... (2)

wrong fusion of uterus giving different types | hypoplasia of testes