Reproduction and sex Medical Assignment Help

Normal physiology of the female and male reproductive systems will first be considered, followed by their common disorders.

Delayed puberty

Over 95% of children show signs of pubertal development by age 14 years. In its absence, investigation should begin by age 15 years. Causes of hypogonadism (below) are clearly relevant but most cases represent constitutional delay:
IN CONSTITUTIONAL DELAY, pubertal development, bone age and stature should be in parallel. A family history may confirm that other family members did the same.
IN BOYS, testicular volume >5 rnl indicates the onset of puberty. A rising serum testosterone is an earlier clue. IN GIRLS, the breast bud is the first sign. Ultrasound allows accurate assessment of ovarian and uterine development.
BASAL LH/F SH LEVELS may identify the site of a defect, and LHRH tests can indicate the stage of early puberty.
IF ANY PROGRESSION AT ALL IS EVIDENT CLINICALLY, observation is usually indicated.
LOW-DOSE SHORT-TERM SEX HORMONE THERAPY to induce puberty is possible when delay is great and problems are serious (e.g. severe teasing at school). Specialist assessment is advisable. Until 8 weeks the sexes share a common development, with a primitive genital tract including the Wolffian and Miillerian ducts. There are additionally a primitive perineum and primitive gonads. In the presence of a Y chromosome the potential testis develops while the ovary regresses. In the absence of a Y chromosome, the potential ovary develops and related ducts form a uterus and the upper vagina. Production of Miillerian inhibitory factor from the early ‘testis’ produces atrophy of the Mullerian duct, while, under the influence of testosterone and dihydrotestosterone, the Wolffian duct differentiates into an epididymus, vas deferens, seminal vesicles and prostate. Androgens induce transformation of the perineum to include a penis, penile urethra and scrotum containing the testes, which descend in response to androgenic stimulation. At birth testicular volume is 0.5-1 mI. Definitions Relevant terminology.

PHYSIOLOGY

The male

An outline of the hypothalamic-pituitary-testicular axis.
1 Pulses of LHRH (GnRH) are released from the hypothalamus and stimulate LH and FSH release from the pituitary.
2 LH stimulates testosterone production from Leydig cells of the testis.
3 Testosterone acts systemically to produce male secondary sexual characteristics, anabolism and the maintenance of libido. It also acts locally within the testis to aid spermatogenesis. Both testosterone and oestrogen circulate largely bound to sex hormone-binding globulin (SHBG).
4 FSH stimulates the Sertoli cells in the seminiferous tubules to produce mature sperm and the feedback hormone inhibin.
S Testosterone feeds back on the hypothalamus/pituitary to inhibit LHRH secretion.
6 Inhibin causes feedback on the pituitary to decrease FSH secretion.
The secondary sexual characteristics of the male for which testosterone is necessary are the growth of pubic, axillary and facial hair, enlargement of the external genitalia, deepening of the voice, sebum secretion, muscle growth and frontal balding.

(a) Male and (b) female hypothalamic-pituitarygonadal axes.

(a) Male and (b) female hypothalamic-pituitarygonadal axes.

Definitions in reproductive medicine.

Definitions in reproductive medicine.

The female

The female situation is more complex.
1 In the adult female, higher brain centres impose a menstrual cycle of 28 days upon the activity of hypothalamic GnRH.
2 Pulses of GnRH, at about 2-hour intervals, stimulate release of pituitary LH and FSH.
3 LH stimulates ovarian androgen production.
4 FSH stimulates follicular development and arornatase activity (an enzyme required to convert ovarian androgens to oestrogens). FSH also stimulates inhibin from ovarian stromal cells. Inhibin, in turn, inhibits FSH release.
S Although many follicles are ‘recruited’ for development in early folliculogenesis, by day 8-10 a ‘leading’ follicle is selected for development into a mature Graafian follicle.
6 Oestrogens show a double feedback action on the pituitary, initially inhibiting gonadotrophin secretion (negative feedback), but later high-level exposure results in increased GnRH secretion and increased LH sensitivity to GnRH (positive feedback), which leads to the mid-cycle LH surge inducing ovulation from the leading follicle.
7 The follicle then differentiates into a corpus luteum, which secretes both progesterone and oestradiol during the second half of the cycle (luteal phase).
8 Oestrogen initially and then progesterone cause uterine endometrial proliferation in preparation for possible implantation; if implantation does not occur, the corpus luteum regresses and progesterone secretion and inhibin levels fall allowing increased GnRH and FSH secretion so that the endometrium is shed (menstruation).
9 If implantation and pregnancy follow, human chorionic gonadotrophin (HCG) production from the corpus luteum maintains corpus luteum function till 10- 12 weeks, by which time the placenta will be making sufficient oestrogens and progesterone to support itself.
10 Oestrogen circulates largely bound to SHBG .
Oestrogens also induce secondary sexual characteristics, especially development of the breast and nipples, vaginal and vulval growth and pubic hair development. They also induce growth and maturation of the uterus and tubes. They do not, however, usually increase breast size in other circumstances.

