The finger-like structures of the fallopian tube that catch the ovum are the

Etiology

The uterine tubes (oviducts, fallopian tubes) constitute a critical anatomic link between the ovary and uterus. Congenital or acquired abnormalities of the uterine tubes directly interfere with effective transport of ova or spermatozoa, depending on the anatomic region involved. The uterine tube is divided into an infundibulum, which possesses fimbria that aid collection of oocytes; an ampulla, which is long and thin walled; and an isthmus, which is thick, tortuous, and terminates at the uterotubal junction. Uterine tubes are lined with mucosa, have active cilia that tend to move material toward the uterus, have secretory activity, and are regulated by hormonal influences on muscle and blood supply.

Uterine tube disease occurs much more commonly than one would suspect and likely explains many cases of infertility characterized by repeat services without other overt signs or palpable abnormalities of the reproductive tract. Palpation detects some obvious uterine tube adhesions and enlargements but is a poor means of detection for subtle yet significant tubal adhesion, injury, or inflammation. Studies of slaughtered cattle suggest that 10% or more of cattle may have pathology in one or both uterine tubes.

Uterine tube congenital anomalies do exist but are less common than acquired pathology. Infections of the reproductive tract during the postpartum period, persistent endometritis, perimetritis, and other infections may involve the uterine tubes (salpingitis). Similarly, less spectacular but damaging salpingitis may be associated with Tritrichomonas foetus, Campylobacter fetus var venerealis, Ureaplasma diversum, Mycoplasma sp. and other organisms that infect the caudal reproductive tract and are discussed elsewhere in this chapter.

Traumatic injuries to the uterine tubes may accompany severe dystocia and were more common when manual removal of corpus luteum was practiced to instigate cycling in dairy cattle. Manual rupture of ovarian cysts also presents risk of trauma to the uterine tubes.

Anatomy of the Oviduct

Topography and Morphological Characteristics

The uterine tube (salpinx, oviduct, fallopian tube in humans) is a tubular, narrow, and sinuous structure with a length that can vary between species (approximately 10 cm in human species, 20 cm in sheep and horses, and about 25–30 cm in pigs).

It is located between the ovary and the uterus and is attached to the pelvic walls by a part of the broad ligament called mesosalpinx, which together with the oviduct itself and the proper ovarian ligament configures the ovarian bursa in most mammals, which surrounds the ovary (Fig. 1).

Fig. 1. Dorsal view of uterus and ovaries from adult cow. Detail of the right ovary covered by the infundibulum. 1: Broad ligament, 2: Oviduct, 3: Mesosalpinx, 4: Proper ovarian ligament, 5: Ampulla, 6: Isthmus.

In its course five main parts are differentiated (Fig. 2). The first one, called infundibulum (i), is the closest to the ovary. It has a funnel shape, thin walls and irregular conspicuous folds, called tubular fimbriae, which converge toward the abdominal orifice of the tube. The infundibulum continues with a tubular portion composed of two main segments, ampulla and isthmus. The ampulla (ii) runs laterally to the ovary describing a sinuous trajectory that ends in a narrow ampullary–isthmic junction (iii) connecting with the isthmus. The isthmus (iv) is the caudal part of the uterine tube which communicates with the uterus through a uterine orifice in the so-called uterotubal junction (v). The three-dimensional architecture of this junction acts as a barrier or sphincter between the uterine cavity and the isthmus. While smooth and progressive in ruminants and pigs, it is abrupt in horses and carnivores so that the uterine tube protrudes within the uterine lumen with a small uterine papilla. In the particular case of the human species the isthmus presents a transitional portion to join the uterus (uterine portion) which is a barrier not so functionally evident, as it will be seen later.

Fig. 2. Dorsal view of left horn and left ovary from a pig. (A) Infundibulum, (B) Ampulla, (C) ampullary–isthmic junction, (D) Isthmus, (E) Uterotubal junction, (F) Uterine horn, (G) Ovary, 1: Ovarian artery, 2: Uterine artery, 3: Tubal branch from the uterine artery, 4: Tubal branch from the ovarian artery, 5: arterial network in the mesosalpinx.

The inner morphology of the oviductal lumen is characterized by the presence of folds that are especially wide in the infundibulum and in the ampulla (Fig. 3). The largest ones or primary folds are arranged longitudinally along the whole length of the uterine tube. There are also smaller secondary folds with perpendicular disposition to the primary ones. Among the folds, there are deep grooves with sinuous pathways, and both structures together (folds and grooves) determine an irregular and highly complex lumen trajectory on the mucosa or endosalpinx (Fig. 3A). On the other hand, the number of folds is considerably reduced in the ampullary–isthmic junction, remaining only a few longitudinal folds in the isthmus, smaller and simpler than in the ampulla (Fig. 3B). In the ampulla and uterotubal junction, excavations are described in blind pouches and crypts, as well as elevations like polyps. These differences between the ampulla and the isthmus are related to functional aspects, as it will be seen later.

