Hy Embryology 10 Part 3

Front 1

What is intersexuality?

Back 1

Because the early embryo goes through an indifferent stage, events may occur whereby a fetus does not progress toward either of the two usual phenotypes but gets caught in an intermediate stage known as intersexuality

Front 2

How is intersexuality classified?

Back 2

Intersexuality is classified according to the histological appearance of the gonad and abiguous genitalia

Front 3

Describe true intersexuality

Back 3

1. True intersexuality occurs when an individuals has both ovarian and testicular tissue (ovotestes) histologically, ambiguous genitalia, and a 46,XX genotype.

2. True intersexuality is a rare conditions whose cause is poorly understood

Front 4

Describe female pseudointersexuality (FP)

Back 4

Female pseudointersexuality (FP) occurs when an individuals has only ovarian tissue histologically and masculinization of the female external genitalia

Front 5

What is the genotype of individuals with female pseudointersexuality?

Back 5

46,XX

Front 6

Female pseudointersexuality is most often observed clinically with what?

Back 6

A condition in which the fetus produces an excess of androgens [eg, congenital adrenal hyperplasia (CAH)]

Front 7

Describe the cause of congenital adrenal hyperplasia

Back 7

CAH is caused most commonly by mutations in genes for enzymes involves in adrenocortical steroid biosynthesis (eg, 21-hydroxylase deficiency, 11β-hydroxylase deficiency)

Front 8

Describe 21-hydroxylase deficiency

Back 8

1. 90% of all cases of congenital adrenal hyperplasia

2. There is virtually no synthesis of cortisol or aldosterone so that intermediates are funneled into androgen biosynthesis, thereby elevating androgen levels

3. The elevated levels of androgens leads to masculinzation of the female fetus

Front 9

What are the clinical findings of female pseudointersexuality?

Back 9

1. Mild clitoral enlargement
2. Complete labioscrotal fusion with a phalloid organ
3. Macrogenitosomia (in the male fetus)

Front 10

Describe salt, water, and potassium levels in a patients with female pseudointersexuality

Back 10

1. Because cortisol cannot be synthesized, negative feedback to the adenohypophysis does not occur, so adrenocorticotropic hormone (ACTH) continues to stimulate the adrenal cortex, resulting in adrenal hyperplasia

2. Because aldosterone cannot be synthesitzed, teh patients presents with hyponatremia ("salt-wasting") with accompanying dehydration and hyperkalemia.

Front 11

Describe the treatment for female pseudointersexuality

Back 11

Immediate infusion of IV saline and long term steroid hormone replacement, both cortisol and mineralocorticoids (9α-fludrocortisone)

Front 12

Describe Male Pseudointersexuality (MP)

Back 12

Male pseudointersexuality occurs when an individuals has only testicular tissue histologically and various stages of stunted development of the male external genitalia

Front 13

Describe the genotype of patients with Male Pseudointersexuality (MP)

Back 13

46,XY

Front 14

How is Male Pseudointersexuality (MP) most often observed clinically?

Back 14

In association with a condition in which the fetus produces a lack of androgens (and MIF)

Front 15

What is the cause of male pseudointersexuality

Back 15

This is caused most commonly by mutations in genes for androgen steroid biosynthesis (eg, 5α-reductase 2 deficiency of 17β-hydroxysteroid dehydrogenase (HSD) deficiency)

Front 16

Describe the normal function of 5α-reductase 2

Back 16

Normally 5α-reductase 2 catalyzes the converstion of testosterone (T) to dihydrotestosterone (DHT)

Front 17

Describe the normal function of 17β-hydroxysteroid dehydrogenase 3

Back 17

Normally 17β-hydroxysteroid dehydrogenase 3 catalyzes the converstion of androstenedione to testosterone

Front 18

What is diagnostic of 5α-reductase 2 deficiency?

Back 18

An elevated T:DHT ratio

Front 19

What are the consequences of reduced androgens in male pseudointersexuality?

Back 19

The reduced levels of androgens lead to feminization of a male fetus

Front 20

What are the clinical findings in a patient with male pseudointersexuality?

Back 20

1. Underdevelopment of the penis, scrotum (microphallus, hypospadias, and bifid scrotum), and prostate gland

2. The epididymis, ductus deferens, seminal vesicle, and ejaculatory duct are normal

Front 21

Describe what occurs when a patient with male pseudointersexuality undergoes puberty

Back 21

At puberty, these patients demonstrate striking virilization

Front 22

Describe complete androgen insensitivity

Back 22

Occurs when a fetus with a 46,XY genotype develops testes and female external genitalia with a rudimentary vaginal uterus and uterine tubes are generally absent

Front 23

In patients with complete androgen insensitivity, where are the testes found?

Back 23

The testes may be found in the labia majora and are surgically removed to circumvent malignant tumor formation

Front 24

Describe how individuals with complete androgen insensitivity present?

Back 24

These individuals present as normal-appearing females, and their psychosocial orientation is female despite their genotype

Front 25

What is the most common cause of complete androgen insensitivity?

Back 25

A mutation in the gene for the androgen receptor

Front 26

What do the gonads from the indifferent embryo develop into?

Back 26

Adult Female: Ovary, ovarian follicles, rete ovarii

Adult Male: Testes, seminiferous tubules, tubuli recti, rete testes, Leydig cells, Sertoli cells

Front 27

What do the paramesonephric ducts from the indifferent embryo develop into?

Back 27

Adult Female: Uterine tubes, uterus, cervix, superior 1/3 of the vagina. Possibly hydatid of Morgagni

Adult Male: Nothing usually, sometimes appendix testes

Front 28

What do the mesonephric ducts from the indifferent embryo develop into?

Back 28

Adult female: Nothing usually, sometimes the Appendix vesiculosa, Gartner's duct

Adult male: Epididymis, ductus deferens, seminal vesicle, ejaculatory duct

Front 29

What do the mesonephric tubules from the indifferent embryo develop into?

Back 29

Adult female: Nothing usually, sometimes the epoophoron, and paroophoron

Adult male: Efferent ductules and sometimes the paradidymis

Front 30

What does the phallus from the indifferent embryo develop into?

Back 30

Adult female: Glans clitoris, corpora cavernosa, clitoris, vestibular bulbs

Adult male: Glans penis, corpora cavernosa penis, corpus spongiosum

Front 31

What do the urogenital folds from the indifferent embryo develop into?

Back 31

Adult female: Labia minora

Adult male: Ventral aspect of penis

Front 32

What do the labioscrotal swellings from the indifferent embryo develop into?

Back 32

Adult female: Labia majora, mons pubis

Adult male: Scrotum

Front 33

What does the gubernaculum from the indifferent embryo develop into?

Back 33

Adult female: Ovarian ligament, round ligament of uterus

Adult male: Gubernaculum testes

Front 34

What does the processus vaginalis from the indifferent embryo develop into?

Back 34

Adult female: Nothing

Adult male: Tunica vaginalis