Spermatogenesis Lecture Notes PDF

SPERMATOGENESIS DR.R.A. AKINDELE  SPERM STRUCTURE Sperm cells are amongst the smallest in the body (~1/20 mm). Simple construction: head and tail. Tail is a flagellum – whipping motion provides motility. Base of tail contains a coiled mitochondrion to provide power for...

SPERMATOGENESIS DR.R.A. AKINDELE  SPERM STRUCTURE Sperm cells are amongst the smallest in the body (~1/20 mm). Simple construction: head and tail. Tail is a flagellum – whipping motion provides motility. Base of tail contains a coiled mitochondrion to provide power for movement. Head contains nucleus and an organelle called an ACROSOME. Acrosome contains digestive enzymes that helps sperm to PROCESS OF TRANSFORMATION OF THE MALE GERM CELL SPERMATOGOONIA TO SPERMATOZOA  Cellular proliferation by mitosis to form primary spermatocytes  Two reduction division by meiosis to produce haploid spermatids  Cell differentiation by a process called spermiogenesis when spermatids differentiate into spermatozoa PRIMORDIAL CELLS mitosis SPERMATOGONIUM mitosis 1 SPERMATOCYTES meiosis 2 SPERMATOCYTES meiosis SPERMATIDS spermiogenesis MATURE SPERMATOZOA  It starts at puberty due to rising gonadotropin and testosterone level  It occurs in the seminiferous tubule  Time from spermatogonium to a spermatozoa is 65- 70 days  New cycles are initiated every 2-3 weeks  In adult human testis between 30-200 million spermatozoa are produced per day  It is maintained till old age BLOOD TESTIS BARRIER  Tight junctions in the wall of the seminiferous tubules  It protects the site of spermatogenesis  It prevent proteins from moving into the lumen of the seminiferous tubule  It prevents spermatozoa from moving into the circulation  Spermatozoa is highly antigenic WHAT FACTORS REGULATE SPERMATOGENESIS  GnRH  FSH  LH  Inhibin(negative feedback)  Testosterone(paracrine)  Oestrogen  Growth hormone  ROLES OF THE FACTORS  Proliferation GH, Testosterone  Growth GH, Testosterone  Maturation Testosterone  Transformation Testosterone, oestrogen, FSH ROLES OF SERTOLI CELL IN SPERMATOGENESIS  Has receptors for FSH and testosterone  Form the blood testes barrier  Nourish developing sperm  Produce androgen binding protein  Produce oestrogen which act as a paracrine agent to stimulate differentiation  Produce inhibin which inhibit FSH secretion from anterior pituitary  Phagocytose defective sperm OTHER ROLES OF SERTOLI CELLS  Secrete Mullerian Inhibitory factor during embryonic life  Sertoli cell are non proliferating cells if they are destroyed by infection or injury spermatogenesis will stop.  ROLE OF LEYDIG CELLS  Steroidogenesis – Secrete testosterone  Lack FSH receptors  Has LH receptors  Has oestrogen receptors  Sertolis cell stimulate its growth through oestrogen  EXTERNAL AGENTS THAT CAN AFFECT SPERMATOGENESIS  Sperm cells are rapidly dividing and undergoing meiosis external agents can alter division a. Chemical carcinogen b. Chemotherapeutic agents c. Drugs d. Environmental toxins e. Irradiation f. Extreme temperature  EXTERNAL FACTORS CONTD Smoking Malnutrition and Nutritional Deficiencies Obesity Bicycling Varicocele  GENETIC FACTORS AFFECTING SPERMATOGENESIS 1. KLINEFELTER XXY: they have seminiferous tubule dysgenesis 2. Kartagener Syndrome: we have reversal of position of major organs immobile cell is affecting sperm tails 3. Cystic fibrosis: associated with missing or obstructed vas deferens  HORMONAL REGULATION IN MALES GONADOTROPIN RELEASING HORMONE (GnRH) – stimulates secretion of Follicle Stimulating Hormone and Luetinizing Hormone. This happens when there is a low concentration of testosterone. FOLLICLE STIMULATING HORMONE (FSH) and LEUTINIZING HORMONE (LH) – both produced by anterior pituitary. Responsible for stimulating spermatogenesis and testosterone secretion. TESTOSERONE – stimulates development of male sex organs, as well as secondary sexual characteristics. Participates in feedback loop involving GnRH. Also inhibits secretion of LH.  