Lecture 21 - Reproductive Histology PDF

REPRODUCTIVE HISTOLOGY Thomas Wilson Graphics from Grant’s Method of Anatomy, Netters Atlas of Human Embryology, Larsen’s Anatomy, Human Embryology and Developmental Biology, Moore’s Before We Are Born, Analysis of Vertebrate Structure, McMinn’s & Abrahams Clinical Atlas of Anatomy, Human Ana...

REPRODUCTIVE HISTOLOGY Thomas Wilson Graphics from Grant’s Method of Anatomy, Netters Atlas of Human Embryology, Larsen’s Anatomy, Human Embryology and Developmental Biology, Moore’s Before We Are Born, Analysis of Vertebrate Structure, McMinn’s & Abrahams Clinical Atlas of Anatomy, Human Anatomy Colour Atlas & Textbook, Textbook of Histology, Stevens & Lowe’s Human Histology [email protected] Goal: To recognise the difference in functional roles and complexity between the reproductive tracts Outline: Outcomes: Relate structure to function. Histology of the female reproductive tract Identify and describe the main histological features of the female and male reproductive tracts, relating each section to embryological development. Histology of the male reproductive tracts Differentiate between the various types of ovarian follicles, and histological appearance of the endometrium at different menstrual stages. t  Ovary Hilum, medulla, and cortex Cortex: Follicles, corpus luteum/albicans Medulla: mostly blood vessels Also has tunica albuginea hilum ÷:: Ovary Follicles house and nurture developing oocytes too 1. Primordial follicle: Formed during fetal life Primary oocyte (PO) + Produces oestradiol and inhibin 2. Pre-antral (primary) follicle: Smaller number form during puberty PO + ↓M} ?? layers of granulosa cells (cuboidal) Thecal (stromal) cells surround the whole follicle squamous like - Zona pellucida: glycoprotein layer secreted by oocyte , - ←EÑEN µ☒ → fluid component inside the follicle - ubundantoestradoil 3. Antral (secondary) follicle: Antrum made under gonadotropin stimulation ✓ thicker layer & thicker layer of theca cells Granulosa cells secrete fluid  antrum More product produced as Antrum Ovary Cumulus ' Oophorus Dominant (mature/preovulatory/tertiary/Graafian) follicle: 7-25mm (!!) Only 1 forms per cycle (reproductive fitness) Others undergo atresia rthemassiv Corona Antral expansion and large increase in oestradiol secretion radiata Cumulus oophorus: thickened layer of granulosa cells Corona radiata: Granulosa cells surrounding the oocyte Follicle ruptures  transient endocrine organ: corpus luteum Granulosa cells of follicle  GC of corpus luteum  enlarge Produce progesterone, oestradiol and inhibin A Active in pregnancy for ~3month Dominant follicle If no pregnancy  Corpus albicans (scar tissue) after ~10-12days Corpus albicans Corpus luteum  Uterine tube µ opening rtwidening ronnarrowing 3 sections: Infundibulum  Ampulla  Isthmus Ampulla Isthmus Fimbriae move closer to ovary at ovulation mucosa / folds Mucosal folds ↑ in complexity towards infundibulum Mechanism of slowing sperm down (~5 days) 1. Prolong availability, avoids polyspermy Site of fertilisation: Ampulla Transport and nurture oocyte to uterus motility Epithelium: Ciliated cells and secretory (peg) cells Both are columnar cells Composition changes from infundibulum to isthmus { Ampulla : secretory & motility cells § Isthmus : more secretory & less motility cells Muscularis externa: inner circular, outer longitudinal layers  ±÷aiEi FUNCTIONAL LAYER Uterus [ ^ É Endometrium £ ¥ Basal layer: Retained throughout cycle, regenerative layer Function layer: Sloughed during menstrual cycle in all upper primates Driven by changes in ovarian steroids: Oestradiol and progesterone 3 phases § E Myometrium: Thick smooth muscle layer É 0 É Undergoes hypertrophy during pregnancy Rhythmic contractions 2. Secretory (progesterone) 3. Menstruation 1. Proliferative (oestradiol) nourishes early foetus → by diffusion Uterine milk produced by uterine gland * ↳ cellular components between uterine glands are starting to degrade very small uterine glands ] ↳ Cervix and Vagina Cervix functions Holds the baby in: Thick with smooth muscle Regulate the transport of sperm through endocervical canal Lined by simple columnar epi Invaginate to form cervical glands ectocervixrooutsideofe.no/ocervicaIcanaI Secretion consistency is hormone dependent Oestrogen: