details for formation of sperma nd other realted things

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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