2.3: Functional Histology of the Uterine Tubes and Oocyte Journey into the Uterine Tube
- Page ID
- 91841
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)2.3.1 Uterine Tubes
The uterine tubes (also called fallopian tubes or oviducts) serve as the conduit of the oocyte from the ovary to the uterus. Each of the two uterine tubes is close but not directly connected to the ovary and divided into sections. The isthmus is the narrow medial end of each uterine tube connected to the uterus. The wide distal infundibulum flares out with slender, finger-like projections called fimbriae. The middle region of the tube, called the ampulla, is where fertilization often occurs.
The uterine tubes have three layers: an outer serosa, a middle smooth muscle layer, and an inner mucosal layer (Figure 2.3.10, A). In addition to its mucus-secreting cells, the inner mucosa contains ciliated cells that beat in the direction of the uterus, producing a current that will be critical to move the oocyte (Figure 2.3.10, B). Following ovulation, the secondary oocyte, surrounded by a few granulosa cells, is released into the peritoneal cavity. The nearby uterine tube, either left or right, receives the oocyte.
Figure 2.3.10 (A) A cross-section in the ampulla of the fallopian tube. The wall has a highly enfolded mucosa (columnar epithelium, black arrows; and lamina propria, blue arrows). Muscularis externa consists of inner circular (blue double-headed arrows) and outer longitudinal layers (green double-headed arrows) that intermingle. The fallopian tube is surrounded by a serosa (black double-headed arrows) and suspended by a mesosalpinx (red double-headed arrow) from the broad ligament. 400x. (B) Two folds of the fallopian tube mucosa of the ampulla are shown. The simple columnar epithelium lining the oviduct (black double-headed arrows) possesses both ciliated (black arrow) and secretory cells (green arrows), whose activity is regulated by ovarian hormones. Cilia (blue arrows), basal bodies (red arrows), and lumen (X). 1000x.
Image Source: Images used with permission from Digital Histology. Pakurar, Alice S. and John W. Bigbee. Carole W. Christman, Ph.D, Medical Illustrator. Digital Histology, (ND). This work is openly licensed via CC BY SA Creative Commons License. Available from Virginia Commonwealth University.
Unlike sperm, oocytes lack flagella and, therefore, cannot move on their own. So, how do they travel into the uterine tube and toward the uterus? High concentrations of estrogen that occur around the time of ovulation induce contractions of the smooth muscle along the length of the uterine tube. These contractions occur every 4 to 8 seconds, resulting in a coordinated movement that sweeps the surface of the ovary and the pelvic cavity. Current flowing toward the uterus is generated by coordinated beating of the cilia that line the outside and lumen of the length of the uterine tube. These cilia beat more strongly in response to the high estrogen concentrations that occur around the time of ovulation. As a result of these mechanisms, the oocyte–granulosa cell complex is pulled into the interior of the tube.
Once inside, the muscular contractions and beating cilia move the oocyte slowly toward the uterus. When fertilization does occur, sperm typically meets the egg while it is still moving through the ampulla. If the oocyte is successfully fertilized, the resulting zygote will begin to divide into two cells, then four, and so on, as it makes its way through the uterine tube and into the uterus. There, it will implant and continue to grow.
If the egg is not fertilized, it will simply degrade—either in the uterine tube or in the uterus, where it may be shed with the next menstrual period.
Glossary Terms
- Ampulla
- (of the uterine tube) Middle portion of the uterine tube in which fertilization often occurs
- Cilia
- Small appendage on certain cells formed by microtubules and modified for movement of materials across the cellular surface
- Fimbriae
- Fingerlike projections on the distal uterine tubes
- Flagellum
- Appendage on certain cells formed by microtubules and modified for movement
- Infundibulum
- (of the uterine tube) Wide, distal portion of the uterine tube terminating in fimbriae
- Isthmus
- Narrow, medial portion of the uterine tube that joins the uterus portion of the uterine tube terminating infimbriae
- Lumen
- Interior of a tubular structure such as a blood vessel or a portion of the alimentary canal through which blood, chyme, or other substances travel luteinization meiosis
- Oocyte
- Cell that results from the division of the oogonium and undergoes meiosis I at the LH surge and meiosis II at fertilization to become a haploid ovum
- Ovary
- Female gonad that produces oocytes and sex steroid hormones (notably estrogen and progesterone)
- Peritoneal cavity
- Space enclosed by the peritoneum. It is divided into two portions, the greater sac and the lesser sac or omental bursa, which lies behind the STOMACH. The two sacs are connected by the foramen of Winslow, or epiploic foramen
- Uterine tubes
- (also, fallopian tubes or oviducts) Ducts that facilitate transport of an ovulated oocyte to the uterus
- Uterus
- Muscular hollow organ in which a fertilized egg develops into a fetus
- Zygote
- Fertilized OVUM resulting from the fusion of a male and a female gamete
Image Acknolwedgements
Pakurar, Alice S. and John W. Bigbee. Carole W. Christman, Ph.D, Medical Illustrator. Digital Histology, (ND). This work is openly licensed via CC BY SA Creative Commons License. Available from Virginia Commonwealth University.