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By the end of this section, you will be able to:
  • Describe human male reproductive anatomy (structures and functions)
  • Describe spermatogenesis a
  • Describe the role of hormones in human reproduction
  • Describe the roles of male reproductive hormones

Human reproductive anatomy

The reproductive tissues of male and female humans develop similarly in utero until about the seventh week of gestation when a low level of the hormone testosterone is released from the gonads of the developing male. Testosterone causes the primitive gonads to differentiate into male sexual organs. When testosterone is absent, the primitive gonads develop into ovaries. Tissues that produce a penis in males produce a clitoris in females. The tissue that will become the scrotum in a male becomes the labia in a female. Thus the male and female anatomies arise from a divergence in the development of what were once common embryonic structures.

Male reproductive anatomy

Proper development of sperm cells requires a temperature slightly lower than the normal body temperature; therefore, the pair of testes must be suspended outside the pelvic cavity (in the scrotum) so the environment of the sperm is about 2 °C lower than body temperature. If the testes do not descend through the abdominal cavity during fetal development, the individual has reduced fertility.

The scrotum    houses the testicles or testes    (singular: testis), and provides passage for blood vessels, nerves, and muscles related to testicular function. The testes are a pair of male gonads that produce sperm and reproductive hormones. Coiled in each testis are seminiferous tubules, where sperm production begins.

The penis    drains urine from the urinary bladder and is a copulatory organ during intercourse ( [link] ; [link] ). The penis contains three tubes of erectile tissue that become engorged with blood, making the penis erect, in preparation for intercourse. The organ is inserted into the vagina culminating with an ejaculation. During orgasm, the accessory organs and glands connected to the testes contract and empty the semen (containing sperm) into the urethra and the fluid is expelled from the body by muscular contractions causing ejaculation. After intercourse, the blood drains from the erectile tissue and the penis becomes flaccid.

Semen is a mixture of sperm (about five percent of the total) and fluids from accessory glands (prostate, bulbourethral glands, and seminal vesicles) that contribute most of the semen’s volume. Sperm are haploid cells, consisting of a flagellum for movement, a neck that contains the cell’s energy-producing mitochondria, and a head that contains the genetic material ( [link] ). An acrosome (acrosomal vesicle) is found at the top of the head of the sperm. This structure contains enzymes that can digest the protective coverings that surround the egg and allow the sperm to fuse with the egg. An ejaculate will contain from two to five milliliters of fluid and from 50–120 million sperm per milliliter.

Micrograph shows human sperm, which have an oval head about 3 microns across and a very long flagellum.
As seen in this scanning electron micrograph, human sperm has a flagellum, neck, and head. (credit: scale-bar data from Matt Russell)

Questions & Answers

what is the specialize functions of the organs
Donieta Reply
what organs?
Maureen
what is the faction of photo receptors in the eye
Mutangana Reply
transduction of light to nervous impulses occurr it is located in the retina
Maureen
wat are e constituents of blood
marybertiny Reply
Can a cell be destroyed by the bacteria
Makhanya Reply
anamia. because of loss of blood
fon Reply
Name the element which is liquid
Sandeep Reply
hg
RC
CO2
Maureen
Bromine
Aaron
what is the dept of respiration plz?
Maureen
Maureen where are you from
Omokaro
mercury
VANESSA
bromine
VANESSA
which of the muscle can work with out getting tired?
nikkita
heart
Anam
Hg
Samiullah
what is the unit of muscles?
Samiullah
acid are organic or inorganic
Samiullah
why is the baby formed in the uterus n not else where?
Ekali Reply
you may help me ,to know why
mar
lo i am inn
mar
the womb is to protect the baby because inside the womb the lay in a fluid called the amniotic fluid which keeps the baby warm and it also have the placenta which the baby feeds from
Maureen
atom, molecules, organelle, cell, tissue, organ, organ system
Cheila Reply
sub atom atom molecular molecules and cells.
Advertus
cells structural level.
Advertus
what is microorganisms I am a laboratory student.
Advertus
a small organism
Rahbliss
small organism that can only be seen under a microscope
Maureen
i am just interested to be part of ,to learn
mar
explain why is it that old peoples as from the age of 60 usually have eye problems?
Kenn Reply
most old people suffere eye problems.because of short sight where individuals with this kind of problems see only near objects clearly but not distance objects, this is cause by elongated eyeball so light from distance is focus infront the retina so the image on the retina is blurred .
Munyah
plasma DNA cytoplasm Ribosome
Pearl Reply
cell, tissue,organ, organ systems,organism
Pearl Reply
cell is the build block of Life
Pearl
also a smallest unit of life
Frankline
sure..
Pearl
consistsof cytoplsm enclosed with in a membrane which contains many biomolecules such as proteins and nucleic acids
Frankline
differences in the effects of infection by HIV and influenza A virus on host genetic variability.
Yo Reply
i dont know
Ubah
hiv is direct contact of blood or body fluid and if not treated can break down the immune system faster and lead to acids with complications of pneumonia skin infections inflammation of the brain etc.while influenza A is a air borne virus which can cause the common cold pain fever and can be cured
Maureen
A.I.D.S
Maureen
suggest bioingormatics research article plz
peermehirali
what makes the heart to pumps blood?
Jamer Reply
sa node
Ubah
i do think its the nerve tranmission to the brain
Frankline
The contracting and relaxing of the atria and vertricles but the electrical system of the heart is what makes this possible.
keynia
yes which is called autorhymicity
Maureen
Yes,,by sucking blood leading to the weakening of cells,and finally it will be destroyed....
R0se
adrenoline action in brains
Frankline Reply
please describe the human heart brefly
Shah Reply
the size of the heart is like a fist. it has four chambers. the left and right upper atrium which push blood in the lower left and right ventricles which in turns pump blood to the lungs or the rest of the body.
Maureen
how do u prove it
Frankline
Maureen is correct ,
Davis
right
Kenn
right
Ubah
hi
horyaal
mxaa lahayaa
horyaal

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Source:  OpenStax, Human biology. OpenStax CNX. Dec 01, 2015 Download for free at http://legacy.cnx.org/content/col11903/1.3
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