05 - Examples of Intersexuality in Domestic Animals

Question 1

(Cattle Freemartinism)

1. This is the best known syndrome causing sexual derangement in cow
2. It affects female calves in twin pregnancies where the co-twin is what?
3. What percentage of female calves from such pregnancies are affected?
4. This disorder requires what (think vascularly)?

Answer 1

2. male
3. over 90%
4. vascular anastamosis of chorioallantoic vessels between the two placentas

Question 2

(Freemartinism)

1. What does female ovary look like? germ cells?
2. Ovary may have a what?
3. How are mullerian ducts, oviducts, uterus affected?
4. From the urogential sinus there is a what?

Answer 2

1. rudimentary ovary (may have some testicle tissue), few or now germ cells
2. tunica albuginea (similar to covering of normal testicle)
3. mullerian ducts variably regressed, ovidcuts more regressed, rudimentary uterus
4. small vulva and short blind-ending vagina (the Mullerian duct and urogential sinus derivatives have not joined together)

Question 3

(Freemartinism)

1. How much is external genitatlia masulinized?
2. May be testosterone dependent growth of what?

Answer 3

1. only slightly, sometimes clitoris is enlarged
2. Wolffian duct derivatives, seminal vesicles, epididymies, prostate

Question 4

(freemartinism)

(this is general process)

1. In most twin pregnancies anastomosis of blood vessels between two placentas occurs when?
2. Indifferent gonads of co-twinned bull start to develop as testes when?
3. female gonads are similar to normal presumptive ovaries until when?
4. the male is producing MIS from about day 50.. so what starts happening at this time?

Answer 4

1. 28-30 days of gestation (gestation in cattle is 280 days)
2. 40 days
3. day 50 of gestation
4. his Mullerian ducts have commenced regression

Question 5

(freemartinism)

(cont)

1. After day female the female gonads are inhibited by what? What does this cause to happen?

Does mullerian regression occur at same or differenct times in male/female?

2. From day 60-80 days remale gonadal regression and loss of germ cells continues… what may form?

Answer 5

1. MIS transferred by anastomosed vessels from the male; causes gonadal growth to cease, stop germ cell multiplicaton, starts Mullerian duct regression

simultaneous

2. a tunica albuginea

Question 6

(freemartinism)

(cont)

1. From 90-100 days (follicle formation in normal female) what is complete?
2. May get development of what and what in ovarian medulla/rete region (~50% of cases); from what?
3. Can there be Leydig cell formation?
4. These sex-reversed gonads produce testosterone instead of estrogen due to what?

Answer 6

1. ovarian stunting
2. Sertoli and seminiferous tubules from MIS prodcution now from female (but damage has already been done from MIS from male)
3. yes… after 3 months
4. inhibition of the aromatase enzyme.

Question 7

(freemartinism)

(effects on the male co-twin)

1. There is also a passage of cells across the placental anastomoses, germ cells and blood cell precursors are known to migrate.

Resultant calves, both male and female, are what with regards to blood?

2. How do these bull calves compare to normal males?

Answer 7

1. blood-cell chimeras
2. poorer fertility, poor quality semen, low non-return rates

Question 8

(freemartinism)

1. also reported in what other animals?
2. incidence in sheep appears to be increasing with increaseing use of what?
3. does it happen in marmosets of humans?

Answer 8

1. sheep, goats, and pigs
2. high fecnudity breeds (risk is high for litters of 4 or more)
3. no (despite extensive vascular anastomoses)

Question 9

(goats)

1. intersex conditions are commonly reported in goats… best described is associated with polled animals
2. The Polled/Intersex syndrome (PIS) occurins in European Dairy breeds (Saanen, Toggenburg and Alpine) and appears to be the most common form of intersex in domestic animals
3. The affecte animals are sex revesred females being what?
4. Phenotypically they are mostly female at birth but on attaining puberty the become what?

Answer 9

3. XX genetically but having testes
4. larger than normal, head becomes masculine, erect hair on neck, clitoris enlarges (may be visible externally)

develop buck odor, small teats, and have agressive male type libido

Question 10

(goats)

(Polled/intersex cont)

1. what genetic makeup is it?

located where on chromosome?

2. Do they affected animals have Sry?

but have a deletion where?

Answer 10

1. autosomal dominant (P)

close to intersex region (recessive) on goat chromosome I

2. no

of 11.7 kb DNA from chromosome I (currently referred to as PIS -/- because as it is recessive they have a deltion on both copies of chromosome I

Question 11

(goats)

(Polled/intersex syndrome)

(How they think it works)

In normal XX (female) animals (XX PIS+/+ or XX PIS
+/-) PIS is a promotor region which up-regulates transcription of nearby genes PISRT1, FOXL2 and PFOXic. PISRT1 (PIS-regulated transcript 1) inhibits SOX9 (which is critical for testis formation) and thus prevents formation of a testicle -i.e. PISRT1 is an anti-testis gene . FOXL2 and PFOXic are pro-ovarian genes. (So there are anti-testis and pro-ovarian genes close together)

1. In an affected XX animal, with deletions of PIS on both copies of chromosome I (XX PIS -/-), while these genes are still present (they are outside region of deletion) they don’t get up-regulated… why?

Answer 11

1. because their promoter is missing (SOX9 is not inhibited so a testicle forms)

Question 12

(goats)

(Polled/intersex syndrome)

However, being homozygous for the polled gene also impacts bucks….

1. Homozygous polled bucks tend to become what? due to what?

this leads ultimately to what?

Answer 12

1. sterile; due to blockage of the epididmal duct in the caput epididymis (resulting from poor differentiation of the duct)

This leads in turn to palpable sperm granuloma formation