Journey of the gametes

1. Identify the head (caput), body (corpus) and tail (cauda) segments of epididymis according to their cellular structural variations. 2. Relate the histology of the accessory glands and spermatic cord to their functions. 3. Identify the histological features of the uterine tube, uterus and cervix and describe how they change during the oestrous cycle.

epididymis head structure and how it relates to function

• lumen

• epithelium type

• head end: tubules have relatively small lumen and thick wall. have visible stereocilia (seen as pink strands in histology) and has pesudostratified epithelium with very crowded nuclei in its tall cells

  • so head resorbs fluid bathing the sperm

  • fluid originate from sertoli cells and moved sperm by bulk flow

  • but sperm has to be concentrated by the removal of liquid

  • stereocilia increase surface area for resorption

tail area of the epididymis

• lumen

• epithelium

• function

• muscle and why

• larger lumen

• thinner epithelium

• sperm are being stored here so there is less need for resorption

• so less stereocilia

• smooth muscle around the epithelium is thicker than in the head reflecting the need to actively move the sperm to the ductus deferens

what are the structures around the ductus deferens

• large number of blood vessels

  • pampiniform plexus

  • testicular blood supply and a heat exchanger

• skeletal muscle

  • external cremaster muscle

  • raise or lower the testes bringing them closer or further from the body and providing further temperature regulation

what are the 2 accessory glands and what do they do

• what type of glands are they

• what type of epithelium do they have

• seminal and prostate

• produce the majority of seminal fluid which carry, norish and supprt the sperm during and after ejaculatio

• both are compound alveolar tubular glands

• both have pseudostratified columnar or cuboidal epithelia

• in seminal vesicles the epithelium is classed as pseudostratified as a result of very rare basal cells which lie out of line with all the other epithelial nuclei

fornix

arch shaped structures resulting from part of the cervx extending into the vagina

why is artificial insemination in a ewe difficult

• highy folded surface of the cervical lumen

• create branch points where the central canal turns and a canula can be misdirected into a large fold

mucus in anoestrus vs oestrus

• in anoestrus the mucus is produced in low volumes but is thick restricting movement of sperm or pathogens

• in oestrs it is thinner but produced in larger volumes

how are pathogens removed whilst protecting sperm

fluid flows faster in the main lumen and slower in grooves

how does the ampulla and isthmus structure relate to function

• ampulla has larger lumen and less muscle

• isthmus can restrict dimensions to prevent egg from entering

• sperm can pass through to the egg at the ampullary isthmic junction for fertilisation but may also be protected by constrained environment of the isthmus is they arrive before the egg

• under hormonal control the muscle of the isthmus relaxes when the uters is ready to recieve the fertilised egg

what is the function of the endometrial glands in anoestrus, oestrus and pregnancy and strutural changes

• contribution to cervical mucus before pregnancy and will support embryo afterwards

• in anoestrus they are relatively sparse becoming more prominent as straight glands in oestrus

  • driven by the increase in oestrogen levels

  • proliferative phase

• within pregnancy they expand much further becoming coiled to accomodate the amount of secretory epithelium required

  • driven by progesterone

  • secretory phase

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