They contract to allow ejaculation.
They are responsible for penile erection.
They regulate the temperature of the testes.
They contract to push sperm along the ductus deferens.
The dartos muscle
The bulbospongiosus muscles
Sexually transmitted infections
Nondescent of the testes
A diet high in fat
The bulbourethral glands
The seminal vesicles
That human gonadotropin be synthesized in the first week of the pregnancy
That the female hormones are suppressed during pregnancy
Secretion of male hormones prenatally and lasting into the first few months after birth
The suppression of inhibin
Because some blood contents are toxic to the spermatozoa
Because immature sperm cells lose their motility when they encounter any blood component
Because spermatozoa and developing cells produce surface antigens that are recognized as foreign by the immune system
Actually, the blood-testis barrier has no function.
Half the diploid number with no change in development
Twice the diploid number, and with every succeeding generation, the chromosome number would continue to double and normal development could not occur
Triple the diploid number, and with every succeeding generation, the chromosome number would continue to triple and normal development would not occur
There is no relationship between gametes and somatic cells.
They have the same degree of motility
They have the same number of chromosomes
About the same number of each is produced per month
They are about the same size
Sequence of events in the rete testis
Formation of four haploid cells from a spermatogonium
Formation of a functional sperm by the stripping away of superfluous cytoplasm
Movement of sperm in the female genital tract
Increasing mass of the skeleton
Development of testes as opposed to ovaries
Development of body hair
Lowering of the voice
Of different sexes
Absence of an acrosome
Presence of Y chromosomes in approximately half the sperm
Absence of coiled mitochondria
Presence of two X chromosomes in approximately half the sperm
They move away from the pelvic cavity.
They move close to the pelvic cavity.
Excessive warmth has no effect on the testicles because of their location in the scrotum.
Excessive warmth is actually beneficial in that it speeds up the maturation of sperm.
Deepening of the voice
Growth of the larynx
Increased oiliness of the skin
Growth of the breasts at puberty
Secretory activity of the uterine myometrium
Development of the female secondary sex characteristics
Preparation of the mammary glands for lactation
Contraction of uterine muscles
The sperm midpiece consists of mitochondria spiraled tightly around the contractile filaments of the tail.
The acrosome is produced by the Golgi apparatus and contains hydrolytic enzymes.
They are sluggish in an alkaline environment.
They contain very little cytoplasm or stored nutrients.
Inadequate or nonviable sperm will be produced.
Male sex hormones will not be circulated in the body.
Sperm will have no means of exit from the body.
Inadequate blood supply will retard the development of the testes.
A sympathetic reflex
A parasympathetic reflex
Parasympathetic activation of the bulbourethral glands
Dilation of the veins in the penis