The Regular Menstrual Period The critical point about this category is that the period is regular from month to month, beginning like clockwork

 

The condition may be due to an adrenal tumor or to

excessive stimulation of the adrenal gland by ACTH

(adrenocorticotropic hormone) from the pituitary.

If ACTH is high, either the pituitary is overactive or

an ACTH-secreting pituitary tumor is present (called

Cushing’s disease). Elevated adrenal androgens suppress

LH and FSH production and spermatogenesis. Cortisone

replacement therapy will reduce cortisol levels and

restore natural LH, FSH, and sperm production. If a tumor

is present, surgery and/or radiation therapy is required.

Germ Cell Aplasia (Sertoli Cell Only)

Germ cell aplasia (Sertoli cell only) is an inherited

condition. Testes have normal Leydig cells, no germ

cells. Because their Leydig cells continue to produce

testosterone, these men remain virile, but they cannot

produce sperm. Germ cell aplasia can also be caused

by exposure to large doses of radiation and prolonged

exposure to toxic substances.

Testicular Enzyme Defects

Testicular enzyme defects prevent the testes from

responding normally to hormonal stimulation. These rare

genetic defects can cause multiple genital abnormalities,

incomplete virilization, small testes, and low or no sperm

production. The LH and FSH will both be high, since,

the brain is doing its best to stimulate the unresponsive

testicles.

FEMALE FERTILITY

The Five Female Fertility Factors

Fertility Factor—1: Ovulation

Any woman complaining of very heavy menstrual flow,

very light menstrual flow, no menstrual flow, irregular

cycles, breast discharge, or scanty or overabundant body

hair growth is telling that she may not be ovulating. This

may be due to an intrinsic malfunction of her reproductive

organs or hormones or to a systemic disease causing other

body chemistry problems.

Fertility Factor—2: Sperm-Mucus Interaction

Normally, the cervical mucus forms an impervious plug

that keeps foreign materials, including sperm, from

entering the uterus. Once each month, responding to

estrogen, the cervical mucus becomes clear, thin, and

stringy so sperm can swim through the cervix into the

uterus.

Fertility Factor—3: Fertilization

Fertilization depends on the sperm’s ability to penetrate

the outer layers of the egg and transfer its genetic

information.

Fertility Factor—4: Tubal Factor

Other clues uncovered during the physical examination

may point to transport problems. Abdominal adhesions

can prevent the egg from entering the fallopian tube as well

as impede its passage through the tube. Endometriosis can

cause adhesions and impair ovulation.

Depending on their size and location, fibroids and

ovarian cysts can also interfere with egg transport. These

conditions will usually respond to surgery.

Fertility Factor—5: Embryo Implantation

The egg or (if the egg is fertilized) the embryo has to

successfully implant in the woman’s uterus. Sometimes,

during the physical examination one can detect obvious

causes for miscarriage such as congenitally malformed

reproductive organs, an abnormally shaped cervix or a

cervix distorted by previous surgical procedures.

Female Hormone System

What is Ovulation?

Ovulation is a fascinating harmony performed by several

different “players”—the hypothalamus, pituitary gland,

and ovary. The hypothalamus maintains the hormonal

“tempo” by regularly pulsing GnRH (gonadotropic-releasing hormone). These pulses stimulate the pituitary gland

to produce LH (luteinizing hormone) and FSH (folliclestimulating hormone).

The pituitary gland plays the chorus—a pattern repeated

from month to month in a beautifully precise rhythm.

Each month the pituitary secretes FSH to stimulate the

development and growth of over one thousand eggs. This

phase in the ovulation cycle is known as the follicular phase.

At puberty, a woman has about half a million primitive

germ cells. Only four or five hundred, however, will ever

reach maturity. Due to some mysterious mechanism,

764 Concise Book of Medical Laboratory Technology: Methods and Interpretations which we do not yet understand, usually each month only

one of the thousand developing eggs becomes dominant

and grows to maturity. This egg, or ovum, is cradled within

the ovary in a tiny, fluid-filled capsule called the follicle.

During the follicular phase of the cycle, LH acts on the

ovary’s theca cells to initiate estrogen production by the

granulosa cells. The estrogen makes the follicle even more

responsive to FSH, which further stimulates follicular

growth and development of the egg. As the follicle

expands toward the surface of the ovary, the egg increases

in size nearly forty times. The ovary tells the pituitary

when it needs more or less FSH to finish the job of egg

maturation by making a feedback hormone called inhibin

(folliculostatin).

