HC 1

Question 1

Spermatozoa travel from

Answer 1

Spermatozoa travel from testis within
epididymis; to ductus deferens; to
ejaculatory duct and penile urethra.
Fluids are secreted from the seminal
vesicles, the prostate gland, and the
bulbourethal glands

Question 2

How does regulating the temperature happen

Answer 2

Cremaster and dartos muscles
relax/contract to regulate
temperature

Question 3

Connective tissue

Answer 3

Supports blood and lymphatic vessels, drains the efferent ductules, which transport spermatozoa to ependymis

Question 4

Seminiferous tubules

Answer 4

Spermatozoa production, via rete testis to ependymis. Contain spermatogonia
* Stem cells involved in spermatogenesis
* Production of spermatozoa
* Contain sustentacular cells
* Sustain and promote development of sperm

Question 5

Somatic cells divide only by

Answer 5

mitosis

Question 6

Germ cells, and gametes divide by

Answer 6

meiosis, haploid cells are produced from
diploid cells. Male germ cells: known as spermatogonia. Some of them continually duplicate themselves (via
mitosis; type A) throughout a male’s reproductive life
(maintain population) = self renewal; symmetric division
* Other spermatogonia (type B) are destined to develop
into sperm (via meiosis) => when different fates; asymmetric division

The products of meiosis
are not identical to the
parent cell or to each other

Question 7

Recombination occurs in
the

Answer 7

first steps, this creates 4
different copies of each
chromosome every time
meiosis occurs

Question 8

Segregation and Independent Assortment

Answer 8

Chromosomes are randomly
distributed and hence are
segregated to daughter cells in
meiosis 1 (always a complete set)
* Alleles on different pairs of
homologous chromosomes are
again distributed independently
in meiosis 2

Question 8

Recombination

Answer 8

• Homologous chromosomes lie adjacent in meiosis I
• One chromosome segment exchanges positions with its homologous counterpart
• Genetic information is exchanged between homologous chromosomes
• Two recombinant chromosomes are formed
• One average minimal 1 recombination event per chromosome

Question 9

Spermatogenesis steps (3)

Answer 9

1. mitosis, spermatogonia are stem cells in the seminiferous tubules that under go cell divisions throughout adult life, some differentiate into primary spermatocytes
2. Meiosis, primary spermatocytes then undergo meiotic divisions that produce spermatids
3. Spermiogenesis, spermatids differentiate into physically mature sperm

Question 10

Mitosis of spermatogonium, 1. Stem cells (spermatogonia)

Answer 10

1. Stem cells (spermatogonia) divide
   by mitosis:
   * to produce 2 diploid daughter cells:
   * 1 remains as spermatogonium
   * second differentiates into
   primary spermatocyte
    Occurs throughout adult life during puberty
    1 daughter cell from each division remains in place for future division

Question 11

2. Primary spermatocytes:

Answer 11

• begin meiosis I
• form secondary
  spermatocytes (meiosis I finished)

Question 12

2. Secondary spermatocytes:

Answer 12

differentiate into spermatids (meiosis II finished, but immature gametes)

Question 13

4 Spermatids:

Answer 13

• differentiate into spermatozoa = Spermiogenesis

Question 14

5. Spermatozoa:

Answer 14

• lose contact with wall of
  seminiferous tubule
• enter into fluid of lumen

Question 15

In spermatogenesis, which cells are diploid

Answer 15

2n are spermatogonia, stem cell which undergo mitosis
and primary spermatocytes, these enter meiosis

Question 16

Which cells in spermatogenesis are haploid

Answer 16

n
Secondary spermatocytes, formed after meiosis I, half the original chromosome number
Spermatids, after meiosis II, the secondary spermatocytes divide again
Spermatozoa, mature sperm cells derived from spermatids

Question 17

SpermiOgenesis

Answer 17

*Is the last step of spermatogenesis
*Each spermatid matures into
1 spermatozoon (sperm):
–sustentacular cells
phagocytose shed cytoplasm
and provide nutrient

Question 18

Acrosomal vesicle:

Answer 18

*Made of fused saccules of spermatid’s Golgi
apparatus & peroxisome
*Forms acrosomal cap of spermatozoon
*Contains degrading enzyme

Question 19

Anatomy of a Spermatozoon

Answer 19

1. Head
   Contains nucleus and chromosomes
   Acrosomal cap at tip of head
   * Is a membranous compartment
   * Contains enzymes essential to fertilization
   * Formed out of Golgi apparatus
2. Neck
   Contains centrioles (anterior: mitotic spindle;
   posterior: continuous microtubules for
   movement of flagellum)
3. Middle piece
   Contains mitochondria (= energy!) of original
   spermatid
4. Tail
   * Is a whip-like organelle
   * Moves cell from 1 place to another
   * Has complex, corkscrew motion

Question 20

Sustentacular cells

Answer 20

• surround and
  enfold spermatids
• phagocytize
  cytoplasm shed by
  developing
  spermatids
• provide nutrients
  and chemical
  stimuli (o.a. ABP)
  for development