Fig. 3. Histological section of the mare oviduct stained with trichromic of Masson and viewed using light microscopy. (A) ampulla. The mucosa layer (Mu) presents numerous and big folds. Blood (arrows) and lymphatic vessels (arrowheads) are observed in the serosa layer (S). (B) isthmus. The mucosa layer (Mu) presents a important reduction of the number and size of the folds. The muscular layer (ML) is more developed in this region compared with the ampulla. Collagen fibers of the connective tissue present a green staining.

The reproductive status of the females as well as the phase of the reproductive cycle seem to influence the morphometric characteristics of the uterine tube. Thus, the length and its sinuous pathway increase in sexually adult females compared to prepubertal females, as well as among nulliparous and multiparous females. Similarly, the area of the oviductal lumen seems to be affected by these reproductive conditions. However, morphological aspects of the uterine tube, such as the length ratio between the ampulla and the isthmus, have been defined since puberty and are not affected by reproductive status or number of deliveries.

Clinical aspects.

The uterine tube is the one portion of the reproductive tract of mares where functional abnormalities or pathologic changes and their significance are less likely to be appreciated. The myoelectrical activity of the myosalpinx can be influenced by oxytocin and prostaglandin F2α (PGF). The clinical relevance of these modifications in oviductal function is yet to be determined. The presence of debris in the uterine tube has been described and is hypothesized to have an effect on tubal patency. Several techniques have been developed for the assessment of oviductal patency, but controversy exists over the prevalence of nonpatent oviducts and whether the observed debris actually represents a pathologic change.4,22 Hydrosalpinx is rare in mares, but cases have been reported.3,4,16,21 Mild to moderate inflammation and adhesions of the uterine tube have been noted in postmortem examinations of the horse; yet, as with other conditions observed in the uterine tubes, it is not known which oviductal changes have a negative effect on fertility and which represent normal variations. Several types of parovarian cystic structures occur in the vicinity of the oviducts. Some of these cysts are of mesonephric origin (epoöphoron and paroöphoron cysts). Although generally small and clinically significant, some of these structures, especially epoöphoron cysts, can become fairly large in the mare.4,13,16,21 Despite being listed as mesonephric in origin by some references, hydatids of Morgagni are, based on histologic evidence, paramesonephric in origin and represent accessory uterine tubes, which can become quite large and impede proper function of the reproductive tract.4,16,21

B Oviducts

The oviducts are paired, thin, transparent or white tubes that leave the ovary at its ventral surface (Herrick, 1909). They pass laterally and ventrally within the céphalothorax and join the gonopores at the base of the third walking legs. The distal portion of the oviduct is clear in immature females, but retains a yellow color in females that have spawned (Aiken and Waddy, 1980). Histological studies have shown the oviducts to comprise an outer layer of epithelium, connective tissue, muscle, basal lamina, and tall columnar epithelial cells (Herrick, 1909). The oviducal muscle is nonstriated in Homarus americanus, and is structurally similar to the microtubule-containing muscle surrounding the ovary (P. Talbot, unpublished data). [In contrast, the oviducal muscle of the palinurid lobster Jasus lalandii appears striated (Silberbauer, 1971).] The epithelium lining the oviducts is secretory and undergoes cyclic changes associated with development of the ovary and spawning (Herrick, 1909). Oviducal secretions are released prior to spawning and oocytes presumably pass through these secretions during spawning (Herrick, 1909); however, the effect of the secretions on oocytes is not known. The composition of oviducal secretions has not been examined in H. americanus, but may be similar to that of the crayfish, in which the secretory product is histochemically positive for acid and neutral mucopolysaccharides (Cheung, 1966).

Uterine tubes (Fig. 6.2-3)

The paired uterine tubes (left and right) are known as oviducts or “fallopian tubes” in humans. These narrow tubes transport the ova from the ovary to the uterine horn, following ovulation.

Proximally, the uterine tube widens into a funnel-shaped infundibulum, which is fimbriated (fringed). The ostium, or proximal opening of the infundibulum, occupies the ventral opening in the ovarian bursa, so during ovulation, the infundibulum “catches” the ovum somewhat like a baseball mitt and guides it across the narrow gap between ovary and uterine tube.

After successful mating, fertilization of each ovum occurs in the uterine tube. The zygotes (fertilized ova), and subsequently the early embryos, are then transported through the uterotubal junction into the uterine horn for implantation. The uterine tube remains in close association with the ovary for almost its entire length. It partially wraps around the ovary, beginning on the ventral aspect, then coursing cranially along the medial margin of the ovary to the cranial pole before doubling back along the dorsal aspect of the ovary on its way to meet the uterine horn just caudal to the caudal pole of the ovary. In the process, its portion of the broad ligament, the mesosalpinx, contributes to the wall of the ovarian bursa. The arterial and nerve supply and the venous and lymphatic drainage for the uterine tube run in the mesosalpinx, and are essentially as described for the ovary.

What is the finger like structure in fallopian tube called?

Which part of the fallopian tube captures the ovum?

Which term describes the finger like structures of the fallopian tube that catch the ovum as it is released by the ovary?

What is the name of the finger like branches of the fallopian tube that reach out into the pelvic cavity and pick up the released egg?