Spermatogenesis is the process by which sperm cells are produced in the testes. It involves three main phases: spermatocytogenesis, meiosis, and spermiogenesis. Spermatocytogenesis involves the division of spermatogonia stem cells into spermatocytes. Meiosis reduces the chromosome number from diploid to haploid. Spermiogenesis transforms round spermatids into elongated spermatozoa through morphological changes. The entire process takes approximately 74 days and occurs in the seminiferous tubules of the testes, producing 200-300 million sperm cells daily.

1. SPERMATOGENESIS

2. WHAT IS SPERMATOGENESIS?
• Spermatogenesis - Spermatogenesis is the process by which haploid spermatozoa
develop from germ cells in the seminiferous tubules of the testis.
• Spermatozoa (Sperm cell)- These are mature male gametes.
• Spermatogenesis is the male version of gametogenesis, of which female equivalent is
oogenesis.
Reference: Wikipedia https://en.wikipedia.org/wiki/Spermatogenesis

3. • Spermatogenesis is highly dependent optimal conditions for the process to occur correctly. Ex : temperature 1°- 8°C lower than normal body temperature of 37°C.
• Starts at puberty and usually continues uninterrupted until death, although slight decrease can be discerned in the quantity of produced sperm with increase in age.
• Importance of sperm – sperm is the counterpart to female gametes, the oocyte , during conception to produce zygote.
• Duration - The entire process approximately 74 days (according to tritium labelled biopsies) and approximately 120 days (according to DNA clock measurements).
• Testis produce around 200 to 300 million spermatozoa daily. However, only half or 100 million of these become viable.
Reference : Wikipedia https://en.wikipedia.org/wiki/Spermatogenesis

4. WHY IS SPERMATOGENESIS
IMPORTANT? WHERE DOES IT OCCUR?
THE THREE PHASES:
• To produce mature male gamete
• To preserve number of chromosomes in
offspring
I. Spermatocytogenesis
II. Meiosis
III. Spermiogenesis
Reference : Wikipedia. https://en.wikipedia.org/wiki/Spermatogenesis

5. Reference : https://dev.biologists.org/content/135/13/2207.figures-only

6. • It is the male form of gametocytogenesis and involve stem cells dividing to replace themselves.
• Gametocytogenesis: creation of gametocytes by mitotic division of gametogonia.
• The stem cells involved are called spermatogonia.
PHASE I: SPERMATOCYTOGENESIS
Three functionally separate spermatogonial cell types are recognized on basis of appearance of the nuclei:
1. Type Ad (dark)
2. Type Ap spermatogonia (pale)
3. Type B spermatogonia
Reference : Smith, D.J. (2009). "Human sperm accumulation near surfaces: a simulation study" (PDF). Journal of Fluid Mechanics. 621: 295. Bibcode:2009JFM...621..289S. doi:10.1017/S0022112008004
Yves (March 1966). "Renewal of spermatogonia in man". American Journal of Anatomy. 118 (2): 509–524. doi:10.1002/aja.100118953. Retrieved 20 May 2012.

7. Reference: Wikipedia https://en.wikipedia.org/wiki/Spermatogonium

8. The entire process of spermatocytogenesis by which spermatogonial stem cells divide and
differentiate into spermatozoa includes four stages, those four stages are as follows:
• STAGE I, SPERMATOGONIUM: an undifferentiated male germ cell originating in the seminal tubule
and dividing into two spermatocytes.
There are three types of spermatogonia in humans, they are;
1. Type Ad (dark)
2. Type Ap spermatogonia (pale)
3. Type B spermatogonia
References: Simorangkir, D.; Wreford, N. (1998-04-01). "Spermatogenesis". Human Reproduction. 13 (suppl_1): 1–8. doi:10.1093/humrep/13.suppl_1.1. ISSN 0268-1161.

