1. Hypothalamus→GnRH→ Pituitary→LH→Testes→Testosterone
Males
Hypothalamus→GnRH→ Pituitary→LH→Testes→Testosterone
The level of testosterone is under negative-feedback control: a rising level of testosterone suppresses the release of GnRH from the hypothalamus. This is exactly parallel to the control of estrogen secretion in females.

2. Males need estrogen, too!
In 1994, a man was described who was homozygous for a mutation in the gene encoding the estrogen receptor. A single nonsense mutation had converted a codon (CGA) for arginine early in the protein into a STOP codon (TGA). Thus no complete ER could be synthesized.
This man was extra tall, had osteoporosis and "knock-knees", but was otherwise well. His genetic defect confirms the important role that estrogen has in both sexes for normal bone development.

3. Males
It is not known whether this man (or any of the few other men who have been found with the same disorder) is fertile or not.
However, an article in the 4 December 1997 issue of Nature reports that male mice whose ER gene has been "knocked out" are sterile.

4. Males
Anabolic steroids
A number of synthetic androgens are used for therapeutic purposes. These drugs promote an increase in muscle size with resulting increases in strength and speed. This has made them popular with some athletes (weight lifters, cyclists, runners, swimmers, professional football players).
Usually these athletes (females as well as males) take doses far greater than those used in standard therapy. Such illicit use carries dangers (besides being banned from an event because of a positive drug test): acne, a decrease in libido, and — in males — testicle size and sperm counts to name a few.

5. Genetic abnormalities of gonadal function.
Males
Genetic abnormalities of gonadal function.
Many things can go wrong with sexual development in both males and females; fortunately rarely. only at a few that clearly result from the inheritance of single-gene mutations.
Inherited mutations in both copies of the gene encoding the GnRH receptor result in failure to develop at puberty.
Mutations in the gene encoding the LH receptor prevent normal sexual development in both sexes.

6. Genetic abnormalities of gonadal function.
Males
Genetic abnormalities of gonadal function.
Mutations in the gene encoding the FSH receptor block development of the gonads in both males and females.
Mutations in any of the genes encoding the enzymes for synthesis and metabolism of testosterone interfere with normal sexual function in males.
A similar spectrum of disorders in males can be caused by mutations in the genes encoding the androgen receptor.

7. The ovaries of sexually-mature females secrete:
a mixture of estrogens of which 17β-estradiol is the most abundant (and most potent).
progesterone.

8. Females Estrogens Estrogens are steroids.
primarily responsible for the conversion of girls into sexually-mature women.
development of breasts
further development of the uterus and vagina
broadening of the pelvis
growth of pubic and axillary hair
increase in adipose (fat) tissue
participate in the monthly preparation of the body for a possible pregnancy
participate in pregnancy if it occurs

9. Estrogens also have non-reproductive effects.
Females
Estrogens also have non-reproductive effects.
They antagonize the effects of the parathyroid hormone, minimizing the loss of calcium from bones and thus helping to keep bones strong.
They promote blood clotting.

10. Is important in menstrual cycle and pregnancy
Females
Progesterone
Progesterone is also a steroid. It has many effects in the body, some having nothing to do with sex and reproduction.
Is important in menstrual cycle and pregnancy

11. How estrogens and progesterone achieve their effects
Steroids like estrogens and progesterone are small, hydrophobic molecules that are transported in the blood bound to a serum globulin.
In "target" cells, i.e., cells that change their gene expression in response to the hormone, they bind to receptor proteins located in the cytoplasm and/or nucleus.
The hormone-receptor complex enters the nucleus (if it formed in the cytoplasm) and
binds to specific sequences of DNA, called the estrogen (or progesterone) response elements

12. How estrogens and progesterone achieve their effects
Response elements are located in the promoters of genes.
The hormone-receptor complex acts as a transcription factor (often recruiting other transcription factors to help) which
turns on (sometimes off) transcription of those genes.
Gene expression in the cell produces the response.

