1. Describing spermatogenesis
16 April 2017
WALT
Describing spermatogenesis
WILF:
Identify the internal structures of the testis
Describe the stages of development of the sperm cells
Relate this to the internal structure of the testis
Associated knowledge:
Mitosis
Meiosis

2. A Testis

3. A section across a testis
Many seminiferous tubules are shown. These make the spermatozoa

4. One seminiferous tubule
Sertoli (nurse) cells supply nutrition and protect the maturing sperm.

5. Interstitial cells
(Leydig cells) produce testosterone
2. Spermatogonia
3. Spermatocytes
4. Spermatids
5. Spermatozoans
(sperm cells)

6. Spermatogenesis

8. Secondary spermatocyte
Label the diagram to show the stages of spermatogenesis then describe the sequence of events
Primary spermatocyte
spermatids
Spermatozoa
spermatogonium
Germinal epithelium
Secondary spermatocyte
Sertoli cells

9. Notes from the student guide on spermatogenesis
The production of gametes in the gonads is known as gametogenesis.
• Spermatogenesis is the formation of sperm in the testis.
The cells of the germinal epithelium of the testis undergo a sequence of mitotic and
meiotic divisions to form haploid gametes. It is important that the gametes are haploid so that at fertilisation the diploid number is restored.
First there is a multiplication stage which involves repeated mitotic divisions to produce spermatogonia
Once formed they grow to full size and then undergo maturation which involves meiotic division, and then differentiation into the mature gametes.
Spermatogenesis is the process by which spermatozoa are produced. This takes place in the germinal epithelium of the seminiferous tubule.
The diploid spermatogonia divide many times by mitosis to produce primary spermatocytes.
These then undergo meiosis and after the first meiotic division form haploid secondary spermatocytes.
After the second meiotic division they form spermatids which differentiate into mature spermatozoa.
In the wall of the seminiferous tubule are the Sertoli cells. They secrete a fluid which nourishes the spermatids and protects them from the immune system of the male.
There are also groups of interstitial cells which secrete the male sex hormone.

10. • Oogenesis is the formation of eggs or ova in the ovary.
The cells of the germinal epithelium of the ovary undergo a sequence of mitotic and
meiotic divisions to form haploid gametes. It is important that the gametes are haploid so that at fertilisation the diploid number is restored.
First there is a multiplication stage which involves repeated mitotic divisions to produce oogonia. Once formed they grow to full size and then undergo maturation which involves meiotic division, and then differentiation into the mature gametes.
Oogenesis is the process by which ova are produced in the ovary.
􀀹 Oogonia, which are formed before birth, undergo mitosis to form primary oocytes.
􀀹 The primary oocytes start to divide by meiosis but the process stops at prophase I.
􀀹 The germinal epithelium also divides to form follicle cells which surround the primary oocytes to
form primary follicles.
􀀹 (The primary oocytes do not mature until just before ovulation. About two million of these are
formed in the ovary of the foetus but only about 450 will later develop into secondary oocytes
after the onset of puberty.)
􀀹 At puberty hormones stimulate the follicles to develop further. Each month several follicles start
to develop but only one matures into a fully developed Graafian follicle.
􀀹 􀀃􀀃First􀀃􀁗he primary oocyte completes the first meiotic division to form the haploid secondary
oocyte and a small polar body.
􀀹 The mature Graafian follicle migrates to the surface of the ovary where it bursts and the
secondary oocyte is released, a process called ovulation.
􀀹 The secondary oocyte begins the secondary meiotic division but this is arrested as metaphase
unless fertilisation takes place. On fertilisation this division is completed to form a large ovum
and a second polar body. Once this division has taken place the nucleus of the ovum fuses with
that of the sperm to form a zygote which will then develop into an embryo.