Oviductal Environment and Components of Fluid

Question 1

How long does a fertilized egg remain in the oviduct?

Answer 1

A few days.

Question 2

The fertilized embryo passes through the _____ of the oviduct and into the uterus.

Answer 2

Isthmus.

Question 3

What three characteristics of the oviduct facilitate embryo transport into the uterus?

Answer 3

1. Endocrine setting
2. Special structure
3. Musculature nature

Question 4

What provides the main nutritional support for embryo development prior to implantation?

Answer 4

Oviductal fluid components.

Question 5

Oviductal fluid plays what four main roles?

Answer 5

1. Sperm transport.
2. Oocyte fertilization.
3. Preimplantation embryo nutrition.
4. Preimplantation embryo transport to uterus.

Question 6

Where in the oviduct does fertilization occur?

Answer 6

Upper 1/3rd

Question 7

What is the embryonic origin of the oviductal portion of the female reproductive tract?

Answer 7

Anterior end of the Mullein ducts gave rise to the oviducts.

Question 8

What is the oviduct called in humans?

Answer 8

Fallopian tubes.

Question 9

How long is the pre-implantation embryo period for humans?

Answer 9

~3-5 days

Question 10

How does the oviduct transport an embryo to the uterus?

Answer 10

1. Beating cilia.

2. Muscular contractions.

Question 11

What five parts can the oviduct be divided into, begining from the end closest to the ovary (three parts plus two junctions)?

Answer 11

1. Infundibulum
2. Ampulla
3. Ampullary-isthmic junction
4. Isthmus
5. Utero-tubal junction

Question 12

Describe the structure and role of the infundibulum.

Answer 12

1. It is funnel-shaped and lies at the end of the oviduct.
2. The edges have fimbria to catch the ovulating oocyte.
3. More specifically, the ciliated surface of the fimbria “catch” the oocyte and move it along into the ampulla.

Question 13

Describe the structure and function of the ampulla.

Answer 13

1. Takes up about 1/2 space of the oviduct.
2. It is very mucus-y and has thin muscularis.
3. It is larger in diameter than the isthmus and is soft.
4. The area where it joins the isthmus is the ampullary-isthmus junction.

Question 14

Describe the structure and function of the ampullary-isthmic junction.

Answer 14

1. About halfway between the ovary and the uterus.
2. Approximately the site of fertilization.
3. Note: Cilia in the ampulla sweeps towards the ampullary-isthmic junction, which is the opposite direction of sperm transport…therefore it is suggested that cilia here does NOT help fertilization. (?)

Question 15

Describe the structure and function of the isthmus.

Answer 15

1. Found between the ampulla and uterotubal junction.
2. It’s about 1/2 length of the oviduct.
3. Muscularis are well developed and isthmus feels hard.
4. Note: Some evidence shows that cilia in isthmus beats towards ovaries.

Question 16

What are the three layers of the oviduct (shown in a cross-section)?

Answer 16

1. Mucosa
2. Muscularis
3. Serosa

Question 17

Describe the mucosa layer of the oviduct.

Answer 17

1. Lined by ciliated simple columnar epithelium as well as non-ciliated secretory cells.
2. Longitudinal folds have a delicate vascular lamina propria (which is loose connective tissue that supports mucosal epithelium movement).

Question 18

Describe the muscularis layer of the oviduct.

Answer 18

1. Has broad inner circular muscle that is poorly differentiated from narrow longitudinal muscle layer.
2. Note: this layer is NOT responsible for peristaltic movement of oocyte down the tube.

Question 19

Describe the serosa layer of the oviduct.

Answer 19

1. Outermost layer is epithelium and connective tissue.

Question 20

What are two functions of the foldings in the mucosa layer of the oviduct?

Answer 20

1. Increase surface area for nutrient delivery.

2. Cilia propels egg/zygote to uterus.

Question 21

What does “lumen” mean?

Answer 21

Hollow tube.