13. Regulation of Estrogen and Progesterone
The synthesis and secretion of estrogens is stimulated by follicle-stimulating hormone (FSH), which is, in turn, controlled by the hypothalamic gonadotropin releasing hormone (GnRH).
Hypothalamus→GnRH→ Pituitary→FSH→Follicle→Estrogens

14. Pseudo-hermaphroditism is more common.
Hermaphroditism is a term referring to being of both sexes (intersexual).
True hermaphroditism requires the presence of both ovarian (female) and testicular (male) reproductive tissue and is relatively rare and poorly understood.
Pseudo-hermaphroditism is more common.
From a medical standpoint, hermaphroditism suggests two factors:
ambiguous external genitalia
genitalia that do not match the genetic make-up of the person (example: female genitalia in a genetically male individual)

15. congenital adrenal hyperplasia fetal exposure to sex hormones
The following conditions can produce ambiguous genitalia and hermaphroditism:
congenital adrenal hyperplasia
fetal exposure to sex hormones
testicular feminization syndrome
XY gonadal dysgenesis
XY gonadal agenesis
chromosomal abnormalities
cryptophthalmos
Smith-Lemli-Opitz
4p syndrome
13q syndrome

16. Congenital adrenal hyperplasia refers to a group of inherited disorders relating to the adrenal glands, characterized by a deficiency in the hormones cortisol and aldosterone and an overproduction of androgen. Alternative Names: Adrenogenital syndrome; 21-hydroxylase deficiency

17. Congenital adrenal hyperplasia Causes, incidence, and risk factors:
The different types of adrenogenital syndrome are inherited as autosomal recessive diseases and can affect both boys and girls.
The defect is lack of an enzyme needed by the adrenal gland to make the major steroid hormones of the adrenal cortex: cortisol and aldosterone. Due to the block in synthesis of these hormones, there is abnormal 'feedback' and steroids are 'diverted' to becoming androgens, a form of male sex hormones.

18. Congenital adrenal hyperplasia At puberty, the testes are small.
This causes early appearance of male characteristics. In a newborn girl with this disorder, the clitoris is enlarged with the urethral opening at the base (ambiguous genitalia, often appearing more male-like than female). The internal structures of the reproductive tract (ovaries, uterus, and fallopian tubes) are normal. As she grows older, masculinization of some features takes place, such as deepening of the voice, the appearance of facial hair, and failure to menstruate at puberty.
In a newborn boy no obvious abnormality is present, but long before puberty normally occurs, the child becomes increasingly muscular, the penis enlarges, pubic hair appears, and the voice deepens. Affected males may appear to enter puberty as early as 2-3 years of age.
At puberty, the testes are small.

19. Congenital adrenal hyperplasia
Some forms of congenital adrenal hyperplasia are more severe and cause adrenal crisis in the newborn due to salt wasting. In this salt-losing form of congenital adrenal hyperplasia, newborns develop symptoms shortly after birth. These include vomiting, dehydration, electrolyte changes, and cardiac arrhythmias. Untreated, this condition can lead to death within 1-6 weeks after birth.
About 1 in 10,000 to 18,000 children are born with congenital adrenal hyperplasia.

20. Turner syndrome
A disorder in women caused by a chromosomal defect. This disorder inhibits sexual development and causes infertility. Alternative Names:Bonnevie-Ullrich syndrome; Gonadal dysgenesis; Monosomy X Causes, incidence, and risk factors:Turner syndrome is usually caused by a missing X chromosome. It affects 1 out of 3,000 live births. It is usually sporadic meaning that it is not inherited from a parent.

21. Turner syndrome
Rarely, a parent silently carries rearranged chromosomes that can result in Turner syndrome in a daughter; this is the only situation in which Turner syndrome is inherited.
There are many manifestations of this syndrome, but the main features are short stature, webbing of the skin of the neck, absent or retarded development of secondary sexual characteristics, absence of menstruation, coarctation (narrowing) of the aorta, and abnormalities of the eyes and bones.
The condition is either diagnosed at birth because of the associated anomalies, or at puberty when there is absent or delayed menses and delayed development of normal secondary sexual characteristics.

22. Ambiguous genitalia
A congenital physical abnormality where the outer genitals do not have the typical appearance of either sex.
Considerations:The genetic sex of a child is determined at conception. The egg cell (ovum) contains a chromosome called the X chromosome. Sperm cells contain either an X chromosome or one called the Y chromosome. These determine the child's genetic sex. Normally an infant will inherit ONE PAIR (one from the mother and one from the father) of these "sex chromosomes" (two chromosomes).