9. • STAGE II, SPERMATOCYTE: the mother cell of spermatid. > Primary spermatocyte. > Secondary spermatocyte.
• STAGE III, SPERMATID: a cell produced by meiotic division of a secondary spermatocyte. It develops into the spermatozoa.
• STAGE IV, SPERMATOZOAN: A mature male germ cell, the specific output of the testes which fertilize the mature ovum in sexual reproduction.
Reference : Laura Giojalas.Sperm guidance in mammals Nature Reviews: molecular cell biology. May, 2006

10. • The primitive sex cell appear earliest in 4th week of intra uterine life in the wall of yolk sac as primordial germ cell.
• At puberty the germ cell awaken and start the actual process of spermatogenesis.
• Spermatogonia are germ line cells. They are diploid (2n).
• One of these spermatogonia undergoes meiosis and is called primary spermatocyte.
• The primary spermatocyte undergoes meiosis I to produce secondary spermatocyte.
Reference : Yves (March 1966). "Renewal of spermatogonia in man". American Journal of Anatomy. 118 (2): 509–524. doi:10.1002/aja.100118953. Retrieved 20 May 2012.

11. PHASE II : MEIOSIS
• This is the creation of spermatids from secondary spermatocytes.
• Secondary spermatocytes produces earlier rapidly enter meiosis II and divide to
produce haploid spermatids.
• The brevity of this stage means that secondary spermatocytes are rarely seen in
histological studies.
• Occurs after puberty
Reference : Wikipedia https://en.wikipedia.org/wiki/Spermatogenesis#Spermatidogenesis

12. • Primary spermatocytes remain in the prophase of 1st meiotic division for 16 days.
• Each contains 22 pairs of autosomes and one pair of sex chromosome XY.
• Each secondary spermatocyte has equal chromosomes (22+X) or (22=Y).
• Each of these divides again thus forming four spermatids.
Reference : http://www.uwyo.edu/wjm/repro/spermat.htm

13. PHASE III : SPERMIOGENESIS
• Spermiogenesis is responsible for the formation of mature cells that
are not yet motile.
• It has four phases:
I. Golgi phase
II. Cap phase
III. Tail phase
IV. Maturation phase
Reference : https://www.biology-online.org/dictionary/Spermiogenesis

14. I. GOLGI PHASE
• Where the set of events begins.
• It’s called the golgi phase because of the intendified
activity of the golgi apparatus.
• The genetic material is tightly packed, highly.
condensed transcriptionally inactive.
Reference : https://www.biology-online.org/dictionary/Spermiogenesis

15. II. CAP PHASE
• Characterized by events leading to the formation of
the acrosomal cap.
• The acrosomal cap is a membrane bound
compartment.
• The acrosome-acroplaxome-manchette complex.
Reference : https://www.biology-online.org/dictionary/Spermiogenesis

16. III. ACROSOMAL PHASE
• The spermatid nucleus begins to elongate and the acrosome
eventually covers the majority of the anterior nucleus.
• The manchette forms in the region of the caudal half of the
nucleus and extends down toward the developing flagellum.
• The neck and the annulus are formed and will later become the
juncture between the middle piece and the principal piece.
• All the components of the developing spermatid are completely
surrounded by a plasma membrane.
Reference : https://www.biology-online.org/dictionary/Spermiogenesis

17. IV. MATURATION PHASE
• Mitochondria forms a spiral assembly around the
flagellum that defines the middle piece.
• The postnuclear cap is formed from the manchette
microtubules.
• The annulus forms the juncture between the middle
piece and the principal piece.
Reference : https://www.biology-online.org/dictionary/Spermiogenesis
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18. PARTS & FUNCTIONS OF SPERM
Reference : https://www.pinterest.ph/pin/178807047678002950/?lp=true

19. HORMONES INVOLVED:
Reference: https://en.m.wikipedia.org/wiki/Spermatogenesis
https://courses.lumenlearning.com/suny-ap2/chapter/the-pituitary-gland-and-hypothalamus/

20. Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3271653/

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