Male Reproductive Physiology Testes Spermatogenesis Hormonal Control Flow Chart SEMINAL FLUID ANALYSIS  Also known as a sperm count and male fertility test  Itis use to evaluate the fertility status in a man by analyzing and measuring the quality and quantity of his semen ADVICE BEFORE SEMINAL FLUID ANALYSIS  Abstain from intercourse for 3 days  Avoid alcohol consumption and smoking  Avoid substance abuse: marijuana and cocaine  Sample should be produced at the lab or kept close to the body temperature to the lab  Analysis is usually done within 30minutes to one hour after collection COMPUTER ASSISTED SEMEN ANALYSIS  Automatic or semi automatic semen analysis  Based on image analysis  Tracking cell movement on a digitizing tablet  Can assess sperm concentration  Canassess motility characteristics such as velocity  Analysis can be done in few seconds  There are many types of CASA systems TYPES OF CASA  Sperm Quality Analyzer or Sperm lite (sqav)  Integrated Semen Analyzer(ISAS)  Sperm Class Analyzer (SCA)  Integrated Visual Optical System(iVOS sperm Analyzer) DRAW BACK OF CASA SYSTEM  The computer is only as intelligent as its programmer  Small change in the computer program can alter the results significantly  The computer must constantly be monitored and updated  Any abnormal result must be verified by a manual chamber method SPERM PENETRATION ASSAY (SPA) (HAMSTER TEST)  Eggs and ova of hamsters with the outermost layer removed  Eggs are exposed to prepared sperm from the man being tested  If sperm cell penetrate the hamster egg it will most likely be able to fertilize a human egg  High false negative result(not able penetrate hamster but wife gets pregnant)  Failed hamster test: man may benefit from ICSI- intracytoplasmic sperm injection. METHODS OF COLLECTION  Usea clean specimen bottle with a wide opening 1 masturbation 2. Coitus interruptus 3. Collection condom 4. Regular condom after cleaning lubricant and spermicides METHODS OF ANALYSIS  Makler counting chamber  Computer assisted Semen Analysis (CASA)  Hem cytometer MAKLER COUNTING CHAMBER  Place a small uncalibrated drop from a well mixed undiluted specimen in the center of the chamber  Cover with a slip  Use a microscopic objective of 20x  MOTILITY  Pick about 10 squares  Count the number of motile sperms and grade  Count the number of non motile sperm  Calculate the percentage of motility SPERM COUNT  Transfer a part of the original specimen to another test tube for immobilization by insertion of the tube into hot water  Place a drop of the specimen into the chamber  Count sperm heads in 10 squares  The numbers represent conc in million per ml POST COITAL TEST  Also known as Huhner test or sim humer test  It evaluates the woman’ s cervical mucus at time of ovulation  Evaluates mucus interaction with the husband sperm NORMAL SEMINAL FLUID ANALYSIS ANALYSE NORMAL 1. Volume 2-6mls 2. Liquefaction time 20-30mins after collection (long 3.Sperm count >20million/ml 4.Sperm morphology > 30% normal head form 5. Sperm motility > 50% forward progressive motility 6.Antibody 6ml 2. Hyposepermia: semen volume < 1.5mls 3. Aspermia: no semen volume 4. Oligospermia: 40% 7. Necrospermia : Non- viable sperm 8. Oligoastheteratospermia: 4,5,6 together