23. Ambiguous genitalia
Thus, it is the father who "determines" the genetic sex of the child. An infant who inherits the X chromosome from the father is a genetic female (XX pattern) and one who inherits the Y chromosome is a genetic male (XY pattern). The reproductive organs and genitals associated with "female" or "male" arise from the same initial (fetal) tissue. If the process that causes this fetal tissue to become "male" or "female" is disrupted, ambiguous genitalia can develop.

24. Ambiguous genitalia
Ambiguous genitalia are those in which it is difficult to classify the infant (by physical examination) as male or female. The extent of the ambiguity varies. In very rare instances, the physical appearance may be fully developed as the opposite of the genetic sex (e.g., a genetic male may have normal female appearance). Typical ambiguous genitalia in genetic females include an enlarged clitoris that has the appearance of a small penis. The urethral opening (where urine comes out) can be anywhere along, above, or below the surface of the clitoris, which may be considered normal or common abnormalities of anatomic urethra placement (such as hypospadias, when the urethra is on the underside of the penis, instead of at the tip).

25. Ambiguous genitalia
The labia may be fused, resembling a scrotum. The infant may be thought to be a male with undescended testicles; sometimes a lump of tissue is felt within the fused labia, further making it look like a scrotum with testicles.

26. Ambiguous genitalia
In a genetic male, findings of ambiguous genitalia include a small penis, less than 2 to 3 centimeters (0.8 to 1.2 inches) that may appear to be an enlarged clitoris (the clitoris of a newborn female is normally somewhat enlarged at birth). The urethral opening may be anywhere along, above, or below the penis; it can be placed as low as on the peritoneum, further making the infant appear to be a female. There may be a small scrotum with any degree of separation, resembling labia. Undescended testicles commonly accompany ambiguous genitalia. Uncertain or mistaken sex is not a physical threat to life, but can create social upheaval for the child and the family.

27. Ambiguous genitalia
Common Causes:
pseudohermaphroditism (when the genitalia are of one sex, but some physical characteristics of the other sex are present)
true hermaphrodism (very rare -- both ovarian and testicular tissue is present and the child may have parts of both male and female genitalia)
mixed gonadal dysgenesis (where some cells in the body have only a single X chromosome-->female, and some cells in the body have XY chromosomes-->male. This syndrome is variable, and depends on which cells are female, which cells are male, and what percent of each there are

28. chromosomal abnormalities including
Ambiguous genitalia
Common Causes:
congenital adrenal hyperplasia (several forms, but the most common form causes the genetic female to appear male. Male infants with the most common form appear normal at birth, but may show premature sexual development as early as 6 months of age) -- many states test for this as part of the newborn screen (the blood test your baby has at hours of life)
chromosomal abnormalities including

29. Ambiguous genitalia
Common Causes:
Klinefelter's syndrome (XXY--male, usually has small testes; causes infertility; may be associated with learning defects or mental retardation; affects 1/500-1/1000 live male births)
Turner's syndrome (XO--female; usually does not cause ambiguous genitalia (usually looks female at birth), but may have webbed neck, swelling of the hands and feet and other characteristic physical findings at birth; may not be diagnosed until later in life when sexual maturation does not take place; infertile)

30. Ambiguous genitalia
Common Causes:
maternal ingestion of certain medications (particularly androgenic steroids) -- may make a genetic female look more male
lack of production of specific hormones, causing the embryo to develop with a female body type regardless of genetic sex
lack of testosterone cellular receptors (so even if the body makes the hormones needed to develop into a physical male, the body is unable to respond to those hormones, and therefore, a female body-type is the result even if the genetic sex is male)

31. Puberty-Time to Change When your body reaches a certain age, your brain releases GnRH that starts the changes of puberty. When GnRH reaches the pituitary gland, this gland releases into the bloodstream two more puberty hormones: LH and FSH.
Guys and girls have both of these hormones in their bodies. And depending on whether you're a guy or a girl, these hormones go to work on different parts of the body.

32. Puberty-Time to Change Guys- these hormones travel through the blood and give the testes the signal to begin the production of testosterone and sperm.
Testosterone is the hormone that causes most of the changes in a guy's body during puberty. Sperm cells must be produced for men to reproduce.
In girls, FSH and LH target the ovaries, which contain eggs that have been there since birth. The hormones stimulate the ovaries to begin producing another hormone called estrogen. Estrogen, along with FSH and LH, causes a girl's body to mature and prepares her for pregnancy.