Male Reproductive Physiology

Question 1

The müllerian ducts __ in the male. The indifferent gonad migrates to the ___ to become the ___. The ___ is responsible for pulling the testis into the scrotum during development.

Answer 1

The müllerian ducts regress in the male. The indifferent gonad migrates to the urogenital ridge to become the testicle. The gubernaculum testis is responsible for pulling the testis into the scrotum during development.

Question 2

In humans, interstitial tissue takes up __ of the total testicular volume.

Answer 2

20% to 30%

Question 3

FSH and testosterone play the most important role in the regulation of Sertoli cell function. ABP is made by ___.

Answer 3

Sertoli cell function, sertoli cells

Question 4

At least 65% to 70% of ejaculate volume is derived from the __, with the remainder from the__ (with__) and ___. __ may also contribute a small amount of fluid to the normal ejaculate.

Answer 4

SEMINAL VESICLES

VAS DEFERENS (with sperm)

PROSTATIC SECRETIONS

PERIURETHRAL GLANDS

Question 5

The arterial supply to the human testis and epididymis is derived from three sources: .

Answer 5

INTERNAL SPERMATIC ARTERY

DEFERENTIAL ARTERY

CREMASTERIC ARTERy

Question 6

exogenous testosterone inhibits pituitary production of FSH and LH. Because of negative feedback inhibition that maintains homeostatic balance in the pituitarygonadal axis, exogenous testosterone of any type will cause anterior pituitary production of LH and FSH to fall. This results in azoospermia in most of men on anabolic steroids, but the effect will vary based on the dose, frequency, and duration of the steroid regimen

Answer 6

inhibits

anterior pituitary production of LH and FSH

AZOOSPERMIA

Question 7

Sertoli-Sertoli tight junctions prevent the___ into the ___ from the testicular interstitium. These junctions between Sertoli cells also segregate ___ from meiotic and postmeiotic germ cells and are the structural basis for the ___

Answer 7

Sertoli-Sertoli tight junctions prevent the deep penetration of electron-opaque tracers into the seminiferous epithelium from the testicular interstitium. These junctions between Sertoli cells also segregate premeiotic germ cells (spermatogonia) from meiotic and postmeiotic germ cells and are the structural basis for the “blood-testis” barrier

Question 8

testosterone produces ___ and activates negative feedback on FSH secretion. Prolactin in excess can ___ LH secretion.

Answer 8

testosterone produces Inhibin and activates negative feedback on FSH secretion. Prolactin in excess can downregulate LH secretion.

Question 9

Anatomically, the epididymis is divided into three regions: (3)

On the basis of histologic criteria, each region can be subdivided into distinct zones separated by __

Answer 9

the caput or head, the corpus or body, and the cauda or tail of the epididymis.

TRANSITION SEGMENTS

Question 10

____ and exchange of genetic material is the hallmark of chromosomal recombination during meiosis. This does not occur in mitosis. Two other unique characteristics of meiosis are that ___ during meiosis I, the first cell division, and chromosome numbers in daughter cells are half (haploid) that of mitotic cells.

Answer 10

Crossing over of sister chromatids

homologous chromosomes pair

Question 11

A testosterone peak occurs at approximately __ of age. Another peak occurs earlier, during the __ of gestation and a third peak occurs later at __

Answer 11

2 mos

1st trisem

puberty

Question 12

Studies in men with congenital absence of the vas deferens or epididymal obstruction from vasectomy frequently report ___ in sperm aspirated from the ___epididymis, with ___ __ in the __

Answer 12

Studies in men with congenital absence of the vas deferens or epididymal obstruction from vasectomy frequently report poor motility in sperm aspirated from the distal epididymis, with optimal sperm quality and motility in the proximal epididymis.

Question 13

Type A spermatogonia are the only true stem cell in the testis as they can either self renew or differentiate down the spermatogenic pathway.

Answer 13

TRUE STEM CELL

SELF-RENEW

Question 14

Sperm spend ___ developing in the testis and ___ in the epididymis. Depending on ejaculation frequency, they can also be stored in the ___ from for days to several weeks.

Answer 14

45 to 60 days

2-12 days

cauda epididymis

Question 15

The ___ piece of the sperm is a highly organized segment consisting of helically arranged mitochondria surrounding a set of outer dense fibers and the characteristic ___

Answer 15

The middle piece

9 + 2 microtubular structure of the axoneme.

Question 16

Testosterone is converted to DHT in target tissue by__ Testosterone is produced by the ___, exists mainly in bound forms in plasma, and is mainly regulated by __. Excess prolactin __.

Answer 16

5α-reductase.

endocrine testis

LH

decreases testosterone production.

Question 17

Studies have shown that after sexual stimulation or ejaculation, the contents of the vas deferens are propelled back toward the __, because the ___ of the vas deferens contracts with greater amplitude, frequency, and duration than does the ___.

Answer 17

Studies have shown that after sexual stimulation or ejaculation, the contents of the vas deferens are propelled back toward the cauda epididymis, because the distal portion of the vas deferens contracts with greater amplitude, frequency, and duration than does the proximal portion.

Question 18

Regulation of hypothalamic-pituitary-gonadal (HPG) axis hormones occurs primarily through __

Answer 18

NEGATIVE FEEDBACK

Question 19

The determination of maleness is derived from the __ on the Y chromosome. However, developmental genes such as ___ and __ are considered antitestis genes and can proactively induce female gonadal development.

Answer 19

SRY GENE

WNT4 and DAX1

Question 20

Changes to the HPG axis with paternal age include:

Answer 20

lower testosterone levels, blunted axis feedback, and irregular hormone pulsatility.

Question 21

The testis contains ___ of seminiferous tubules and __ in the young adult.

Answer 21

250 M

700 M leydig tubules

Question 22

__ there are increases in sperm structural chromosomal abnormalities, autosomal dominant mutations, and epigenetic alterations leading to disease in offspring.

Answer 22

With paternal age

Question 23

The epididymis consists of __ with absorptive and secretory function, basal cells derived from macrophages, and contractile cells that __

Answer 23

The epididymis consists of principal cells with absorptive and secretory function, basal cells derived from macrophages, and contractile cells that facilitate sperm transport.

Question 24

During __ , sperm mature by gaining progressive motility and the ability to bind to and penetrate the egg zona pellucida.

Answer 24

epididymal passage

Question 25

Epididymal function is temperature and androgen (mainly DHT) dependent, important considerations for __, __, and __ use.

Answer 25

Epididymal function is temperature and androgen (mainly DHT) dependent, important considerations for cryptorchidism, varicocele, and 5α-reductase use.

Question 26

The vas deferens is of Wolffian (mesonephric) duct origin and serves to transport sperm from the ___ to the __

Answer 26

The vas deferens is of Wolffian (mesonephric) duct origin and serves to transport sperm from the cauda epididymis to the ejaculatory duct during seminal emission.

Question 27

Sperm are ciliated cells that possess a ___ axonemal structure that allows motility.

It is estimated that ___ regulate sperm motility.

Answer 27

9+2

200 - 300 million

Question 28

16. Sperm motility defects, termed __, are common and can be either correctable (nonspecific flagellar anomalies) or genetic (dysplasia of the fibrous sheath).

Answer 28

ciliary dyskinesias,

Question 29

Human sperm mtDNA is a __ that encodes for respiratory-chain–complex proteins and is very susceptible to mutations.

Answer 29

circular, histone- and intron-free DNA ring