Male 1: Testicular compartment, Spermatogenesis Flashcards
Describe spermatogenesis
- Mitosis:
primary spermatogonia –> Secondary spermatogonia (diploid) - Seconadry spermatogonia increases in size –> Primary spermatocyte
- 1st mieotic division:
Primary spermatocyte —-> secondary spermatocyte (Haploid) - Second Mieotic division (actually mitosis):
Spermatocyte –> Spermatid (same haploid) - Spermiogenesis: Spermatid matures and acquires motility in the epididymis —> Spermatozoa
complete cycle of Spermatogenesis take about ___
64 days
Single primary spermatogonia gives rise to ____ spermatids/spermatozoa
512
Importance of Joined cytoplasmic bridges between developing germ cells arising from same 1ry spermatozoa
so that cells containing X chromosomes share essential products that dont exist in Cells containing Y chromosomes
otherwise, Y chromosomes containing cells would die
Progressive motility of spermatozoa depends on:
- Activation of CatSper ptn: Alkaline sensitive cation, which is more active at Cervical mucous pH=8 –> allows cAMP calcium influx
- Chemotaxis: they have olfactory receptors to odor like chemicals produced by ovary
Describe capacitation
exposure of sperm to female genital tract make it able to fertilize, by:
* Increasing its motility (catsper ptn & Chemotaxis)
* Preparation for acrosomal reaction
Importance of Capacitation
facilitatory more than obligatory, as fertilization could occur in vitro
Deficiency in spermatozoa ACE (Angiotensin converting enzyme) leads to:
Infertility
Enumerate importances of Sertoli cells
- Provide nutrinets (glycogen) & physical support to maturing germ cells
- Phagocytosis of debris from spermatogenesis
- Secretion of important substances for spermatogenesis
- Formation of blood-testis barrier
Substances secreted by Sertoli cells:
- MIS (mullerian inhibitory substance)
- Activin –> Stimulate FSH
- Inhibin —> Inhibits FSH
- ABP (Androgen Binding protein) —> maintain high androgens in tubular fluid by keeping constant concentration
- Aromataze –> Converts androgen to estrogen
- Estrogens
- Proteolytic enzymes
Function of proteolytic enzymes secreted by Sertoli cells
helps progression of developing germ cells towards the lumen
Explain how tubular fluid is different in composition from plasma
- Very little protein
- Very little glucose
- High androgens & estrogens
- Aspartic & glutamic acids
- Inositol
Explain how spermatozoa remain concentrated in Tubular fluid
via estrogen:
1. Estrongen binds to estrogen receptor Alpha
2. Increases reabsorption of water
Substances prevented to pass by Blood-testis barrier
- Antigeneic products from spermatogenesis to blood –> prevent autoimmune reaction
- Harmful blood agents into tubular lumen
Substances Allowed to pass by Blood-testis barrier
- Steroid
- Maturing germ cell (it has to break tight junctions created for blood-testis barrier in order to progress towards the lumen)
Function of LH in Spermatogenesis
Acts on Interstitial cells of Lyedig —> produce more Androgens (testosterone) to maintain spermatogenesis
Function of FSH in Spermatogenesis
- Sensitizes Leydig cells to LH by facilitating more LH receptors
- Promotes production of ABP (androgen binding protein)
- Acts on Sertoli cells in late stage spermatid maturation
Function of Activin & Inhibin
regulate FSH secretion
Androgens acting on sertoli cells is important for:
- Maintainace of germinal epithelium
- to complete miotic divisions
- early stage of Spermogenesis (spermatid –> spermatozoa) as it is Androgen dependent
Androgen levels are kept high locally for spermatogenesis by:
- Counter current exchange
- Androgen binding protein (ABP)
- High number of Leydig cells
other hormones important for Spermatogenesis
- Growth hormone (for early)
- prolactin (for early)
- Thyroixine
- Leptin (for start)
- Estrogen (mediate actions of FSH)
Explain how optimum temperature of 35 for spermatogenesis is aquired:
- Absence of subcutaneous fat in scrotum
- if weather is cold, dartos muscle contrats to proximate testis towards body
- Scortum is located outside abdominal cavity
Factors inhibiting Spermatogenesis
- X ray/irradiation (irreversible but leydig cells still secrete tetosterone)
- bacteria
- Chemical toxins
- Prolonged fever
- hot baths more than 40 degrees for more than 30 mins
- Tight pants
Balanced diet vital for Spermatogenesis should contain:
- Zinc
- Selenium
- Vit A,B,C,E