Hormonal and follicular changes during the normal menstrual cycle.

Hormonal and follicular changes during the normal menstrual cycle.

Puberty

The mechanisms initiating puberty remain poorly understood but are thought to result from withdrawal of central inhibition of GnRH release. LH and FSH are both low in the prepubertal child. In early puberty, FSH begins to rise first, initially in nocturnal pulses; this is followed by a rise in LH with a subsequent increase in testosterone/oestrogen levels. The milestones of puberty in the two sexes.
In boys, pubertal changes begin between 10 and 14 years and are complete between IS and 17 years. The genitalia develop, testes enlarge and the area of pubic hair increases. Peak height velocity is reached between ages 12 and 17 years during stage 4 of testicular development. Full spermatogenesis occurs comparatively late. In girls, even ts start a year earlier. Breast bud enlargement begins at ages 9-13 years and continues to 12-18 years. Pubic hair growth commences at ages 9-14 years and is completed at 12-16 years. Menarche occurs relatively late (age II-IS years) but peak height velocity is reached much earlier than in boys (age 10-13 years). Growth is completed earlier than in boys.

The age of development of features of puberty.

The age of development of
features of puberty.

Precocious puberty

Development of menarche (girls) or secondary sexual characteristics (boys) before the age of 9 years is premature, and may take the following forms: IDIOPATHIC (TRUE) PRECOCITY, commoner in girls. This is a diagnosis of exclusion with no apparent cause for premature breast or pubic hair development, and an early growth spurt; it may be normal and run in families. Treatment has been with cyproterone acetate, an anti-androgen with progestational activity, but longacting LHRH analogues causing suppression of gonadotrophin release with reduced sex hormone production have largely superseded cyproterone: these may be given by nasal spray, by subcutaneous injection or preferably by implant.
CEREBRAL PRECOCITY. Many causes of hypothalamic disease, especially tumours, may present in this way. In boys this must be rigorously excluded.
FORBES-ALBRIGHT SYNDROME, usually in girls, with precocity, polyostotic fibrous dysplasia and skin pigmentation (cafe-au-lait).
PREMATURE THELARCHE is early breast development alone, usually transient between ages 2 and 4 years. It may regress or persist till puberty.
PREMATURE ADRENARCHE is early development of pubic hair without significant other changes, usually after age 5 years and commoner in girls.

 Delayed puberty

Over 95% of children show signs of pubertal development by age 14 years. In its absence, investigation should begin by age 15 years. Causes of hypogonadism are clearly relevant but most cases represent constitutional delay:
IN CONSTITUTIONAL DELAY, pubertal development, bone age and stature should be in parallel. A family history may confirm that other family members did the same.
IN BOYS, testicular volume >5 rnl indicates the onset of puberty. A rising serum testosterone is an earlier clue. IN GIRLS, the breast bud is the first sign. Ultrasound allows accurate assessment of ovarian and uterine development.
BASAL LH/F SH LEVELS may identify the site of a defect, and LHRH tests can indicate the stage of early puberty.
IF ANY PROGRESSION AT ALL IS EVIDENT CLINICALLY, observation is usually indicated.
LOW-DOSE SHORT-TERM SEX HORMONE THERAPY to induce puberty is possible when delay is great and problems are serious (e.g. severe teasing at school). Specialist assessment is advisable.

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Endocrinology.

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