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Course
BIOL 235

Institution
Athabasca University (AU )

Lecture notes study book Principles of Anatomy and Physiology of Gerard J. Tortora, Brendan Burkett, Bryan H. Derrickson, Julie Cooke, Danielle Dye, Tara Diversi, Mark McKean, Rebecca Mellifont, Latika Samalia, Greg - ISBN: 9780730314622 (Notes)

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Uploaded on November 26, 2021
Number of pages 11
Written in 2021/2022
Type Class notes
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biol235

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1

Chapter 28: The Reproductive System

Male Reproductive System:
 testes, a system of ducts (epididymis, ductus deferens, ejaculatory ducts and urethra), accessory
sex glands (seminal vesicles, prostate, bulbourethral glands) and supporting structures (scrotum
and penis)
o testes: male gonads; produce sperm and secrete hormones
o ducts: transport and stores sperm; assist in maturation and convey to exterior
o semen: sperm and the secretions provided by accessory glands
o penis: delivers sperm into female tract
o scrotum: supports testes
 Scrotum:
o supporting structure for testes
o looks like a single pouch of skin separated into lateral portions by raphe and separates
into 2 sacs of one testis
o septum: subcutaneous layer and muscle tissue= dartos muscle
o location and contraction of its muscle fibers regulate the temperature of testes
o normal sperm production: temp about 2-3 degrees below core body temp
 Testes:
o testicles; paired oval glands in the scrotum
o testis (singular); has a mass of 10-15g
o develop near the kidneys in the posterior portion of abdomen
o tunica vaginalis: serous membrane; forms during the descent of testes and partially
covers it
 hydrocele: collection of serous fluid- may be caused by injury to testes or
inflammation of epididymis
o tunica albuginea: internal; white fibrous capsule- forming septa that divides the testis
into lobules
 seminiferous tubules: where sperm is produced= spermatogenesis
 spermatogenic cells: sperm-forming
 sustentacular cells: supports spermatogenesis
o nourish spermatocytes, spermatids and sperm; phagocytize
excess spermatid cytoplasm and develop proceeds and controls
movements of spermatogenic cells and release sperm into the
lumen of seminiferous tubule
o spermatogonia: tight junctions join neighbouring sustentacular
cells to one another and form an obstruction called blood-testis
barrier (substances they must pass through here fore they
reach developing sperm)
o this barrier prevents an immune response against
spermatogenic cell’s surface antigens (foreign) by the immune
system
 sperm cell: once formed; released into the lumen of this tubule
 interstitial cells: between adjacent seminiferous tubules; clusters of
cells that secrete testosterone and androgen: hormone that promotes
the develop of masculine characteristics

, 2

 spermatogenesis:
 takes 65-75 days and begins with spermatogonia that contain the
diploid (2n) number of chromosomes
o spermatogonia are types of stem cells and when they undergo
mitosis, some spermatogonia remain near the basement
membrane of the seminiferous tubule for future cell division
and sperm production
o primary spermatocytes: are diploid (2n) that has 46
chromosomes and once formed – each one replicates its DNA
and then meiosis begins
 meiosis I: homologous pairs of chromosomes line up at
the metaphase and cross over occurs meiotic spindle
pulls one (duplicated) chromosome of each pair to an
opposite pole of the dividing cell
 2 cells formed: secondary spermatocytes:
o each has 23 chromosomes, the haploid
number (n)
o no DNA replication occurs here
 meiosis II: chromosomes line up in a single file along
the metaphase plate, 2 chromatids of each
chromosome separate
 the resulting 4 haploid cells are called
spermatids
 as spermatogenic cells proliferate—they fail to complete cytoplasmic
separation—cells remain in contact via cytoplasmic bridges
 spermiogensis: final stage
o development of haploid spermatids into sperm, no cell division
o each spermatid becomes a single sperm cell
o acrosome forms atop nucleus that condenses and elongates, a
flagellum develops and mitochondria multiply
o sperm are released from their connections to sustentacular
cells –an event known as spermiation (sperm enter the lumen
of seminiferous tubule—fluid secreted by sustentacular cells
pushes sperm towards the ducts of testes (cannot swim)
 Sperm:
 head and tail
 nucleus: 23 chromosomes
 acrosome: cap like vesicle filled with enzymes that help a sperm to
penetrate a secondary oocyte to bring about fertilization
(hyaluronidase and proteases)
 tail: 4 parts: neck, middle piece, principal piece and end piece
o neck: constricted region that contain centrioles- form the
microtubules that comprise the remainder of the tail
o middle piece: contain mitochondria in a spiral that provide
energy (ATP) for locomotion of sperm to the site of fertilization
and for sperm metabolism

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