Question 22

What are the two main types of (epithelial) cells bordering the oviductal lumen?

Answer 22

1. Seg cells (non-ciliated or secretory).

2. Ciliated cells.

Question 23

Describe the cycle of hypertrophy and atrophy undergone by the secretory cells of the oviductal lumen during the female cycle.

Answer 23

1. Estrogen dominant part of cycle = increased secretory activity.
2. After progesterone administration/coitus, secretory granules are released (which forms oviduct fluid).
3. Oviductal fluid nourishes egg and aids transportation.
4. Cells also inhibit growth of microorganisms (protects egg).

Question 24

Describe the affect of hormonal changes on ciliated cells.

Answer 24

None - they do not provide content for oviductal fluid and they are not influenced by cyclic hormonal changes.

Question 25

What three primary components are found in oviductal fluid?

Answer 25

1. Electrolytes 2. Non-electrolytes 3. Macromolecules

Question 26

Describe the electrolytic components and their functions in oviductal fluid.

Answer 26

1. Contains: Na+, K+, Cl-, HCO3-, etc. 2. Responsible for: electrochemical gradient (Cl- moves from basil to apical poles of cells), maintaining pH and osmolarity, and driving force for movement of molecules like water and others into and out of the cell.

Question 27

Describe the non-electrolytic components (excluding macromolecules) and how they were derived, in oviductal fluid.

Answer 27

1. Contains: glucose, pyruvate, lactate, and amino acids. 2. Derived from blood into oviduct, synthesized in oviduct and secreted into lumen, or synthesized by cumulus cells in lumen like in the case of pyruvate.

Question 28

Describe the role of each non-electrolytic component of oviductal fluid (excluding macromolecules).

Answer 28

1. Pyruvic acid fuels first cleavage division of embryos. 2. Lactate acts synergistically with pyruvate from 2-cell stage. 3. Glucose comes into play after 8-cell stage. 4. Amino acids required for development of 1-cell into blastocyst in culture (usually albumin is good enough).

Question 29

Describe the origins and role of each main macromolecule in oviductal fluid.

Answer 29

1. Albumin (derived from blood) breaks down and supplies ample amino acids needed for embryo nourishment. 2. Immunoglobulin G (also derived from blood) with IgA in the cells act locally against microorganisms. 3. Glycoproteins (made in the oviduct) are possibly needed to make mucin coat around embryo, based on rabbit studies.

Question 30

What are the origins of the uterus?

Answer 30

Fusion of the paired Mullerian ducts of the fetus.

Question 31

What determines the type of uterus present in an adult?

Answer 31

The degree of fusion of the Mullerian duct during fetal development.

Question 32

What are three types of uteri and what kinds of animals are they typically present in?

Answer 32

1. Duplex (little fusion of Mullerian ducts causes two separate horns and TWO cervical openings) - opossums, rabbits, rodents. 2. Simplex (the other extreme - TOTAL fusion of Mullerian ducts with no uterine horns) - primates. 3. Bicornuate (an in-between from the uteri types mentioned above) - farm animals.

Question 33

What are the basic three layers (cross-section) of the uterus?

Answer 33

1. Endometrium 2. Myometrium 3. Perimetrium

Question 34

Describe the structure and function of the endometrial layer of the uterus.

Answer 34

1. Innermost layer with simple secretory tubular glands to conduce development of embryo. 2. Note: in cows/ewes the endometrium has caruncles sticking out which attach to cotyledons of embryo and allow mother-fetal exchange.

Question 35

How to the uterus endometrium tubular glands change during the female cycle?

Answer 35

1. Secretory phase: tubular glands become extremely convoluted and endometrium thickens. 2. Proliferative phase: tubular glands remain straight and simple.

Question 36

Describe the structure and function of the myometrium layer of the uterus.

Answer 36

1. Thick inner circular layer and thinner outer longitudinal layer. 2. Has noticeable muscular functioning in all aspects of reproduction from sperm transport to parturition (childbirth).