Shortly before ovulation, the genetic material (nucleus)

in the egg divides (meiosis) to half the number of

chromosomes in the cell. If the egg is fertilized, a second

meiotic division leaves the ovum with twenty-three

chromosomes—a perfect complement to the sperm’s

twenty-three. To form an egg, the female germinal cell

divides twice, as does the male germinal cell. During

female germ cell divisions, however, the “surviving” ovum

jealously hoards the bulk of cellular material (nutrients)

and casts off the excess genetic material (polar bodies).

The egg or (if the egg is fertilized) the embryo survives on

these nutrients until the embryo successfully implants in

the woman’s uterus.

Estrogen also stimulates the uterine lining

(endometrium) to become thick, lush, and filled with

nutrients for the embryo. The cervical mucus responds to

elevated estrogen by becoming clear, watery, and stringy.

Normally, impervious to sperm, at midcycle the mucus

welcomes the sperm and promises easy passage toward

the egg.

When a woman’s estrogen level peaks at midcycle, the

pituitary “knows” that the egg is ready to embark on its

journey. The pituitary responds to the estrogen peak by

producing a surge of LH, which releases the egg within

18 to 36 hours. The outer wall of the ovary dissolves

away from the bulging follicle; and within 2 to 3 minutes,

the ovum escapes into the woman’s abdominal cavity.

Surrounded by a sticky protective layer of cells (cumulus

oophorus), the egg gently floats toward the fallopian tube.

The expelled follicular fluid stimulates the fimbriated end

of the fallopian tube to reach toward the ovum, grasp the

ovary, and vacuum up the egg. The muscles and tiny hairs

(cilia) lining the fallopian tube gently coax the egg on its 3 to

4 days journey through the narrow passage. For conception

to occur during this cycle, the sperm must fertilize the egg

in the fallopian tube within 12 hours of ovulation.

During the egg’s journey, the ruptured follicle begins

an amazing transformation into the corpus luteum.

Stimulated by LH from the pituitary gland, this yellowpigmented, glandular, ovarian structure enlarges to make

up nearly a third of the ovary. During the luteal phase

(latter half of the cycle), the corpus luteum produces

progesterone, a hormone that prepares the uterine lining

for implantation of the embryo. Progesterone also acts

on your body’s temperature-regulating mechanism by

raising basal body temperature (BBT) approximately

one-half degree. Thus, shortly after ovulation, a woman

will see a rise on her BBT chart. If fertilization does not

take place, the corpus luteum deteriorates. Estrogen and

progesterone levels decline rapidly in the week or so

prior to menstruation. Deprived of these hormones, the

endometrium atrophies and menstrual flow begins. At the

site of the original follicle, the corpus luteum degenerates

and leaves a minute piece of scar tissue as a reminder

of its brief existence. If fertilization takes place, a corpus

luteum of pregnancy forms to maintain the uterine lining

(endometrial bed) and support the implanted fertilized

ovum (conceptus) (Fig. 24.10).

FIG. 24.10: Female hormone system

The Endocrine System 765

The hypothalamus, pituitary, and ovary must all work

in perfect harmony. When they do not, the most obvious

symptom is abnormal menses.

What Makes One have a Period?

Normally, each month estrogen and progesterone stimulate

the growth of the uterine lining. When the progesteroneproducing corpus luteum deteriorates toward the end of

the cycle, “progesterone withdrawal bleeding” occurs: you

have a period. Waves of vasoconstriction (blood vessel

spasms) restrict the blood supply to the endometrium

and thus provoke the onset of menses. At the conclusion

of menses, clotting factors seal off exposed bleeding sites,

and resumed estrogen production begins restoring the

endometrium.

Clues from the Menstrual History

The Three Types of Menstrual Patterns

The Regular Menstrual Period

The critical point about this category is that the period is

regular from month to month, beginning like clockwork

every 25 days or every 35 days, for example. If the periods

are regular, then she is probably ovulating. The consistently

irregular menstrual cycle, however, where one month she

begins menstruating after 25 days, the next month after 34,

and the next in thirty, may indicate that she has a fertility

problem. If a woman reports a regular menstrual history,