OSSF II FINAL EXAM 2025/2026| EXPERT VERIFIED| COMPLETE QUESTIONS AND ANSWERS

Terms in this set (327) What are the three cells of the testes and their origins? 1. Sertoli (from coelomic epithelial cells of the gonald ridge) 2. Sperm (spematogonia from yolk sac) 3. Leydig cells (mesenchyme of genital ridge) Where is the tonic center and what does it do? Hypothalamus of the male Small frequent surges of GnRH induce production of LH, which stimulates production of testosterone Where is the surge center and what does it do? Hypothalamus of the female High amplitude surge of GnRh to produce LH, which is needed for ovulation What is male puberty? Age at which the majority of males in a given species/breed exhibit sufficient size and libido and produce adequate semen and sperm to produce pregnancies What is the hypothalamus inherently and what happens to it? Inherently female Testosterone defeminizes it How does testosterone affect the developing hypothalamus? 1. Produced by fetal tissues 2. Converted to estradiol by aromatase in brain 3. Eliminates surge center What does alpha-fetoprotein do? Binds estradiol, preventing it from crossing BBB in the CNS, which prevent females from defeminizing their own brains What is alpha-fetoprotein, where is it made, and what does it do? Glycoprotein made by yolk/fetal liver Carries FA's, regulates fetal blood osmolarity What are the factors leading to puberty? (3) 1. Metabolic (major) 2. Environmental/social cues 3. Genetics/breed How is puberty inhibited? 1. GnRH neurons in prepubertal male have increased sensitivity to negative feedback of T 2. Decreased sensitivity as puberty approaches What happens to the tonic center at puberty? Less sensitive to negative feedback of testosterone/estradiol What happens to GnRH at puberty? Frequency and amplitude increases -> increase LH secretion -> increased testosterone from Leydig cells What triggers pubertal change in hypothalamic sensitivity to T? 1. Neurons sense changes in BG and FA's 2. Receptors for leptin 3. Certain level of fatness required for puberty What do accessory sex glands and cells do to testosterone? What enzyme is required for this? In which sex does this occur? Convert testosterone to very potent DHT using 5alpha-reductase Happens in both males and females but females don't have a lot of testosterone to convert What are the accessory sex glands? (4) 1. Ampulla 2. Prostate 3. Vesicular gland (not in carnivores) 4. Bulbourethral gland (not in dog) What is T/DHT necessary for? Growth and maturation What happens if you remove testosterone? Accessory sex glands will regress What substances interfere with GnRH/LH? (3) 1. GnRH vaccine 2. LH receptor agonist (negative feedback via testosterone) 3. LH receptor antagonist (blocks receptor from LH) What happens at the initiation of spermatogenesis (2)? 1. Sertoli cells form blood barrier 2. Seminiferous tubules become hollow How long is the cycle of seminiferous epithelium? 60 days, so recent damage will not show up immediately How long will damage to the seminiferous tubules take to heal? 6-12 weeks What secretions from the sertoli cells control spermatogenesis (3)? 1. Inhibin - inhibits FSH 2. Estradiol - inhibits GnRH 3. AMH/MIS (fetal development), in adults may control meiosis What causes a lot of problems in the seminiferous tubules? There needs to be an extremely high concentration of testosterone What is the pattern of blood testosterone levels and why is this important? Episodic Prevents metabolic overload of clearance and sustained negative feedback on GnRH neurons and FSH What stimulates the sertoli cells? FSH What produces androgen-binding protein and what is its purpose? Sertoli Causes testosterone to become less lipophilic so that it's carried in fluid (seminiferous tubules) better What are the 3 components of immune privilege? 1. Anatomical (complex junctions) 2. Physiological (specialized transport systems) 3. Immunological (blood testis barrier) Why is it important to know that the testes are an immunologically privileged site? If sperm enter bloodstream, the body will produce antibodies against it (autoimmunity) What happens during spermiogenesis (5 steps)? 1. Acrosomal cap and granules form in golgi 2. Centioles form (implantation site for tail) 3. Elongation of nucleus 4. Migration of mitochondria to midpiece 5. Formation of flagella What are the components of the flagella (3)? 1. Capitulum (fits into depression in posterior nucleus) 2. Midpiece (mitochondria arranged in helix over axoneme 3. Tail (axoneme with microtubules) What are the nuclear changes in spermiogenesis? (3) 1. Elongated and chromatin condensed and keratinized via disulfide links 2. Transcription/translation stops and DNA cannot be accessed 3. Reversed after sperm enters oocyte