Question 21

6 Major Functions of Sustentacular Cells

Answer 21

1. Maintain blood–testis barrier
2. Support mitosis and meiosis
3. Support spermiogenesis
4. Secrete inhibin (Inh)
5. Secrete androgen–binding protein (ABP)
6. Secrete Müllerian–inhibiting factor (MIF)

Question 22

Maintenance of Blood-Testis Barrier

Answer 22

• Blood–testis barrier:
• isolates seminiferous tubules
  from immune system
  (together with a complex interaction of physical
  & immunological factors)
  Sustentacular cells:
• joined by tight junctions
• divide seminiferous tubule into compartments

Question 23

Hormonal Regulation of Male Reproductive Function

Answer 23

GnRH in hypothalamus → anterior lobe of pituitary: secretes LH and FSH, LH → interstitial cells in testes→testosterone and FSH stimulate seminiferous tubules, both stimulate Sertoli cells/sustentacular cells→ABP and stimulation of spermatogenesis and spermiogenesis → inhibin and negative feedback

Question 24

Stimulated sustentacular cells promote

Answer 24

* division of spermatogonia * meiotic divisions of spermatocytes

Question 25

Androgen-Binding Protein (ABP)

Answer 25

* Binds androgens (primarily testosterone): in seminiferous tubule fluid * Is important in: * elevating androgen in seminiferous tubules * stimulating spermiogenesis * Production of ABP is stimulated by FSH (via sustentacular cells)

Question 26

Inhibin

Answer 26

Is a peptide hormone: * secreted by sustentacular cells in response to factors released by spermatozoa Depresses: * pituitary production of FSH * hypothalamic secretion of GnRH Gives sustentacular cells feedback control of spermatogenesis

Question 27

Müllerian-Inhibiting Factor (MIF)

Answer 27

* Is secreted by sustentacular cells in developing testes * Causes regression of fetal Müllerian ducts * In males, inadequate MIF production during fetal development leads to: * retention of ducts * failure of testes to descend into scrotum

Question 28

interstitial cells are stimulated by:

Answer 28

* Lutenizing hormone (LH) * Stimulated interstitial cells produce: * Testosterone * Stimulated interstitial cells : * promote male sexual characteristics * inhibit hypothalamus in releasing GnRH

Question 29

capacitation

Answer 29

Sperm capacitation is the final maturation step that sperm undergo inside the female reproductive tract to gain the ability to fertilize an egg. 1. Membrane Changes: Removal of cholesterol and glycoproteins from the sperm plasma membrane, making it more fluid and allowing better interaction with the egg. 2. Increased Motility: Sperm exhibit hyperactivation, characterized by stronger, more whip-like flagellar movements, helping them penetrate the egg’s protective layers. 3. Biochemical Changes: Increased levels of cAMP and activation of protein kinases alter sperm signaling pathways, preparing them for the acrosome reaction (the release of enzymes to penetrate the egg).

Question 30

3 Functions of the Epididymi

Answer 30

1. Monitors and adjusts fluid produced by seminiferous tubules 2. Recycles damaged spermatozoa 3. Stores and protects spermatozoa until use: * facilitates functional maturation by addition of specific proteins necessary for fertilization

Question 31

Spermatozoa become capable of fertilization

Answer 31

* when exposed to female reproductive tract * Destabilization of acrosome due to proteolytic and glycosidasic enzymes & removal of steroids by sterol binding proteins * Also become more motile! * Mammals only

Question 32

Roles of Ca²⁺ in Capacitation

Answer 32

The isthmus functions as a sperm store Non-identified chemotactic cues (egg) regulate the increase in [Ca2+]i * Attached sperm have low [Ca2+]i : maintains longevity and function * Detached sperms have high [Ca2+]i, enables more vigorous motility (flagellum)

Question 33

Loss of membrane cholesterol....

Answer 33

* Loss of membrane cholesterol is vital to fertilize an egg * During passage to the uterus, albumin and high-density lipoproteins act as cholesterol acceptors (=washed off) * Many glycosylphosphatidylinositol (GPI)-anchored proteins that are inhibitors of sperm-egg binding are lost from the membrane * Testis-specific isozyme of angiotensin converting enzyme (ACE) is only found in developing spermatids * ACE likely cleaves GPI-anchored proteins from sperm membrane

Question 34

4 Major Functions of Male Gland

Answer 34

Seminal vesicles, prostate gland, Cowper’s gland 1. Activating spermatozoa 2. Providing nutrients spermatozoa need for motility 3. Propelling spermatozoa and fluids along reproductive tract: * mainly by peristaltic contractions 4. Producing buffers: * to counteract acidity of urethral and vaginal environments

Question 35

Bulbourethral glands

Answer 35

Secrete alkaline mucus with lubricating properties Accessory glands producing seminal fluid

Question 36

At birth, male (precursor) germ cells

Answer 36

are present in sex cords of testis * sex cords become seminiferous tubules