Fertile, watery mucous Progesterone: Infertile, thick/sticky mucous Ectocervix: Vaginal surface Vagina A ' 6 roofoifiel § § Stratified squamous epithelium, high in glycogen (oestrogen) Broken down to lactic acid by bacteria = ↓pH → to make environment É E more hostile is Rugae folds in the mucosa: allows distention TRANSITIONAL ZONE § Intercourse and child birth % ± Muscularis externa of smooth muscle Voluntary muscle of bulbospongiosus at vaginal orifice ¥É , Testes and ducts µ continuation of peritoneal cavity Testis surrounded by tunica vaginalis: mobility Lined by mesothelial cells ↳ lubrication 1. Seminiferous tubules – sperm production 250-350 lobules per testis µ encroaches into the testicle as part of little septa Lobules made by Tunica Albuginea (thick collagen fibres) Convoluted and straight components :* ↳ feed into rete testis 2. Rete (means ‘net’) testis – funnelling network Tissue as a whole, described as mediastinum 3. Efferent ductules – fluid reabsorption From what were the mesonephric tubules f-& ED feeds into epi at cranial pole of testes \ 4. Epididymis – sperm maturation, transport Start of the MAIN mesonephric duct contribution 5. Vas deferens – sperm transport, storage Seminiferous tubules YOUNGER {% ; " a Tubules wrapped in tunica propria Basal lamina, smooth muscle, collagen tissue Only true tubular structures from puberty Site of gametogenesis Sertoli cells = ‘ghostly’ appearance (~10% of cell count in adult) They are support cells that remove wastes Higher proportion in pre-pubescent males Peripheral germ cells Ad/Z/P : spermatogonia / primary spermatocytes Not motile Sz : spermatozoa = motile (have tail) Interstitial space, between tubules Leydig cells: Androgen secretion interstitial space of To maintain of secondary sexual characteristics ① * ⇐ "  Efferent ductules Rete testis  efferent ductules Transport sperm and reabsorb fluid secreted by I Sertoli cells ~20 efferent ductules Superior pole of testis i I Pseudostratified columnar cells % Tall = ciliated (cilia need space in cell) Short = absorptive, no cilia } makes stellate lumen - shaped Circular SM organisation increases LB nuclei are more oval , stretched & paler ④~tT#sm F€☒Fibroblast Converge to form singular epididymis Epididymis spermatozoa Pseudostratified epithelium Principal cells (PC): Tall with large microvilli / stereocilia \ Highly specialised secretions Tight junctions between: Blood testis barrier Immunoprotective site Basal cells (BC): support cells (not stem cells) ↳ help with secretions that drive cells the principal Single, highly coiled tube o Transport: several layers of smooth muscle ↳ more & more muscular through the ejaculatory tract Sperm maturation – androgen dependent 0 Motility Metabolic changes Cell membrane changes Decapacitation (not fertile)  Vas deferens ☆ unusual to have ↳ can be used a inner longitudinal for identifying a SM section layer as vas deferens Sperm storage and transport Passes through inguinal canal - Superior and medial to ureters, posterior to bladder End at ejaculatory duct ~35cm long, thick smooth muscle tube 3 layers: 2 longitudinal with 1 circular in between Peristaltic contraction during ejaculation Doesn’t go all the way from testis to external! Stellate lumen, made by folded mucosa Muscle layers become thin near the ampulla ☐ Palpable, site of vasectomy Not immediately effective General anaesthetic not required 30 ejaculates or 2 months to eliminate residual sperm Seminal vesicles (~65% seminal volume) Paired coiled ducts 5-6cm long Tall mucosal folds with columnar cells stains pink Alkaline colloid: Vagina is acid Prostaglandins: ‘irritant’ → to get the vagina , uterus , cervix to contract Clotting proteins: form a coagulum Fructose Prostate (~30% seminal volume) ☆ thicker mucosal folds than SV Fibrous capsule holding many glandular structures Tall columnar cells with round and pale nuclei SV SV Liquefying enzyme: breakdown coagulum Distinct zones Anterior fibromuscular Central: 25% glandular mass Inner periurethral (transitional) Outer periurethral (submucosal glands) Peripheral 75% (main prostatic glands) from urethral crest Ejaculatory ducts join urethra in the prostate Corpora amylacea: Condensations of glycoproteins Bulbourethral glands Pre-ejaculatory fluid: An alkaline lubricant